[AccessD] When is a collection not a collection?

I was thinking along the same lines because of the name/value association with properties.  A collection doesn't really have a place to store the name except in the key which is not returnable by default (yes you can write your way around this shortcoming but it's not the natural nature of a collection).  Storing objects in the collection would allow you store both.

Jim DeMarco

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com]On Behalf Of
DWUTKA at marlow.com
Sent: Tuesday, October 25, 2005 2:23 PM
To: accessd at databaseadvisors.com
Subject: Re: [AccessD] When is a collection not a collection?


A couple of thoughts on this JC.  First, a property really isn't an object.

Let's say you had this for a class:

Public SomeValue As Long
Property Get MyTextValue() As String
MyTextValue = "Something"
End Property

Now, if I were to do this:

Dim MC As MyClass
Dim lCol As Collection
Set lCol = New Collection
Set MC = New MyClass
lCol.Add MC.MyTextValue
Set lCol = Nothing
Set MC = Nothing

I'm not really adding the MyTextValue 'Property' to the lCol collection.
I'm just adding the value of that property.  The property isn't an object,
it's only a property of an existing object, not really 'child objects' in a
collection.  The collection you can use 'Properties' is just a
representation of those properties, not really a collection of child
objects.

I wrote a project a while back, which is an add-on for VB, that would create
a 'Properties' 'collection' for a Class.  Because when you have a custom
class, you can't say 'MyClass.Properties("SomeProperty")=1', at least not
without actually coding a 'Properties' class.  So I wrote a project that did
just that, it built a Properties class for you.

So I wonder if the Properties collection in the DAO objects is similar to
that, not a real collection, but simply a 'coded' method of being able to
'refer'/'cycle through' or soft code the properties of the object?

Drew



-----Original Message-----
From: John Colby [mailto:jwcolby at colbyconsulting.com]
Sent: Tuesday, October 25, 2005 12:41 PM
To: 'Access Developers discussion and problem solving'
Subject: [AccessD] When is a collection not a collection?


When it is a properties collection?

Try dimming a collection

Dim lcol as collection

Then try setting that collection to any DAO object's properties collection:

	set lcol = MyFld.Properties

Or 	
	set lcol = MyTDF.Properties

You will get a run time error: "Type Mismatch"

Sigh.

AFAICT, all of the other object collections in the database container - the
tabledefs, fields, forms etc are all true collections, i.e. you can dim a
collection and save a pointer to these object collections in your
collection.  Not so with the Properties collection of any object.

Sigh.

The properties collection has different properties and methods:

Append 
Count 
Delete
Refresh

John W. Colby
www.ColbyConsulting.com 

Contribute your unused CPU cycles to a good cause:
http://folding.stanford.edu/


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