I want to use Treenodes with my own objects and have declared them like this:

MyObject1 = class(TTreeNode)
 aValue1 : integer; 
Public
 constructor Create(Owner: TTreeNodes);
 procedure .......
end;

MyObject2 = class(MyObject1)
 aValue2 : integer;
 public
 constructor Create(Owner: TTreeNodes);
 procedure ......
end;

In the TreeView.OnCreateNodeClass event, I set:

NodeClass := MyObject2;

When I then create a new node in my tree with:

TreeNode := TreeView1.Items.AddChild(ParentNode, '');

I believed that MyObject2.Create would be called, but it is not. The MyObject2 is created as it should, so I can access the fields aValue1 and aValue2 when the node is created, but I would like to initialize them in my constructor.

Anyone have any idea about this?

CodePudding user response：

You need to add override to each of your constructors to ensure that they will be called. You must also make sure that you call inherited in each constructor implementation.

The MyObject2 is created as it should so I can access the fields aValue1 and aValue2 when the node is created but I would like to initialize them in my constructor.

I don't think that is true. I think that when you try to access those fields you will just be accessing some random part of memory that is outside the actual node instance.