VFUG Newsletters

May, 2001

Ed. Spoke -- By Carl Warner

An Enhanced Collection Class, Part 1 -- J. M. Edgar

Where's the Marketing? -- Michael Asherman

Software Development Agreements -- J. M. Edgar, JD

Resources-- By Ed.
       o Visual FoxPro
       o MS KnowledgeBase
       o Various MS Links
       o .NET
       o XML
       o General Interest

Tips 'n Tricks -- By the Membership
       o GenLoader - A WSH Loader Wizard -- John Koziol/George Tasker
       o Benchmarking: Visual FoxPro 6.0 vs. Inprise Delphi 5 -- Ionut D. Baldazar
       o Visual Class Navigators Library -- Alexander Khudyakov
       o How can I color code records/cells in a grid? -- Chris R. Chamberlain
       o Set Your Exe's Start Path On The Fly -- Ariel Gimenez
       o VFPLife.zip -- A VFP6 Mathematical Game -- John Koziol
       o Copying Files? -- Animated GIF Humor
       o Joke of the Month

ON SHUTDOWN....

Ed. Spoke

By Carl Warner

Yes, we are done accepting articles and tips for this issue of the newsletter.  Next month's will be coming along before we all realize it.  So, please contribute now for the June issue which will begin posting online on May 6th.

Within a week from now, we will have reached the 30,000 member plateau at VFUG.  That is positively awesome!  When I started being editor of this newsletter in October of 1997, we had just reached the 7,000 member count.  That's a lot of Fox developers and afficionados signing up.  We should all be very happy that we are definitely not alone in our interest of FoxPro, whatever version.

VFUG Support for Visual FoxPro -- Besides this monthly newsletter that is available online as it is being created, we have a few avenues offered up to every VFUG member, if they would just choose to use them.  We have an online threaded message forum that has gotten more use as of late, we have a list server that gets very little use by the membership, and we have a weekly online chat every Thursday that is only attended by a handful of the VFUG membership.  These are all ways to get questions answered, to lurk and learn something, or to show everyone how smart you are by answering the questions the rest of us can't explain to another member.  Most of you choose not to avail yourselves of these resources and, not only are you missing out, but so is the whole VFUG and Fox community by so many members not sharing information.  If you want to get all of your information from the software vendors, good luck in your developer career.

While many members think that sending me a message that says "unsubscribe" will get you removed from the mailing list, it will not.  Why not?  Because this newsletter is not on a list server, and it's availability is administered by you in your personal account information.  Select Members...Update Your Account Information (hiding on the bottom of the page), Mailing Option (toward the bottom of the page).  Then, don't forget to click on the button at the very bottom of that page to Save your account updates.

Now, on to the VFUG List Server which you can actually "unsubscribe" from if you just would "subscribe" to it to begin with.   This list broadcasts e-mail questions and answers into your mailbox without the use of a browser or having to consciously (or unconsciously) visit the VFUG website.   Many of you who have been on other list servers know how easy it is to sit back and receive e-mail all day without having to Browse for the same kind of Q&A somewhere on the 'net.  Plus, you generally setup a Rule in your E-mail reader to shift all incoming mail from any List Server to a specific e-mail folder so you can read the messages at your leisure.  How do you get subscribed? 

From the e-mail address you want to get VFUG Fox-related e-mails:

Setup to send a text e-mail message (no HTML or RTF)

address the e-mail TO:  ListServer@VFUG.Org

Subject doesn't matter, but you could type "subscribe" there.

in the BODY of the message: subscribe VFUGList <put your name here>

Example: subscribe VFUGList Dave Fulton

Then, send that message!

[You will get a confirmation whether it succeeded or not.]

Easy, right?   If you haven't done it yet, do it today.

As far as the VFUG Forum that is online at the site and accessible via a browser, visit there often to post questions, comments, or try to answers the questions of others.  But, I have to make some comments about that area right now.  Everybody involved in VFUG, whether it's you the membership or the officers, are not paid in any way.  All of this is a volunteer effort and any advice or help you get is purely out of the goodness of someone's heart.  So, what do we ask in return?  Do not demand help or criticize someone's effort to help you in any way.  Be polite and civil.  You are the one asking for free help.  If you get an answer that isn't exactly what you're looking for, ask again differently but don't be critical of the advice you just got.  If you get advice that seems to require that you spend a little money, it probably is because the solution you need will involve far more time and effort than anyone could possibly give you in the scope of a message or two in any online message.   We all don't have the time to do each other's programming work.  If you don't follow those simple guidelines, you probably will get your feelings hurt.  Treat others as you'd like to be treated and don't abuse your privileges for free advice.

Let's move on to other things.

It looks as though VFP7 will ship on or about June 6th, 2001.  That is according to what Amazon.com has posted for a ship date at their site.  You can pre-order the upgrade or the full package right now.  See below under Resources...Visual FoxPro for those URL links.

That leads us to the contents of this newsletter issue.  Since VFP has split off from Visual Studio and is its own little entity within Microsoft, most Fox developers are rightfully concerned about what will be done differently now with the product to help it to gain respect and sales in the general developer world.  Many of us know that the effort on the part of MS as a whole in bringing attention to VFP has not been where we'd like to see it.  What can you do as a developer to help send a message to MS about how you feel?  See the article in this newsletter entitled "Where's the Marketing?".  Read it and respond as you wish.  The article directs you on where to go on the 'net to get your voice heard within the collective Fox developer community.

Jim Edgar has two great and very different articles in this month's issue.  He graciously added a second article when he could tell that we were a little short on material.  Well, we're not even close to short now.  He first submitted an article on legal aspects of software agreements.  This is very good reading especially for all independent contractors doing software development.  The second article is the first in a two-part technical series on an enhanced collection class.  Check it out.

Also, in the Tips 'n Tricks section there are some great tips and downloadable files.  The downloadable files, as usual, are also posted in the VFUG File Archive.

Don't forget to check out the Joke of the Month that won't be available in the e-mailed text version.

And, lastly, there are more than enough internet resources for you to look through to find at least one or two that interest you that you weren't aware of.

The Hentzenwerke Publishing book on getting VFP certified shipped within the last week.  I just got a copy of the book on Friday and don't have the time to get a decent book review together for this issue.  But, I'll post a review on that book for the June issue and it will be available online, before the June e-mailing, as soon as I get it reviewed.  From my quick look at the book, it looks good.  But, it's way too early to comment in detail.

Keep hanging in there...

-- Ed.

   Back To Top

VFUG Officers:

An Enhanced Collection Class, Part 1

J. M. Edgar

A Collection is an ordered set of items that can be referred to and manipulated as a unit.  The items or members of a collection need only be related by the fact that they are in the collection.  Members in a collection do not have to share the same data type.  A collection is similar to an array, but unlike an array has built-in methods to manipulate its members.

Visual FoxPro™ uses collections built into its foundation classes.  The _SCREEN has a Forms collection, a Form owns two collections: the Controls collection and the Objects collection.  The Pageframe has a Pages collection.  We can read the content of these collections, but cannot otherwise manipulate them.  Their usefulness is therefore very limited.

This article addresses the requirements for and creation of our own reusable collection class.  Next month, our collection class will used to solve some interesting ( at least I think they’re interesting) programming problems.

Collection Properties and Methods.

A collection class of some kind is available in almost development languages and has a well-understood set of properties and methods.

Items:            The collection itself is just a framework that holds content.  Content is arranged as discrete items (terminology varies considerably, so an “item” in one collection is a “member” or “element” of another even among Microsoft products).

An Item is nothing more than an addressable location within the collection where content is stored.  Items may be implemented as objects or properties of the collection.  The advantage of creating an Item as an object is that we can hang many neat properties on the object making it both powerful and flexible.  Most graphics collections, for example, define object items that contain information defining how a particular point is to be drawn.  The disadvantage of object items is that it is complicated to create an indexing object.   It is simpler to implement the item as an indexed property.  In FoxPro™ we already have a native indexed property, the array, so if we create our items as an indexed property, we can used the native array to greatly simplify our implementation.

Just as in an array, an integer index is used to point to the place in the collection where a particular content is stored.  Items are addressed as:  oCollection.Item[ n ], where n is an integer. 

An index may be zero-based or one-based.  In a zero-based collection, the first item in the collection is addressed as oCollection.Item[ 0 ] and the last item as oCollection.Item[ oCollection.Count – 1 ].  These indices are popular in development languages because they greatly simplify array mathematics. 

