Multicast event

DFM:

object Form15: TForm15
  Left = 0
  Top = 0
  Caption = 'Form15'
  ClientHeight = 187
  ClientWidth = 605
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  OnDestroy = FormDestroy
  PixelsPerInch = 96
  TextHeight = 13
  object Memo1: TMemo
    Left = 8
    Top = 8
    Width = 185
    Height = 89
    Lines.Strings = (
      'Memo1')
    TabOrder = 0
  end
  object Memo2: TMemo
    Left = 208
    Top = 8
    Width = 185
    Height = 89
    Lines.Strings = (
      'Memo2')
    TabOrder = 1
  end
  object Memo3: TMemo
    Left = 408
    Top = 8
    Width = 185
    Height = 89
    Lines.Strings = (
      'Memo3')
    TabOrder = 2
  end
  object Edit1: TEdit
    Left = 304
    Top = 128
    Width = 121
    Height = 21
    TabOrder = 3
    Text = 'Edit1'
  end
  object Button1: TButton
    Left = 184
    Top = 126
    Width = 99
    Height = 25
    Caption = 'Send meeesage'
    TabOrder = 4
    OnClick = Button1Click
  end
end

Unit

unit MainU;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs,

  System.MulticastEventU, Vcl.StdCtrls;

{$M+,O+}
{$IFOPT O-}
{$MESSAGE Fatal 'Optimization _must_ be turned on for this unit to work!'}
{$ENDIF}


type
  TForm15 = class(TForm)
    Memo1: TMemo;
    Memo2: TMemo;
    Memo3: TMemo;
    Edit1: TEdit;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    FMulticastEvent: TMulticastEvent<TGetStrProc>;
    procedure StrProc1(const message : string);
    procedure StrProc2(const message : string);
    procedure StrProc3(const message : string);
  end;

var
  Form15: TForm15;

implementation

{$R *.dfm}

procedure TForm15.Button1Click(Sender: TObject);
begin
  FMulticastEvent.Invoke(Edit1.Text);
end;

procedure TForm15.FormCreate(Sender: TObject);
begin
  FMulticastEvent := TMulticastEvent<TGetStrProc>.Create;
  FMulticastEvent.Add(StrProc1);
  FMulticastEvent.Add(StrProc2);
  FMulticastEvent.Add(StrProc3);
end;

procedure TForm15.FormDestroy(Sender: TObject);
begin
  FMulticastEvent.Free;
end;

procedure TForm15.StrProc1(const message: string);
begin
  Memo1.Lines.Add(message);
end;

procedure TForm15.StrProc2(const message: string);
begin
  Memo2.Lines.Add(message);
end;

procedure TForm15.StrProc3(const message: string);
begin
  Memo3.Lines.Add(message);
end;

end.