Question

I am using Delphi 7 and trying to create Delphi application having 5 buttons on Main Form. Each button click will display another form with some components on it. The most components on subform for all button clicks are same. Which will be better way to do:

1. to create new form on each click and and destroy it when it closed

   or

2. to create one form once and use the same form for others (using directly ShowModal)?

But the problem in 2nd option is when I show that subform on 2nd time then the values of form remains same as when entered first time. Any solution to refresh it quickly?? or any other solution to display form?

Answer 1

The problem is that these forms are already auto-created when you add them to your app. You only need to create one of these, and remove its auto-creation.

Go to Project > Options > Forms tab and look at the list of ‘Auto-Create forms’. Remove your sub-form from this list (adding it to the list on the right of ‘available forms’).

Now you don’t need to create 5 different forms if you are showing them as modal, especially. You just need one…

Unit1

5 TButton controls, all sharing the same ButtonClick event (for this example) and whatever other controls you wish…

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Button5: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses
  Unit2;

procedure TForm1.ButtonClick(Sender: TObject);
var
  F: TForm2; //Declaration of the form
begin
  F:= TForm2.Create(nil); //Creation of the form
  try
    F.ShowModal;
  finally
    F.Free; //Destruction of the form
  end;
end;

end.

Note that I never once refer to the name Form2. Instead, I temporarily declare F: TForm2 just for the duration that I need it. If it wasn’t going to be modal, you would need a far different approach.