The FoxPro™ standard is the one-based index inherited from dBaseII.  The first item in the collection is addressed as oCollection.Item[ 1 ] and the last item as oCollection.Item[ oCollection.Count ].  A one-based index makes it easier to use a FoxPro™ array to store the items in an array without a lot of complex index management.

Items in a collection are addressed with the following syntax:  oCollection.Item[ n ].  In many collections, the “Item” portion of the syntax is a default property.  A default property is one that is assumed when omitted, so that the abbreviated syntax oCollection[ n ] is the equivalent of oCollection.Item[ n ].   In FoxPro™, however, we will have to use the full syntax since the language makes no provision for default properties.

In some collection classes, items in a collection cannot be addressed directly, but must be addressed through a method.  For example, in Visual Basic, oCollection.Item( n ) is used to return the content of Item[ n ].  In our collection, we will give the user a choice of using the method oCollection.Value( n ) to return the content of Item[ n ] or to address the item such as uContent = oCollection.Item[ n ].

An Item in a collection usually contains just one data position.  But, it could contain many positions, each position holding content.  We would then have to use a second index to address the item such as oCollection.Item[ n₁, n₂ ] where n₁ points to the Item and n₂ points to a discrete position within the Item.  Single- and multiple-position items can be mixed in a collection.

Typically, any kind of data can be stored in a collection, and the data types may be mixed.  Indeed, an item may even contain a reference to another collection object, making multi-dimensional “collections” possible.

Count:           The Count (or Length) property specifies the number of items in the collection.  To ensure that our Count is always accurate, we will create and raise a Count_Access() event each time Count is read to recalculate the number of items.

Add():            The Add() method inserts an Item into the collection.  It typically has the following minimum syntax:

myCollection.Add( uContent [, nIndex ] ),

where uContent is the data to be stored in the item pointed to by nIndex.  If nIndex is omitted, the item is appended to the end of the collection.   There are many variations to the Add() method.  For example in Visual Basic the Add() method accepts parameters that indicate whether new item is to be inserted before or after an existing item in the collection.

 In our implementation,  we are going to make the Add() method also handle updates.  A collection class does not normally support an update process.  Items are “updated” by being removed, modified, then added back to the collection.  A collection class is much more useful, however, it its content can be updated.

Remove().     The Remove() method deletes an item from the collection.  For example,

myCollecton.Remove( [ nIndex ] )

removes the item at position nIndex.  If nIndex is omitted, the last item in the collection is removed.  In the standard collection, nIndex would always be a pointer to a location.  In our collection class, we are going to permit the user to also pass content as an argument to Remove() such as:

myCollection.Remove( uContent ).

where uContent specifies the content to be removed from the collection.  Remove() then locates the content in the collection and removes the item having that content.

Non-Standard Properties and Methods

The standard set of collection properties are very basic.  To make the collection more useful and flexible, a number of enhancements immediately suggest themselves.

It would be handy to be able to determine the item number at which a certain content is located, to be able to return the content at a location specified by an index and to completely remove all items in a collection with a simple process.   In our collection, these processes are implemented as follows:

Value( nIndex )        Returns the content of the item at nIndex.  This is similar to the Visual Basic Item() method.

Index( uContent )    Returns the index of the item containing uContent.

Clear()                       Empties the collection, and nulls any object references that were part of the collection.

Our only non-standard property is NewItemIndex.   It specifies as an integer the item index of the last item added to the collection.  This property is set in the Add() method.

So without further fuss, let’s code.

Creating a Collection Class

We will base our collection on the VFP custom class.  The custom class is a non-visible class that has few native properties or methods and therefore has a very small footprint and little object overhead.

Create a new custom class named “Collection” in the class library of your choice.

Add the Count property to the class and set it to zero.  This is the only property that must exist when the class is instantiated.  Otherwise, the Count_Access() event we are going to write below will sometimes not work properly (early- and late-binding issues).

We are going to add all other properties through code in the Init() event.  There is no reason these “internal” properties cannot be added to the property sheet.  It is generally good practice to try to minimize the number of properties appearing in the property sheet by including only those that may need to be set.  If the property is intended solely for internally use or does not need to be set in the property sheet, there is no reason to expose it in the property sheet for someone to fool with.

Modified Methods:

Init():            Add the following to the Init() event code of your collection class.  All this does is add two internal properties to the class.  Again, you may elect to add these to your class through your project manager.

*     Collection.Init()
*
*     Add internal properties to the class
*

WITH this
*     The array that holds the collection members.  This array is always initialized with
*     .NULL. that signifies to the Count_Access() event that the collection has no members.
      .AddProperty( "Item[1]", .NULL. )
*     Specifies the index of a new member added to the collection.  The index is a pointer
*     to the location of the member in the collection.
      .AddProperty( "NewItemIndex", 0 )
ENDWITH

RETURN .T.

Destroy():    Include the following code in the Destroy() event.  Destroy() calls the Clear() method of the collection just in case the members of the collection contain object references.  Any object references in the collection should be set to .NULL. or .F. when the collection is destroyed to prevent hanging references from clobbering your form release.

*     Collection.Destroy()
*
*     If the members are composed of object references, the Clear() method sets the
*     references to .NULL. before collapsing the Item[] array.  This eliminates any
*     hanging object references which may prevent a form from closing.
this.Clear()
RETURN

New Methods:

Add():   The Add() method handles all additions and overwrites.

The usual collection supports adding and removing items.  Added items are placed at the end of the collection.  There is usually no way to insert an item in the middle of the collection.  Similarly, once content is added to the collection, there is no means of overwriting the content.  The usual, if inelegant, solution is to remove the old content and append a new item with the revised content.

To make our collection more useful, we want to be able to both update existing content and insert a new item at any place in the collection.

We also want our design to recognize that some processes are used more frequently than others.  These processes in order of frequency of use are:

·                    Appending a new item to the end of the collection,

·                    Updating an existing item in the collection,

·                    Inserting a new item in the middle of the collection.

Our method design should implement the most frequently used process with the simplest syntax, adding to the complexity of syntax as frequency of use decreases.  With this precept in mind, the design requires the least complex syntax to append an item at the end of the collection and the most complex syntax to insert an item in the middle of the collection.  The Add() syntax is,

 Add( uContent [, nIndex1 ] [, nIndex2 ] [,lInsert ] ),

where,

uContent        Specifies the content to be added.  This may be of any valid data type, but it cannot be NULL.  NULL is used to indicate an empty collection.  Any attempt to add .NULL. to the collection is ignored.  If uContent is omitted, nothing will be added to the collection.

            nIndex₁           Specifies the item to be added, inserted or replaced. 

If this parameter is omitted, zero or greater than Count, the new item will be appended at the end of the collection.  If its value is greater than Count + 1, the new item will nonetheless be appended at Count + 1.  Items must be added to the collection in sequence.  Skipping is not allowed.  Item 5 cannot be added before Item 4.  If there are two items in the collection, an attempt to add content at item 5 will actually cause it to be added as item 3.

If the nIndex₁ points to an item that already exists, it is presumed that the content of the item is to be replaced. unless lInsert is true.

To find out where a content was actually added, test NewItemIndex that holds the index of the last item added to the collection. 

nIndex₂            Specifies the position on the item were the content is to be added.  If the position does not yet exist, it will be created.  Positions on an item do not have to be filled in sequence.  Content can be added to position 3 before it is added to position 1 or 2. 

                                   If nIndex₂ is omitted or zero, the content will be added at the first (default) position on the item. 

lInsert              If true, forces the insertion of a new item.  If omitted or false, the content of an existing item will be replaced with the new content.  If the item specified in nIndex₁ does not exist, it will be added irrespective of the setting of lInsert, which is, in effect, ignored.

Here is the Add() code.  The comments explain what each section does.

