Author: Lou Adler

I miss one thing in frames: The ability of performing some initialization code as I 
would do in a TForm.OnCreate. So what would be the equivalent for frames?

Answer:

You can override the constructor for example. An alternative is to override the 
SetParent method and do the initialization after calling the inherited method. This 
way the frame will have a parent and you can then do things that require a window 
handle without running into problems. I use a base frame class in my current 
project that has this feature build in. The relevant parts are given below. In 
descendents I just override the Initialize method.

1   { ... }
2   type
3     {The base class for frames}
4     TPLC_BaseFrame = class(TFrame)
5     protected
6       procedure SetParent(aParent: TWinControl); override;
7     public
8       procedure Initialize; virtual;
9       procedure UnInitialize; virtual;
10      destructor Destroy; override;
11    end;
12  
13  procedure TPLC_BaseFrame.Initialize;
14  begin
15    {Override as needed in descendents}
16  end;
17  
18  procedure TPLC_BaseFrame.UnInitialize;
19  begin
20    {Override as needed in descendents}
21  end;
22  
23  procedure TPLC_BaseFrame.SetParent(aParent: TWinControl);
24  var
25    oldparent: TWinControl;
26  begin
27    oldparent := Parent;
28    inherited;
29    if (oldparent = nil) and (aParent <> nil) then
30      Initialize;
31  end;
32  
33  destructor TPLC_BaseFrame.Destroy;
34  begin
35    Uninitialize;
36    inherited;
37  end;