Delphi 6 create new form with constructor - delphi

Question

I am new to Delphi and have a problem with creating a new form dynamically. I want to create the new form with the elements properties from the gui I made. Here is the form I want to dynamically create :
unit AddEmployeeF;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, Buttons;
type
TAddEmployee = class(TForm)
GroupBox1: TGroupBox;
AddName: TLabel;
AddDept: TLabel;
AddPhone: TLabel;
AddExtension: TLabel;
AddDetails: TLabel;
Edit1: TEdit;
Edit2: TEdit;
Edit3: TEdit;
Edit4: TEdit;
Edit5: TEdit;
BitBtn1: TBitBtn;
BitBtn2: TBitBtn;
procedure CancelButtonClick(Sender: TObject);
private
{ Private declarations }
public
constructor CreateNew(AOwner: TComponent; Dummy: Integer = 0); override;
end;
var
AddEmployee: TAddEmployee;
implementation
{$R *.dfm}
constructor TAddEmployee.CreateNew(AOwner: TComponent; Dummy: Integer = 0; Detail : String);
begin
inherited Create(AOwner);
AddDetails.Caption := Detail;
end;
procedure TAddEmployee.CancelButtonClick(Sender: TObject);
begin
self.Close;
end;
end.
I dont want to create all the gui elements again in the constructor, just to modificate some properties of the elements, like caption but keep the positions and other properties from the gui definition. It's possible? And how to create the form from another form, like this? :
procedure TWelcome.SpeedButton1Click(Sender: TObject);
var
myForm :TAddEmployee;
begin
myForm := TAddEmployee.CreateNew(AOwner, Dummy, Details);
myForm.ShowModal;
end;

Answer 1

You overrode the wrong constructor. The TForm.CreateNew() constructor bypasses DFM streaming, so all of your design-time components will not be created at run-time. Worse, your overridden CreateNew() constructor is calling the inherited TForm.Create() constructor, which calls CreateNew() internally, thus you will get stuck in an endless loop that causes an stack overflow error at runtime.
To do what you are asking for, override the TForm.Create() constructor instead, or define a whole new constructor that calls TForm.Create() internally. Do not involve TForm.CreateNew() at all.
type
TAddEmployee = class(TForm)
...
public
constructor Create(AOwner: TComponent); override; // optional
constructor CreateWithDetail(AOwner: TComponent; Detail : String);
end;
constructor TAddEmployee.Create(AOwner: TComponent);
begin
CreateWithDetail(AOwner, 'Some Default Value Here');
end;
constructor TAddEmployee.CreateWithDetail(AOwner: TComponent; Detail : String);
begin
inherited Create(AOwner);
AddDetails.Caption := Detail;
end;
procedure TWelcome.SpeedButton1Click(Sender: TObject);
var
myForm : TAddEmployee;
begin
myForm := TAddEmployee.CreateWithDetail(AOwner, Details);
myForm.ShowModal;
myForm.Free;
end;

Answer 2

Declare your constructor like this:
constructor Create(AOwner: TComponent; const Detail: string); reintroduce;
Implement it like this:
constructor TAddEmployee.Create(AOwner: TComponent; const Detail: string);
begin
inherited Create(AOwner);
AddDetails.Caption := Detail;
end;
Call it like this:
myForm := TAddEmployee.Create(MainForm, Details);
I'm not sure what you want to pass as the owner. Could be the main form, could be something else.
You should also remove the global variable named AddEmployee and so force yourself to take control over instantiating the form.
I chose to name my constructor Create, and so hide the inherited constructor of that name, to force consumers of the class to supply the Details parameter in order to make an instance of the class.