*     Collection.Add()
*
*     OVERVIEW:   Add a new item to a collection object or replace an existing item with new *  *                  content.
*     PARAMETERS: tuContent   Specifies he content to be associated with the new item.
*                             May be any data type, but may not be .NULL.
*
*                 tnIndex1    Specifies position in the collection at which the new item is
*                             to be inserted or where existing content is to be replaced.
*                             If omitted, zero, or larger than the Count property setting,
*                             the item is added at the end of the collection.
*
*                 tnIndex2    Specifies the column in which the value is to be added.
*                             Required for multi-positional items.  Otherwise ignored.
*
*                 tlInsert    Specifies whether a new item is to be inserted into the
*                              collection.
*
*     RETURN:     (L)         True if the content was successfully added to the collection.
*

LPARAMETERS tuContent, tnIndex1, tnIndex2, tlInsert

LOCAL lnCount, lnNewCount, lnPosition, lnItems

WITH this 

*     Test and normalize parameters 

      IF PCOUNT() = 0 .OR. ISNULL( tuContent )
            *     The content to be added to the collection was not passed or passed as a
            *      .NULL. 
            *     Just exit.  Blank or .NULL. content cannot be added to the collection.
            RETURN .F.
      ENDIF     

*     Since reading Count triggers Count_Access() we do not want to read it over and
*     over.  Read it once and store the result in a local variable.
lnCount     = .Count   
lnNewCount  = lnCount + 1

IF    PCOUNT() = 1 ;
   .OR. VARTYPE( tnIndex1 ) # “N” ;
   .OR. tnIndex1 < 1 ;
   .OR. tnIndex1 > lnNewCount
*     If the item index was not passed, is the wrong data type, is less than 1
*     or greater than Count + 1; execute the default operation, i.e. the new item is
*     to be added at the end of the collection.
        tnIndex1 = lnNewCount
ENDIF
*     Items must be added to the collection in sequence without skipping over
*     an item. The item index parameter cannot, therefore, be greater than lnNewCount.
*     If the item index is greater than lnNewcount, reduce it to lnNewCount.
*     The user may test NewItemIndex to find out where an item was actually added.
tnIndex1 = MIN( tnIndex1, lnNewCount )

IF PCOUNT() < 3 .OR. VARTYPE( tnIndex2 ) # "N”
*     Position index not passed for a multi-position item.  If the item to be
*     added or updated is a multi-position item, assume the content is to be
*     placed at position 1 of the item.  If the item to be updated is a single
*     position item, the content can be added only to the single position and
*     tnIndex2 is irrelevant.  Set it to 0 (zero) so lnPositions will be correctly
*     calculated below.

IF ALEN( .Item, 2 ) > 0
      tnIndex2 = 1
ELSE
      tnIndex2 = 0
ENDIF

      ENDIF

      *     Get the number of positions to be added to the items in a multi-position
      *     collection.  This value is the greater of tnIndex2 or ALEN( .Item, 2 ). If the
      *     item to be added or updated is a single-position item, lnPositions will be zero.

lnPositions = MAX( tnIndex2, ALEN( .Item, 2 ) )

       *     Find out if the content is to be inserted into the collection or replace
       *     existing content. 

      IF ( PCOUNT() = 4 .AND. VARTYPE( tlInsert ) = "L" .AND. tlInsert ) ;
            .OR. tnIndex1 > ALEN( .Item, 1 )
             *     If four parameters were passed, the 4^th parameter is logical and true,  force
             *     an insert.
            tlInsert = .T.
            lnItems  = ALEN( .Item, 1 ) + 1
      ELSE
            tlInsert = .F.
            lnItems  = ALEN( .Item, 1 )
      ENDIF
       *     If the array does not already contain at least that number of columns specified
              *     in lnPositions, dimension the array to the number of columns specified in  
       *     lnPositions.
      IF lnPositions > 1 .AND. lnPositions > ALEN( .Item, 2 )
            DIMENSION .Item( tnIndex1, lnPositions )
      ENDIF
      IF tlInsert ;
                 .OR. ( tnIndex1 > ALEN( .Item, 1 ) ) ;
                 .OR. ( lnItems  > ALEN( .Item, 1 ) )
      *     If item[ 1 ] is .NULL., the collection is empty, so the new item
            *     will be Item[ 1 ], but if item[ 1 ] is not .NULL., then we must
            *     add an item.
               IF ISNULL( .Item[1] )
                                    *     The collection should have already been cleared if the Item[ 1 ]
                                    *     is .NULL.  But, in case it has not been, clear it now.
                  .Clear() 
            ELSE

*     We must add a blank row to the Item array before calling AINS(). 
*     AINS() does not re-dimension the array before inserting a new item. 
*     If the array is not re-dimensioned, the last item in the collection
*     will be lost when the new item is inserted.

                  IF ALEN( .Item, 2 ) > 0
                        DIMENSION .Item( tnIndex1, ALEN( .Item, 2 ) )
                  ELSE 
                        DIMENSION .Item( tnIndex1 )
                  ENDIF 

*     Insert an item into the array at tnIndex1.  The new item is
*     inserted just before tnIndex1.

                  AINS( .Item, tnIndex1 )           

            ENDIF

       ENDIF

      *     If this is a multi-positional item, tnIndex2 will not be empty.  Passing a non-
            *     empty tnIndex2 indicates that tuContent is to be added to the item at the
            *     position specified in tnIndex2.  Note that tnIndex2 = 0 is essentially the same
            *     as tnIndex2 = since in both cases the content will be inserted at position 1 on
            *     the item.

      IF !EMPTY( tnIndex2 )
            .Item[ tnIndex1, tnIndex2 ] = tuContent
      ELSE 
            .Item[ tnIndex1 ] = tuContent
      ENDIF

*     Save tnIndex1 as a property.  NewItemIndex is used to remember the location
*     of the last item added, inserted or updated.

      .NewItemIndex = tnIndex1

ENDWITH

RETURN .T.

Clear():      Clear() removes all items from the collection.  It takes no arguments.  In a “cleared” collection, the Count property specifies zero even though there is actually one (.NULL.) element in the Item[] array.   FoxPro™ does not allow an empty array   An array must contain at least one element.  Therefore, the Count_Access() method determines whether any items are in the collection by reference to the content of Collection.Item[ 1 ].  If it is .NULL. and ALEN( Collection.Item, 1 ] ) = 1, the collection is considered empty (Count = 0).

*     Collection.Clear()
*
*     Clears all of the items in the collection

WITH this
     *     As a precaution, nullify any object references that may be in the collection.
      DIMENSION .Item( 1 )
      .Item[ 1 ] = .NULL.     
ENDWITH 

RETURN 

Count_Access():  The Count_Access() event occurs when the setting of the Count property is read.  Count specifies the number of items in the collection.  Since the number of items is not always the number of elements in the Item[] array, some adjustment has to be made. 

A VFP array can never contain zero elements, but a collection may contain zero items.  Consequently, if the array contains one element, this event determines whether there are one or zero items in the collection.  Count is treated like a read-only property.  Its value cannot be set except in this method.  If it is set elsewhere, the setting is ignored. 

*     Collection.Count_Access()
*
*     Return the number of members in the collection.

WITH this
      *     If nothing has been added to the collection or all of its members have been
      *     removed, the value of .Item will be .NULL.

      IF !ISNULL( .Item[ 1 ] )
            .Count = ALEN( .Item, 1 )
            RETURN .Count
      ENDIF

ENDWITH 

RETURN 0 

Remove():   The Remove() method deletes a specified item from the collection.  An item is specified by passing either its index or its content.  It syntax is,

Remove( nIndex | uContent ), 

where nIndex specifies the item to be removed or uContent specifies the content of the item to be removed. 

If an index is passed, the item located at the position specified by the index is removed.  If content is passed, the item having that content is located and removed.  Content is not position-specific in two-dimensional arrays.  If the content is found in any position on an item, the item is removed.  If the content is contained in more than one item, the first item having the content is removed. 

If content is a number, it may look like an index.  The second parameter of the method sorts this out.  If the first parameter is numeric, it is assumed an index unless the second parameter is passed as true (.T.).   In such case, the number is treated as content and the collection is searched for the number. 

