Project: PROCTYPE.DPR

Project Structure

• PROCTYPE.DPR
• PROCFORM.PAS
• PROCFORM.DFM

program Proctype;

uses
  Forms,
  ProcForm in 'ProcForm.pas' {Form1};

{$R *.RES}

begin
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.

unit ProcForm;

interface

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

type
  {procedure type definition}
  IntProc = procedure (var Num: Integer);

  TForm1 = class(TForm)
    ApplyButton: TButton;
    DoubleRadioButton: TRadioButton;
    TripleRadioButton: TRadioButton;
    procedure FormCreate(Sender: TObject);
    procedure ApplyButtonClick(Sender: TObject);
    procedure DoubleRadioButtonClick(Sender: TObject);
    procedure TripleRadioButtonClick(Sender: TObject);
  private
    { Private declarations }
    IP: IntProc;
    X: Integer;
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

{procedures of the IntProc type}
procedure DoubleTheValue (var Value: Integer);
begin
  Value := Value * 2;
  ShowMessage ('Value doubled: ' + IntToStr (Value));
end;

procedure TripleTheValue (var Value: Integer);
begin
  Value := Value * 3;
  ShowMessage ('Value tripled: ' + IntToStr (Value));
end;

{initialization code}
procedure TForm1.FormCreate(Sender: TObject);
begin
  IP := DoubleTheValue;
  X := 2;
end;

{push button OnClick event}
procedure TForm1.ApplyButtonClick(Sender: TObject);
begin
  IP (X);
end;

{Radio buttons OnClick events}
procedure TForm1.DoubleRadioButtonClick(Sender: TObject);
begin
  IP := DoubleTheValue;
end;

procedure TForm1.TripleRadioButtonClick(Sender: TObject);
begin
  IP := TripleTheValue;
end;

end.

object Form1: TForm1
  Left = 201
  Top = 141
  Width = 305
  Height = 179
  ActiveControl = ApplyButton
  Caption = 'Proc Type'
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'MS Sans Serif'
  Font.Style = []
  OnCreate = FormCreate
  PixelsPerInch = 96
  TextHeight = 13
  object ApplyButton: TButton
    Left = 168
    Top = 56
    Width = 89
    Height = 41
    Caption = 'Apply'
    TabOrder = 0
    OnClick = ApplyButtonClick
  end
  object DoubleRadioButton: TRadioButton
    Left = 40
    Top = 40
    Width = 81
    Height = 33
    Caption = 'Double'
    Checked = True
    TabOrder = 1
    TabStop = True
    OnClick = DoubleRadioButtonClick
  end
  object TripleRadioButton: TRadioButton
    Left = 40
    Top = 88
    Width = 81
    Height = 25
    Caption = 'Triple'
    TabOrder = 2
    OnClick = TripleRadioButtonClick
  end
end