Trevor
I think if you look at the examples you'll see a version using
a pointer to an object, all you do is free it on the nodefree event (IIRC)
Neven MacEwan (B.E. E&E)
Ph. 09 621 001 Mob. 0274 749062
Trevor Jones wrote:
Yeah, that would make sense, but the virtual tree only allocates as much
memory as is required by the GetNodeDatasize method, and that chunk is
inherently a record. Its a weirdness of the Virtual tree.
----- Original Message -----
From: "Neven MacEwan" <[EMAIL PROTECTED]>
To: "Trevor Jones" <[EMAIL PROTECTED]>; "NZ Borland Developers Group -
Delphi List" <[EMAIL PROTECTED]>
Sent: Monday, June 14, 2004 6:56 PM
Subject: Re: [DUG] Record inheritance
Trevor
Why don't you use a TObject descendant and
point the VirtualTree node at that (rather than a record)
Neven MacEwan (B.E. E&E)
Ph. 09 621 001 Mob. 0274 749062
Trevor Jones wrote:
I think I should be able to do this without asking for help, but
sometimes
the old brain just gets stuck.
I'm using a virtual tree to display and edit some data.
Each node has some data associated with it, and I use a record and a
pointer
to that record to get the data.
If you are used to using Virtual Trees, you will know what I mean.
I've subclassed the form, overridden then GetNodeDataSize method, but
since
the Tree.GetNodeData method always refers to a pointer to a record, I'm a
little bit stumped on how to add some extra fields to that record.
e.g.
TOriginalNodeData = record
id : integer;
value : double;
end;
pOriginalNodeData = ^TOriginalNodeData;
Then with my subclass, the node data looks like this:
TNewNodeData = record
id : integer;
value : double;
valueInherited : boolean;
end;
But this means that I have to re-declare all of the old fields in my new
record, and if the original record changes, things are going to go BANG.
I can declare
TNewNodeData = record
OldStuff : TOriginalNodeData;
valueInherited : boolean;
end;
and this works, but means I have to dereference OldStuff all of the time.
I'm sure that variant records should allow me to do what I want, but I'm
really stuck on how to declare it.
Any ideas?
Trevor
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