*     Collection.Remove()
*
*     OVERVIEW:   Used to remove an item from a collection.  The entire item is removed
*                  whether or not the item is a one- or two-positional item.
*
*     PARAMETERS: tuParm      The content of an value to be located in the collection OR an
*                              integer index specifying the item to be removed.
*
*                 tlSearch    Specifies whether a numeric tuParm represents the content of an
*                             member to be located in the collection or the index of an item to
*                             be removed.  If omitted or false, tuParm is presumed to be an
*                              index.
*                             If true, tuParm is content to be located in the collection. 
*                              tlSeach has no effect unless tuParm is numeric.
*    
*     RETURN:     (L)         True if the specified item is removed.
*

LPARAMETERS tuParm, tlSearch 

LOCAL ll2Dim, lnElement, lnItemIndex, lnElementCount, lnI

lnItemIndex = 0 

WITH this 

*     Get the number of elements in the array.  If we need to look for tuParm by
*     value, we will look at every element of the Item[] array then return a row
*     index using ASUBSCRIPT()

      lnElementCount = ALEN( .Item ) 

      *     Find out if this is a two-dimensional array.

      ll2Dim = ALEN( .Item, 2 ) > 0     

      DO CASE     

      CASE PCOUNT() = 0

            *     Index not passed.  Assume the item is to be removed from the
                        *     end of the collection

            lnItemIndex = ALEN( .Item, 1 )           

      CASE VARTYPE( tuParm ) = "O"

           *     If tuParm is an object reference to be located in the collection,
                      *     ASCAN() cannot be used because it will not accept an object as a
           *     search expression.

            FOR lnI = 1 TO lnElementCount           

                  IF ISNULL( .Item[ lnI ] ) .OR. .Item[ lnI ] = tuParm                 

                        IF ll2Dim

                              *     If this is a two-dimensional array, get the
                              *      “row” that lnI belongs in from ASUBSCRIPT()

                              lnItemIndex = ASUBSCRIPT( .Item, lnI, 1 )

                        ELSE

                              *     If this is a one-dimensional array, lnI
                              *      already points to the correct position.

                              lnItemIndex = lnI

                        ENDIF                                   

                        EXIT

                  ENDIF

            NEXT                                   

      CASE ( VARTYPE( tlSearch ) = "L" .AND. tlSearch ) ;
            .OR. VARTYPE( tuParm ) # "N"

            *     tuParm is a value to be looked up.  If tuParm is found in the collection,
                        *     its row location is calculated and returned. 

            lnElement = ASCAN( .Item, tuParm ) 

            lnItemIndex = ;
                        IIF( lnElement > 0 .AND. ll2Dim, ;
                        ASUBSCRIPT( .Item, lnElement, 1 ), ;
                        lnElement ;

                     )

      OTHERWISE
            *     tuParm is a numeric row index
            lnItemIndex = INT( tuParm )
      ENDCASE    

      IF lnItemIndex > 0 

*     A FoxPro array cannot contain fewer than one element.  Consequently if
*     the last element is removed, the element count will still be 1, but the
*     value of the array will be .F.  We can’t tell whether this .F. is due to
*     removing the last element or if it is an actual value.  Therefore, when
*     the last element is removed from an array, set it to .NULL.

IF ALEN( .Item, 1 ) = 1
          *     We don’t have to write code to do this since the Clear() method
     *     will set the array to .NULL. 
      .Clear()
ELSE

                  *     Remove item from the collection.

                  ADEL( .Item, lnItemIndex )           

                  *     Redimension the collection to remove the last row that is now empty.
                  *     But, since an array cannot be dimensioned to zero rows, make certain
                  *     it will remain dimensioned to at least one row.

            IF ll2Dim
                  DIMENSION .Item( MAX( ALEN( .Item, 1 ) - 1, 1 ), ALEN( .Item, 2 ) )
            ELSE
                  DIMENSION .Item( MAX( ALEN( .Item, 1 ) - 1, 1 ) )
            ENDIF
      ENDIF     

            *     Adjust lnElementCount in case lnElementCount - 1 = 0.  This a little
            *     obtuse, but stems from the fact that an array cannot have zero elements
            *     in FoxPro™.
            *     If Item[] had one row, and one is removed, it would have zero rows,
            *     which it cannot have.  Thus since its minimum rows is one, if this row
            *     is removed, its row count is still one (albeit an empty row), so
            *     adjust lnElementCount to 2 so the test below works where the number
            *     of rows in the array used to be 1.

            lnElementCount = MAX( lnElementCount, 2 )

      ENDIF     

      *     If the item was removed and the collection resized, the current length
      *     of the collection will be less than the former length

      RETURN ALEN( .Item, 1 ) < lnElementCount     

ENDWITH 

Index():  Index() returns the item index of the first item having the content specified in its argument.  Its syntax is, 

Index( uContent  [, lCaseSensitive ] ), 

where

 uContent specifies the content to be located and

lCaseSensitive specifies whether a string content is case sensitive.  By default, the search is case insensitive.  Only if lCaseSensitive is true will case be considered searching for character content.  If the specified content is not found in the collection, 0 (zero) is returned.

*     Collection.Index()
*
*     OVERVIEW:   Locates a value in the collection and returns an integer representing
*                 a pointer to the position in the collection where the value was found.
*
*     PARAMETERS: tuValue           The content to be found.
*
*                 tlCaseSensitive   Specifies whether strings are to be matched by case.
*                                   Default is false (matches will be case-insensitive).
*                                   Has no effect on non-string content.
*
*     RETURN:     (N)   The pointer to the item in which the value was located.
*                       If the value is not in the collection, returns 0 (zero).
*
*

LPARAMETERS tuValue, tlCaseSensitive

LOCAL lnI, lnElement

WITH this

      *     If there are no members in the collection, return 0 since tuValue cannot
      *     possibly be in an empty collection.

      IF .Count = 0
            RETURN 0
      ENDIF

      *     Initialize lnElement to zero

lnElement = 0

*     Look for tuValue in the collection.  This search pattern works for one- and multi-
*     positional items.

      FOR lnI = 1 TO ALEN( .Item )
            DO CASE
            *     Case insensitive search for a string
                              CASE !( tlCaseSensitive ) ;
                                   .AND. VARTYPE( .Item[ lnI ] ) = "C" ;
                                   .AND. VARTYPE( tuValue ) = "C" ;
                                   .AND. UPPER(.Item[ lnI ] ) = UPPER( tuValue )
                      lnElement = lnI
                      EXIT
             *     Search for any other data type or case sensitive search for
             *     a string.  
                  CASE VARTYPE( .Item[ lnI ] ) = VARTYPE( tuValue ) ;
                                  .AND. .Item[ lnI ] = tuValue
                 lnElement = lnI
                 EXIT
             ENDCASE

       NEXT

      *     If this is a two-dimensional array, convert lnElement to a “Row” subscript.
            *     A member’s “position” in a two-dimensional collection is the row it occupies in
            *     the Item[] array.

IF lnElement > 0 .AND. ALEN( .Item, 2 ) > 0
      RETURN ASUBSCRIPT( .Item, lnElement, 1 )
ENDIF
RETURN lnElement  

ENDWITH

Value():  Value () returns the contents of an item at the location in the collection specified by indices passed as parameters.  The syntax is,

Value[ nIndex₁ [, nIndex₂ ] ), 

where nIndex₁ points to the item and nIndex₂ to the position on the item.  If the specified location does not exist, .NULL. is returned.

*     Collection.Value()
*
*     OVERVIEW:   Returns the content of the member at the position specified in tnIndex.
*
*     PARAMETERS: tnIndex1    An integer representing the row location in the collection
*                             of the value to be returned
*
*                 tnIndex2    An integer representing the column location in the
*                             collection of the value to be returned.  Applicable only
*                             to a two-dimensional collection.
*
*     RETURN:     (U)         The value of the member at the location specified by tnIndex,
*                             if found, otherwise .NULL.
*

LPARAMETERS tnIndex1, tnIndex2 

WITH this 

      *     Test for a valid tnIndex1

      IF VARTYPE( tnIndex1 ) = "N" ;

.AND. BETWEEN( tnIndex1, 1, ALEN( .Item, 1 ) )     

            IF EMPTY( tnIndex2 )

*     If this is not a multi-positional collection, return the content of
*     the the item tnIndex1.           

                  RETURN .Item[ tnIndex1 ] 

            ELSE
                  *     If this is a multi-positional collection, return the content of the
                                    *     position pointed to by tnIndex2 

            RETURN .Item[ tnIndex1, 1 ]     

      ENDIF 

ELSE                       

            IF VARTYPE( tnIndex2 ) = "N" ;
                            .AND. BETWEEN( tnIndex2, 1, ALEN( .Item, 2 ) )                       
                  RETURN .Item[ tnIndex1, tnIndex2 ] 
            ENDIF 

      ENDIF     

ENDWITH 

RETURN .NULL. 

