Author: Jonas Bilinkevicius

I have a form that creates an advanced SQL string and I am trying to stream the 
entire form (TAdvanced) to disk in order to save the state of the form, and then be 
able to easily recall it later without having to decode the SQL string. However, 
after successfully (I think) streaming it to disk, I get the error "A component 
named PageControl1 already exists". I have tried all kinds of variations on this, 
but there always seems to be some conflict - either TAdvanced can't be assigned to 
TAdvanced or the current, or others. Any suggestions would be appreciated. Do I 
need to manually iterate through the components of the form and write each one in 
turn to the stream?

Answer:

I would use Read/ WriteComponentResFile with code similar to:
1   
2   constructor TFrmPersistent.Create(AOwner: TComponent);
3   begin
4     if FileExists('Persistent.xGS') then
5     begin
6       inherited CreateNew(AOwner);
7       ReadComponentResFile('Persistent.xGS', self);
8       self.Visible := false;
9       FormCreate(self);
10    end
11    else
12      inherited Create(AOwner);
13  end;
14  
15  procedure TFrmPersistent.FormDestroy(Sender: TObject);
16  begin
17    WriteComponentResFile('Persistent.xGS', self);
18  end;