SetData pointer facility for Dialog list structures (List, Combo, Selection)

From: Wijck, Bart van <"Wijck,>
Date: Tue, 31 Aug 2004 11:59:10 +0200

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Hi BlackBox users,

When using tree dialog there's the Dialog Setdata procedure which allows one
to associate some data with a particular tree node:

 PROCEDURE (tn: TreeNode) SetData (data: ANYPTR), NEW;

I found this very useful when for example I display a tree with values which
are composite keys. If I select a node I can only retrieve a string:

        VAR
                sn : Dialog.TreeNode;
        :
        BEGIN
                sn := DlgTree.Selected();
                sn.GetName(SelectedString); (* only give me the composite
string, not the record with the key fields *)
but
                r := sn.Data();

directly gives the pointer to the record with the key fields previously
linked with SetData. So I can then easily check the database with the
composite key values, e.g. to see if the selected key still exists.

So far so good. One would have expected the same SetData pointer facility
for List structures (List, Combo, Selection). But there you can only get the
index value of the selected item (via GetItem). So if you typically build up
such a dialog list structure from a linked list with a composite key record
items, then after selection you again only have a selected string. To find
the real composite key you need run down the whole linked list until the
it's ordinal value matches the index values. Simple enough, but a bit
clumsy.

Easily resolved ofcourse if you use an array to fill the dialog list
structure (i.e. the selected index is the index value in the array).

However there must be many instances where the length of the list is
dynamic. So using a SetData pointer facility would be the trick. A
suggestion for improvement?

Regards, Bart

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Received on Tue Aug 31 2004 - 11:59:10 UTC