Conclusion 

And that is our Collection class.  Pretty simple really. 

You could add any number of enhancements.  A couple that come to mind immediately are a Count property that also returns the number of positions on an item and a Sort() method to place objects in a collection in order.    Having an impatient attitude about tools,  I only build as much of the tool as I need right now.  If more is needed later, it can be built then.  So far, I have had no call for a Sort() method or Count property that returns item positions. 

I make constant use of collections to gather objects that I need to process as a group.   They permit me to devise rather simple, and sometimes elegant, solutions to problems that would otherwise be very difficult to solve even with extensive code.  

Part 2,  will describe the use of our new collection class to solve a couple of real-world programming problems.

The first is a solution to the hanging form.  A hanging form occurs when an object outside of the form owns an object reference to the form or some object on the form.  The form cannot be closed until all of those outside references are destroyed.  We can use a collection keep track of the external objects that own references to the form or an object on the form.  When the form or object is destroyed, it tracks down and eliminates all of these external references.  No more hanging forms. 

The second problem is the OLE (ActiveX) control that absolutely refuses to pay any attention to your LockScreen setting.  If you read George Tasker’s article Smoother (Virtual FoxPro User Group, June 2000 Newsletter), you know that an ActiveX control on a form is not actually on the form, but is a separate window of its own.   The form is a window, the ActiveX is a window.  So when the form’s LockScreen is set to true, the ActiveX control ignores the setting because it does not consider itself a part of the form’s window.   In Part 2 we will use a collection to facilitate preventing OLE controls from repainting while a form’s LockScreen property is true. 

Happy coding. 

J. M. Edgar has been a software developer in xBase languages since 1984. He can be contacted on the Universal Thread or at jmedgar@yahoo.com.  

Copyright © 2001 Jurix Data Corporation.  All rights under copyright reserved.

   Back To Top

Where's the Marketing?

Software Development Agreements

J. M. Edgar, JD

   Back To Top

Microsoft KnowledgeBase

HOWTO Determine if a Service Exists Using Visual FoxPro

HOWTO Find Installed Modems with Visual FoxPro

INFO ILOVEYOU Virus Attacks FoxPro SCT Files

HOWTO Find the Day that Daylight Savings Time Occurs

How to Hide the FoxPro Run Command Window in Visual FoxPro

HOWTO Use the Windows Scripting Host to Automate an Application

HOWTO Create an Application Role on Microsoft SQL Server 7.0

HOWTO Set up a Visual FoxPro Internet Server

Vfp6int.exe VFP 6.0 ODBC Driver FoxPro.int Resource File

Vfpcom.exe Using COM Language Enhancements in VFP 6.0

HOWTO Set Up Source Code Control with Visual SourceSafe

INFO Time Difference in Checking Out vs. Getting File in SourceSafe

HOWTO Use OLE Automation with Visual SourceSafe

HOWTO Use a Project and File Object's SCC PEMs

HOWTO Synchronize a SourceControlled VFP Project Between Users

INFO Searching FoxPro Newsgroups

HOWTO Start Internet Explorer and Navigate to a URL Using OLE Automation

HOWTO Save and Restore Grid Column Order and Widths

How to Set Up Relationship in Data Env for Concatenated Fields

WhatsThisHelp.exe Implement HTMLHelp and WhatsThisHelp Concurrently

Example of Polymorphism in Visual FoxPro

INFO Description of the FOXTOUCH Function

Benefit of Storing Printer Info in a Report Table (.FRX File)

How to Access Report's Data Environment While the Report Runs

How to Modify a Report Preview Window Property

HOWTO Use Offline ADO Recordsets in Visual FoxPro

HOWTO Use COMCLASSINFO(2) to Check Installed ADO Version

HOWTO Simulate a Detail Band Longer Than One Page

INFO FoxPro Header Check to Determine if Table is Corrupt

INFO Programming in Reports w- Band Expressions on Entry-Exit

HOWTO Find the Full Path of an Executable Given the Extension

HOWTO Add Records with Memo Data Using the Visual FoxPro ODBC Driver

HOWTO Set Where .tmp Files Are Created with the VFP ODBC Driver

BUG Parameter Placeholders with Visual FoxPro (VFP) ODBC Driver and Large Tables

BUG OLE SUBCLASS Subclassing of OleControl-OLE Unspecified

BUG Fatal Error When Releasing a Converted FoxPro 2.x Form

BUG Visual FoxPro May Ignore DDE Messages

PRB Error Cannot Update the Cursor When You Modify Visual FoxPro Tables

PRB No Version Info if COM DLL-EXE Is Built Under Windows Me-98-95

PRB Application Appears Then Exits to Operating System

PRB Scrolling Message Record not available ... Please Wait

PRB Lockscreen with Assert Dialog Causes Problems with Controls

PRB ACTIVATE WINDOW Command Not Working for Toolbars

PRB BINTOC Fails with SET COLLATE TO GENERAL

PRB VBScript Type Mismatch Error When Field Type Is adNumeric

PRB Header Corruption Causes END TRANSACTION to Discard Appended Records

PRB Page Size of Embedded Word File Changes When Edited

PRB Application Unable to Edit Database Files

PRB BorderStyle Property May Prevent Taskbar from Appearing

PRB Error in Remote View Wizard When Connecting to DB2

PRB FoxPro Corruption Problems Fixed by Novell 3.11 Patches

PRB VBScript Type Mismatch Error When Field Type Is adNumeric

   Back To Top

Various MS Links

DLL Help Database	Microsoft
Windows XP Home Edition Comparison Guide	MS Windows XP
$49 Training (promotions-labs) labs	Microsoft Training & Services
Microsoft Windows Update - providing critical updates, security fixes, and software downloads	Microsoft
Internet Explorer 6 Public Preview	Microsoft
Managing Duplicate Microsoft System Management Server Unique Identifiers	MS TechNet
Scripting Clinic Scripting the Experience with Microsoft Office Developer	MSDN Online Voices
HOWTO: Use Visual Basic to List Active Logical Drives	Microsoft KnowledgeBase
HOWTO: Use Visual Basic or ASP to Create an XML Spreadsheet for Excel 2002	Microsoft KnowledgeBase
ACC2000 How to Programmatically Create, Search, Replace, and Modify Code	Microsoft KnowledgeBase
OL2000: (CW) How to Create a Server Side Rule to Auto-Reply with a Specific Message	Microsoft KnowledgeBase
WD97 How to Add a Portrait Page Number to a Landscape Page	Microsoft KnowledgeBase
ACC97 How to Repair a Damaged Jet 3.5 Database	Microsoft KnowledgeBase
Microsoft Train Simulator	Microsoft
Tackle Common Tasks With These HowTo Resources	MS TechNet
Microsoft Project Assessing and Managing Risks	MS Office Support
Chart Workspace Object Model	MSDN
Spreadsheet Object Model	MSDN
International Features in Microsoft SQL Server 2000	MSDN
Unchecked Buffer in ISAPI Extension Could Enable Compromise of IIS 5.0 Server	Microsoft Security Bulletin MS01-023
MSN Explorer 6.1	MSN
FP2000: Where to Obtain the Microsoft FrontPage 2000 Software Developer's Kit (SDK)	MS TechNet
Free Tool Downloads - Windows 2000 Resource Kit software tools	MS Windows 2000
Windows 95, updates, updating, downloads, service packs, communications, networking, power toys, kernal toys, preview, etc.	MS Downloads: Windows 95

   Back To Top

.NET

Visual Studio.NET Beta 2 Slated For June	Techweb News
Microsoft scales back changes in VB.Net	ZDNet eWEEK
Microsoft redrawing Visual Studio.Net	Tech News - CNET.com
Why .NET will not become Microsoft's next OS-2	TechRepublic
Microsoft opens tech center to nurture .Net	Computerworld News & Features Story
Seagate Software Crystal Reports® for the Visual Studio.NET Platform
Visual Studio.NET Comes Up Short	angrycoder.com
Microsoft Is All Talk About .NET	Forbes.com
Tuning up for C#	Tech News - CNET.com
Deciphering Microsoft's .Net puzzle	Network World Fusion, 04-16-01
Serving the Web Windows Forms in Visual Basic.NET	MSDN Magazine, April 2001

