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Mailing lists / lazarus / 2010-11

object casting to pointer

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Marco Aurelio Ramirez Carrillo

Hi.
I'm working witha TTreeview, and trying to assign a object to a TTreeNode.data property:

<code>
MyTreeNode := myTreeview.add(nil, "MyTreeNode");
// any "TObject" descendant class
MyObject = MyClass.Create();
// all of these, generate a syntax/semantic error:
// no typecasting
MyTreeNode.Data := MyObject;
// typecasting lowercase
MyTreeNode.Data := pointer(MyObject);
// typecasting capital
MyTreeNode.Data := Pointer(MyObject);
// typecasting with address operator
MyTreeNode.Data := pointer(@MyObject);
</code>

But none of them seems to work.
I already search in the wiki. Any idea, what is missing ?

Thanks.

stardev tod maramirezc ta gmail tod com

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Leonardo M. Ramé
to Marco Aurelio Ramirez Carrillo
Marco Aurelio Ramirez Carrillo wrote 29 lines
Hi. I'm working witha TTreeview, and trying to assign a object to a TTreeNode.data property: <code> MyTreeNode := myTreeview.add(nil, "MyTreeNode"); // any "TObject" descendant class MyObject = MyClass.Create(); // all of these, generate a syntax/semantic error: // no typecasting MyTreeNode.Data := MyObject; // typecasting lowercase MyTreeNode.Data := pointer(MyObject); // typecasting capital MyTreeNode.Data := Pointer(MyObject); // typecasting with address operator MyTreeNode.Data := pointer(@MyObject); </code> But none of them seems to work. I already search in the wiki. Any idea, what is missing ? Thanks. stardev tod maramirezc ta gmail tod com

I did a quick test using this:

TreeView1.Items[0].Data := @MyObject;

And it compiled without problem.

Leonardo M. Ram? http://leonardorame.blogspot.com

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Mattias Gaertner
to Marco Aurelio Ramirez Carrillo: Hi. I'm working witha TTreeview, and trying to assign a object to a TTreeNode.data…
Show quoted text 14 lines
Hi. I'm working witha TTreeview, and trying to assign a object to a TTreeNode.data property: <code> MyTreeNode := myTreeview.add(nil, "MyTreeNode"); // any "TObject" descendant class MyObject = MyClass.Create(); // all of these, generate a syntax/semantic error: // no typecasting MyTreeNode.Data := MyObject;

This works here.
Please provide a more complete example.

Show quoted text 5 lines
// typecasting lowercase MyTreeNode.Data := pointer(MyObject); // typecasting capital MyTreeNode.Data := Pointer(MyObject); // typecasting with address operator

Pascal types are case insensitive.

MyTreeNode.Data := pointer(@MyObject);

Simply wrong.

Mattias

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Michael Van Canneyt
to Marco Aurelio Ramirez Carrillo: Hi. I'm working witha TTreeview, and trying to assign a object to a TTreeNode.data…
Marco Aurelio Ramirez Carrillo wrote 14 lines
Hi. I'm working witha TTreeview, and trying to assign a object to a TTreeNode.data property: <code> MyTreeNode := myTreeview.add(nil, "MyTreeNode"); // any "TObject" descendant class MyObject = MyClass.Create(); // all of these, generate a syntax/semantic error: // no typecasting MyTreeNode.Data := MyObject;

I do this every day ? What is the error you get ?

Michael.

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