   Back To Top

XML

Web consortium adopts specification for XML definitions	Computerworld News & Features Story
Microsoft Releases SOAP Toolkit, XML Resources On MSDN	Computer Reseller News
What's New in the April 2001 Microsoft XML Parser 4.0 Technology Preview	MSDN
INFO List of Issues Fixed in Microsoft XML 3.0 Service Pack 1	Microsoft KnowledgeBase
Graphical XML editor gives developers added power	Intelligent Enterprise Magazine Product Review
Wall Street Releases Draft XML Standard	Computerworld Resources-Research Story
Data Junction Refreshes XML Portion of Integration Suite	Enterprise Magazine
Find a home for your XML data	idg.net
A Brief History of SOAP	XML.com  [Apr. 04, 2001]
Microsoft updates SOAP toolkit, further supports Web services standards	InfoWorld
Soap Toolkit 2.0 RC0	MSDN Online Downloads
Industry Closer To XML-Based Web Services Standards, IBM Says	Computer Reseller News
@court XML Lifts The Burden Of Paper	Techweb News April 9, 2001
A Quick Introduction to XML Schemas	iftech journal
XML: The Big Picture	Network Computing Feature Business Applications
XML Special Report: Dishing Up Dynamic Content	Network Computing Feature Business Applications
Web Consortium issues XHTML recommendation	Computerworld Resources-Research Story
XML: The Big Picture	Techweb News XML April 24, 2001
Intuition and Binary XML	XML.com [Apr. 18, 2001]
Using OPENXML	Microsoft
Retrieving and Writing XML Data	MSDN
XML Schema confounds the experts	ZDNet News
XML Beyond HTML	Sun Microsystems
XML schema catches heat	ZDNet eWEEK
XML Linking Language (XLink) Version 1.0	w3.org
Tutorials - XML messaging with SOAP	developerWorks Components Education
New XML image standard under development	InfoWorld
Extensible Markup Language: XML's Tower Of Babel	InternetWeek In Depth
Gorilla Tactics	Computerworld Resources-Research Story

   Back To Top

General Interest

Windows XP to ship in October	Tech News - CNET.com
It's Up To You To Pave The Way To The Information Society	InternetWeek Opinion Rash's Judgment
How To Write Unmaintainable Code
Enough With The Whining! Have you noticed which company is acting like there is no downturn in the technology sector?	ZDNet Interactive Week
Microsoft Linux - the premier linux distro
EU to turn US e-tailers into Euro tax gatherers	The Register
Why Windows XP really was worth the wait	ZDNet Story
1394 reasons to like Win XP	ZDNet eWEEK
WinXP: why it's the Big One that could make MS bigger yet	The Register
Windows XP, a.k.a. Whistler, impresses our reviewer	Windows 2000 Advantage - Columns
Analysts and users angry over Windows XP	vnunet.com
WinXP: product activation, updates and control freakery	The Register
Windows XP Hits Home	Wired News
M$ confirms WinXP won't support USB 2.0	The Register
Microsoft unplugs Intel project	ZDNet News
Microsoft reveals XP flavours and prices	vnunet.com
How will Windows XP affect Windows 9x	TechRepublic
WinXP falls over old Cisco bug	The Register
Update Cisco fixes switch-Windows XP problem that hit Xerox network	ComputerWorld News & Feature Story
Microsoft partner criticises .Net	vnunet.com
Microsoft trims hiring plans	Tech News - CNET.com
Microsoft offers commerce tools to FrontPage users	InfoWorld
Microsoft retools MSN Explorer	Tech News - CNET.com
Advertising Humor Is at Center of Microsoft's New Campaign	NY Times (Registration Required -- Free)
MS ridicules itself to sell Office XP	The Register
Office XP test drive almost free	Tech News - CNET.com
Microsoft, Windows 95, Windows NT, DOS Microsoft Phasing Out Support for Old Software	Internet Week
Office 95 doesn't make the upgrade	Tech News - CNET.com
Some managers are not worried about losing Win95 support	TechRepublic
Microsoft, Windows 95, Windows NT, DOS-- Microsoft Phasing Out Support for Old Software	Internet Week
Where's NT 4 Service Pack 7?	Enterprise Magazine
Microsoft Cancels Windows NT 4.0 SP7	Wininformant.com
Exploit devastates WinNT/2K security	The Register
What's All the Fuss About?  -- At the heart of Windows 2000 is essentially a database - the Active Directory.	ENT Article Archive
Microsoft alters Passport Terms to stem Hotmail defections	The Register
Microsoft alters Passport terms of use	InfoWorld
MS Revises Passport Terms	Wired News
Developer of Notes apps embraces Exchange	ZDNet eWEEK
IE6 beta bug can blank out email	The Register
Microsoft reshuffles executives, creates separate .Net group	Computerworld News & Features Story
Specialist IE, Windows can mask dangerous files	InfoWorld
HTML bug hits Internet Explorer	vnunet.com
Millions of IM users go dark	ZDNet News
AOL Instant Messaging service out again	InfoWorld
VC veteran named to White House tech council	ZDNet eWEEK
Microsoft a year later Has anything changed	ZDNet News
Internet Critic Takes on Microsoft	NY Times (Registration Required -- Free)
Windows tech: 10 steps to creating an active directory	Computerworld Resources-Research Story
More programmers going Extreme	Tech News - CNET.com
Programmers adopt 'Extreme' methods	ZDNet News
White Paper: How to get Custom Software to market in 8 weeks or less: Applying the principles of Extreme Programming for business success	Geneer
Programming gets extreme	Computerworld News & Features Story
MIT Short Circuits Distance-Ed Sellers	Forbes.com
Lack of standards blocks supply-chain automation	Computerworld Resources-Research Story
My life as a cable and DSL guinea pig--and what I learned	ZDNet Story
Why you should be using FireWire	ZDNet News
When Is Software Ready Ship it Anyway!	MSDN
Volvo Delves Into Web-based Car Design	Computerworld Resources-Research Story
Philippe Kahn is never at a loss for a technology idea	The Net Economy
Despite layoffs, the labor market it still tight	The Net Economy
Tuning up Windows 98: Nine tips that are often overlooked	TechRepublic
KBINF OLEDB Connect Info from ODBC	AccessHelp.net
KB009: Shape Captions Made Easy
Stop the OS insanity	ZDNet News
Linux founder trashes Mac OS X foundation	Tech News - CNET.com
MacOS X is 'crap' - Torvalds	The Register
Apple & Microsoft Déja vu all over again	ZDNet News
Core OS differences from Apple	ZDNet eWEEK
Don't blame me, I'm only the operating system	Windows 2000 Advantage - Columns
Microsoft licenses speech-recognition technology	InfoWorld
Perfecting Your Professional Pitch	MSN Careers
There's No Foolin' In E-Commerce Transactions	Computerworld Communities Story
Police Policed With Data Mining Engines	Computerworld News & Features Story
Involve the user-- A better way to develop	TechRepublic
Automated Clearing House	Computerworld Resources-Research Story
Find Registry Facts Fast	ZDNet -- PC Magazine Solutions
An e-Tailer's Guide to Credit Card Processing	DevGuru Tutorials
Back to school with a vengeance You need to brush up on security. Hacker classes are now in session. Should you attend?	ZDNet Sm@rt Partner
Windows Insider NAT Expands the Net	MCP Magazine
All You Need Is Bandwidth	Computerworld Resources-Research Story
Bandwidth Constraints Begin to Worry Schools	NY Times (Registration Required -- Free)
Protect your always-on Internet connection from intruders	ZDNet Story
INTERNET CONNECTION SHARING A three-part series on sharing your broadband connection. Part 1: Overview Part 2: Software Part 3: Hardware	TechTV
ADSL Tutorial	The Net Economy
Broadband Dreams Deferred	Network Computing Top of the Stack Network & Systems Infrastructure
DSL on the rise	Techweb News April 6, 2001
Digital Subscriber Line (xDSL) FAQ	The Net Economy
A cell phone that beats DSL Why this changes everything	ZDNet Story
The Downside Of DSL, Cable Modems	Information Week
DSL Sharing	TechTV
Get the Most Out of Your Broadband Connection	TechTV
Use Proxy Software to Share a Broadband Connection	TechTV
WinProxy for Home Users - Home Page	Ositis Software
WinGate - Internet Sharing-Proxy Server Solution	Deerfield
Why Wireless Needs a Hard Look	Computerworld News & Features Story
802.11 and swiss cheese	ZDNet News
Wireless Short Message Service (SMS) Tutorial	The Net Economy
Integrating wireless technology	digitalMASS at Boston.com
Using ASP to Send a Wireless Text Message	15 Seconds
War driving by the Bay	The Register
Can Ethernet be stopped?	ZDNet Sm@rt Partner
Five NetMeeting Secrets	TechTV
UML for the Whole Lifecycle The second half of a look at Rational Rose 2001 and the AnalystStudio suite	Intelligent Enterprise magazine
How To Harness Distributed Object Architectures (Page 1)	Network Computing Workshop Network & Systems Infrastructure
Adobe Acrobat Reader 5 - Download	Adobe
Net Hail for Windows NT - GUI interface to NET SEND command
RealPopup homepage -- Freeware WinPopup Replacement
BootDisks - CDrom Files -Quality Utilities And Tools	BootDisk.com
Color Cop	ZDNet - PC Magazine PC Labs
Startup Control Panel	Mike Lin's Home Page
ADO Explorer 1.51-- adox151d.exe Is a powerful database tool using ADO (ActiveX Database Objects) that allows you to proceed quickly and efficiently in your everyday database work. Now comes with ready to use native SQL commands for MSSQL, ORACLE and INFORMIX servers!	Programmers Heaven - Where programmers go!
Serial Communication library for Win32 (event-driven or not) V1.0 - serial.zip The package contains the source of two files describing how to interface the serial port for Win32 applications. The modules presented can work either in event-driven application (GUI,...) or in non-event-applications (like console application).	Programmers Heaven - Where programmers go!
Directory Report -- wdir.zip Is the file manager for Windows 9x/NT/ME/2000. Easy to use and packed full of features, Directory Report has something to offer for everyone.	Programmers Heaven - Where programmers go!
IE_NAV_REF.zip -- A list of key objects, properties and methods and their Availability across MSIE and Netscape Navigator	Programmers Heaven - Where programmers go!
MS Agent Info (Zip file)
Symantec Unleashes 7.0 Version of Ghost	Enterprise Magazine
AppendPDF -- Create One PDF From Many	Appligent
Connectix previews virtual Windows, Linux even OS/2 tech.	The Register
New version of Zone's firewall on the way	ZDNet eWEEK
Registry Healer	KsL Software
Products - Annotation OCX SDK	Black Ice Software Inc.
Wintellect - Free Tools	Wintellect
Lucent NetworkCare - MyVitalAgent (Free Tool Download)	Lucent Services
Fill that toolbox before tackling Active Directory	Network World Fusion
Web Tip: Add Functions to IE 5	TechTV
Shell Scripting 101, Lesson 1	Windows Scripting Solutions Online
Using the Counters Object	4GuysFromRolla.com
Connections And Server Database Permissions	PowerASP.com
COM Caffeine for your ASP Lesson 1 :  Introduction to ASP/COM	FindTutorials.Com
Transfer Video to CD	TechTV
Moving Molecules With Nanotechnology	TechTV
Paperback Music One Solution to the MP3 Debate	N.Y. Times (free registration required once)
Download our RJ-45 module installation guide	TechRepublic
Plextor PlexWriter 16-10-40A	TechTV
Disable Onboard Video Card	TechTV
Dual Monitors	TechTV
Get Rid of Your Windows 98 CD	TechTV
Sharing an Internet Connection	TechTV
Visualizing Change "solid modeling" CAD/CAM software	InternetWeek Transformation Today
MS SQL Server: Dynamically manipulating files using xp_cmdshell	searchDatabase.com The Database Specific Search Engine
What you don't know about denormalization can hurt you, Part I	searchDatabase.com
Database Tips - Key database design concepts	searchDatabase.com
Best Database Web Links - ADO, OLEDB	searchDatabase.com
Working with Databases and International Date Formats	4GuysFromRolla.com
Tracking SQL Server crises: Configuring automatic alerts	TechRepublic
SQL Server: Inserting Images ( binary data ) into Database	stardeveloper.com
SQL Server: Tame Those Strings Part 5 - Using STUFF	SWYNK.COM
MSDE - Desktop Engine	SWYNK.COM
Queries On Multiple Databases	SWYNK.COM
SQL7 Replacement for Access Crosstab RAC, the R(eplacement) for the A(ccess) C(rosstab) query, written exclusively for MS Server 7 and S2k
Oracle PL/SQL -- The Complete Video Course: 1/e	Welcome to the DigitalGuru Computer Bookshops
Access Reports on the Web - Stupid VB Tricks	accesshelp.net
Programmatically changing a user's Windows password with Visual Basic	TechRepublic
Win2K Task Scheduler	Windows 2000 Magazine
Registry Secrets	Windows 2000 Magazine
10 steps to creating an active directory	ITworld.com - Windows tech
Get Rid of Your Windows 98 CD	TechTV
Chase Away WinMe Annoyances	TechTV
In space, no-one can fix Windows NT	vnunet.com
So You Want to Be a Rocket Man	MSN Careers
Understanding DCOM - Part I	iftech journal
Understanding DCOM - Part II	iftech journal
Understanding DCOM - Part III	iftech journal
PostScript Programming	DevCentral Learning Center
EC Tips: Mail and Purge	internet.com's Electronic Commerce Guide
What Is Internet Addiction?	TechTV
Dramatic increase in virus attacks predicted	ZDNet Story
Field of screams You wouldn't know it from the shouting match, but Windows 2000 and Linux can play side-by-side in the same league. Here's how.	ZDNet Sm@rt Partner
Preparing for Linux in your enterprise	TechRepublic
Linux worm attempts to take over insecure servers	The Register
Adore worm squirms in Linux systems	Tech News - CNET.com
New worm targets unprotected Linux systems	Computerworld Resources-Research Story
Virus Threat to Linux Low	Internet Week Security Experts April 6, 2001
NSA funds work to thicken Linux armor	Tech News - CNET.com
You can't always get what you font (Linux)	ZDNet News
Sony releases Linux for Playstation2	The Register
Peace, love and...Linux	ZDNet News
Apache 2.0 beta hits the Web	Computerworld News & Features Story
Holes found in file server software	Tech News - CNET.com
Flaw found in common Internet standard	Tech News - CNET.com
FTP software open to attack	ZDNet News
FTP software flaw could allow remote attacks on servers	Computerworld News & Features Story
Transferring Files Be Careful	Wired News
Big Blue hacker for hire	ZDNet Sm@rt Partner
3Com Beware The Inner Enemy	ZDNet Interactive Week
Demand for IT workers is down 44%, study says (4-01-2001)	SiliconValley.com
Tech recession to bottom-out in a year - Marimba CEO	The Register
Live mouse found inside PC	The Register
Work at light speed--try some simple time-saving tips	ZDNet Story
Slot Car Tracks Meet The Computer Age	Speedvision Online
Adobe moves toward network publishing	InfoWorld
AGP Versions	TechTV
Finding Time to Think	Computerworld Resources-Research Story
Keeping Workers Revved Up During Tough Financial Times	Computerworld Resources Story
ADO.NET and Access 2002	Smart Access May 2001 - Editorial Changes
Tech ageism works both ways	Tech News - CNET.com
Experts: computers slouching towards usability	Computerworld News & Features Story
Apple - Trailers - The Dish	Apple
Taxing Overhaul IRS standardizing data, access in $10 billion gamble	InternetWeek Apr. 19, 2001
Biggest waste of worker's time--e-mail	ZDNet News
Fly brain software takes to the sky	The Register
'Tractor beam' technology advances	BBC News SCI-TECH
Making HAL Your Pal	Wired
New Chip Prevents Car Thefts	MbizCentral, Gateway to the Mobile Economy
Spycam Small Enough for Mobile Devices	MbizCentral, Gateway to the Mobile Economy
Let's get visual! Why you absolutely need to get a Webcam	ZDNet Story
Guest Opinion: Cross the Other Digital Divide	Visual Basic Programmer's Journal

   Back To Top

TIPS 'n TRICKS

By the Membership

GenLoader - A WSH Loader Wizard

Application	GenLoader.SCX
Purpose	The purpose of GenLoader is to allow you to easily create WSH scripts to update an application executable by using one of two means to check currency.
Requires	Microsoft Visual FoxPro 6.0 or better
	GenObjs class library (included)
	Open bitmap (included)
Authors	John Koziol, MCSD, MVP
	(850) 893-2302
	digitalelite@earthlink.net
	George Tasker, MVP
	GTasker@compuserve.com
Version	1.00 (April 21, 2001)
Copyrights	GenLoader ã2001, John Koziol
	WSH Loader FAQ, ã2001, George Tasker

Download GenLoader.zip

   Back To Top

---

Benchmarking: Microsoft Visual FoxPro 6.0 vs. Inprise Delphi 5

I know that all of you would be interested in this kind of benchmark. I was
too until I got the chance to do it. As a student, you get the chance to meet
people and PEOPLE. I started to work in database programming since I was a
child (5th grade) and I was always interested in benchmarking software
like you too (I think).

I made 4 tests:

I used 2 identical computers (P II 233, 128 MB) and a programmer in Delphi
offcourse (I don't know a thing in Delphi).

We used two tables with 1,000,000 records. In the Delphi (ISAM) table we
used a float field NOT autoincremented-- in the FoxPro one I used a 7 numeric
field long.

We then made some code that will increment the two fields and started the test. We
made the adding code in two ways - append and Insert.

In the append method, FoxPro was adding about 2291 records per second and
Delphi about the same (2154).

In the insert method FoxPro was adding about 8851 records per second and
Delphi about (4456).

So as you see FoxPro is better at doing Inserts than Delphi.

Then we tried the same test but we added a MySQL server.

We couldn't measure the time because my neighbors (also students on the
campus) were playing games on the network and the results where random.
Once Fox was faster and after one minute FoxPro worked like a snail. The same
with Delphi.

In the end of the test, we drank some beer and got drunk.

[Ed. Note:  Please don't drink and test.  Do your testing first.]

Well, Delphi is superior in multimedia and stuff like that.  But, if you need
speed, you will have it only with FoxPro.

Ionut D. Baldazar

Phone: +4093026686
E-mail: ionutb@c3.campus.usv.ro

   Back To Top

---

Visual Class Navigators Library

The library of visual classes Navigators contains three simple classes - CKhFullNavigator, CKhMidiNavigator and CkhMiniNavigator. These classes are developed for creation of typical managing and navigating sets of buttons for forms.

Download Navigators.zip

Alexander Khudyakov
mailto:akhudyakov@yahoo.com

   Back To Top

---

How Can I Color Code Records/Cells In A Grid?

If you want to add colour coding to a grid to be able to visually differentiate between records and/or cells, add 2 new fields (fore_color C(11), back_color C(11)) to the ControlSource table of Grid1.

Add a new form method called .GridColours() and a new form property called .nRecNo.

In the .Init event of Grid1 put:-

THISFORM.nRecNo = RECN([TABLENAME])
THIS.Refresh()

In the .AfterRowColChange event of Grid1 put:-

THISFORM.nRecNo = RECN([TABLENAME])
THIS.Refresh()

In the .Column(s) of the grid set .Sparse = .F. and .DynamicCurrentControl = THISFORM.GridColours().

In the .GridColours() method put:-

WITH THISFORM.Grid1
    DO CASE
    CASE THISFORM.nRecNo = RECN([TABLENAME])
        .Column1.Text1.Forecolor = RGB(255,255,255)
        .Column1.Text1.Backcolor = RGB(0,0,128)
    CASE TABLENAME.fore_color = [R/W]
        .Column1.Text1.Forecolor = RGB(255,0,0)
        .Column1.Text1.Backcolor = RGB(255,255,255)
    CASE TABLENAME.fore_color = [B/W]
        .Column1.Text1.Forecolor = RGB(0,255,0)
        .Column1.Text1.Backcolor = RGB(255,255,255)
    CASE TABLENAME.fore_color = [G/W]
        .Column1.Text1.Forecolor = RGB(0,0,255)
        .Column1.Text1.Backcolor = RGB(255,255,255)
    ENDC
ENDW

You will find the .Forecolor properties of the cells will reflect the value selected by TABLENAME.fore_color, with the currently selected record highlighted.

If you want the fields TABLENAME.fore_color and TABLENAME.back_color to determine the colours displayed, then :-

    DO CASE
    CASE ALLT(TABLENAME.fore_color) = [255,255,0]
        lcColor = [.Column1.Text1.Forecolor = RGB(]+ALLT(TABLENAME.fore_color)+[)]
        &lcColor
        lcColor = [.Column1.Text1.Backcolor = RGB(]+ALLT(TABLENAME.back_color)+[)]
        &lcColor
    ENDC

Chris R. Chamberlain
support@lithoplas.com

   Back To Top

---

Set Your Exe's Start Path On The Fly

Forget about the problems caused by shortcuts badly created. With this line
of code your exe will always start in the directory from where it was
called. I think that this line must be the headed one of any program.

If Version(2) = 0 THEN
Cd (LEFT(SYS(16),AT('\',SYS(16),OCCURS('\',SYS(16)))-1))
ELSE
*-- may be here you want to set your development environment...
ENDIF

Ponga su directorio de inicio facilmente

Olvidese de los problemas causados por accesos directos mal creados.
Con esta linea de codigo tu exe siempre se parará en el directorio desde
donde se llamó.
Yo pienso que esta linea debe ser el encabezado de cualquier programa.

If Version(2) = 0 THEN
Cd (LEFT(SYS(16),AT('\',SYS(16),OCCURS('\',SYS(16)))-1))
ELSE
*-- Aqui tal vez quiera setear su entorno de desarrollo...
ENDIF

Ariel Gimenez
arielgimenez@yahoo.com
Argentina

   Back To Top

---

VFPLife.zip - A VFP6 Mathematical Game

Application	Life.SCX (the Life Form)
Introduction	Life was invented by the mathematician John Conway in 1970. Conway wanted to create a simple set of rules that defined the evolution of patterns. He was successful; Life starts with very simple patterns and only a handful of rules and can generate complex, beautiful, and sometimes unpredictable patterns. The rules are easy:  A cell that is turned on is alive; others are not. Each cycle, all surrounding cells are evaluated. If a cell had one or no neighbors, it dies. If it has three living neighbors, it stays alive. If it has 4 or more living neighbors, it dies. An empty cell becomes alive (is born) if 3 neighbors are living. These rules are evaluated for the matrix as a whole and then plotted.  And reevaluated, replotted…and so on. To quote astrophysicist Mario Livio from his book, The Accelerating Universe, “The moral from this game is simple: even with a very simple set of fully deterministic laws, an evolving system can achieve a high level of unpredictablility and complexity.” Numerous computer programs have been written to play Life. Life was one of the very first programs I ever wrote on an Apple ][ in the late 1970s.
Requires	Microsoft Visual FoxPro 6.0 or better
	Lifeforms class library (included)
Author	John Koziol, MCSD, MVP
	(850) 893-2302
	digitalelite@earthlink.net
Version	1.00 (April 14, 2001)
Copyrights	ã2001, digital elite services and John Koziol

Download VFPLife.zip

John Koziol, MCSD, MVP
digitalelite@earthlink.net

   Back To Top

---

Copying Files?

Source: http://www.kicken.com/images/copy.gif

   Back To Top

---

Joke of the Month

Comments area

I've been a member of VFUG now since October of 1997. I really like this place with all of the many different countries of the world represented here. It never ceases to amaze me how many different ideas pass through this website and people are always willing to share what they know with others. When I was asked about Microsoft's marketing of Visual FoxPro over the last few years, I quickly replied, "I can't believe it's not better!"  Long live Visual FoxPro! Fabio International Celebrity Residence: Can't Tell You

   Back To Top

ON SHUTDOWN....

Some final comments....

Generally, regular CHAT sessions are held every Thursday.  For more information on scheduled chat sessions here at VFUG, contact John@VFUG.Org or check the VFUG newsgroup out for current info.

Want to be (in)famous? All you have to do is send VFUG an article or otherwise useful piece of content. We'd be happy to publish most Fox related tidbits, and you can help your fellow developers worldwide!

VFUG is also always looking for additions to our Vendor program. Would your company be interested? Contact Carl@VFUG.Org to get with it.  Also, if you are interested in your company placing a banner advertisement on our home page, please contact Carl.

   Back To Top

Virtual FoxPro User Group Copyright © 2001, Virtual FoxPro User Group, Orlando (Florida), All Rights Reserved