DesignPatterns. Mediator

Объекты связаны друг с другом через посредника. Так называемая слабая связанность.

program MediatorPattern;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils,
  uMediator in 'uMediator.pas';

var
  Stas: TColleague;
  Masha: TColleague;
  chat: TMediator;

begin
  chat := TMediator.Create();
  chat.AddParticipant(TColleague.Create(1, 'Stas'));
  chat.AddParticipant(TColleague.Create(2, 'Masha'));
  Stas := chat.Colleague[0];
  Masha := chat.Colleague[1];
  try
    Stas.Send('Привет, Маша, пойдем гулять?', Masha);
    Masha.Send('Привет, Стас, конечно!', Stas);
    ReadLn;
  finally
    chat.Free();
  end;
end.

Паттерн “Медиатор”

unit uMediator;

interface

uses
  System.SysUtils, System.generics.Collections;

type
  TMediator = class;

  TColleague = class
    FId: integer;
    FName: string;
    FMediator: TMediator;
  public
    constructor Create(aId: integer; aName: string);
    destructor Destroy; override;
    procedure Send(aMsg: string; aCoallegue: TColleague);
    procedure Notify(aMsg: string; aSenderCoallegue: TColleague);
    property Id: integer read FId;
    property Name: string read FName;
    property Mediator: TMediator read FMediator write FMediator;
  end;

  TMediator = class
    FColleagues: TObjectList<TColleague>;
  private
    function GetColleague(aIndex: integer): TColleague;
  public
    constructor Create();
    destructor Destroy; override;
    procedure Send(sSenderCoallegue: TColleague; aMsg: string; aColleague: TColleague);
    procedure AddParticipant(aColleague: TColleague);
    property Colleague[aIndex: integer]: TColleague read GetColleague;
  end;

implementation

{ TMediator }

procedure TMediator.AddParticipant(aColleague: TColleague);
begin
  if aColleague <> nil then
    FColleagues.Add(aColleague);
  aColleague.Mediator := Self;
end;

constructor TMediator.Create;
begin
  FColleagues := TObjectList<TColleague>.Create(true);
end;

destructor TMediator.Destroy;
begin
  FColleagues.Free();
  inherited;
end;

function TMediator.GetColleague(aIndex: integer): TColleague;
begin
  Result := FColleagues[aIndex];
end;

procedure TMediator.Send(sSenderCoallegue: TColleague; aMsg: string; aColleague: TColleague);
var
  i: integer;
  colleague: TColleague;
begin
  for i := 0 to FColleagues.Count - 1 do
  begin
    colleague := FColleagues[i];
    if colleague.Id = FColleagues[i].Id then
    begin
      FColleagues[i].Notify(aMsg, sSenderCoallegue);
      Break;
    end;
  end;
end;

{ TColleague }

constructor TColleague.Create(aId: integer; aName: string);
begin
  FMediator := TMediator.Create();
  FId := aId;
  FName := aName;
end;

destructor TColleague.Destroy;
begin
  FMediator.Free();
  inherited;
end;

procedure TColleague.Notify(aMsg: string; aSenderCoallegue: TColleague);
begin
  WriteLn(aSenderCoallegue.Name + ': ' + aMsg);
end;

procedure TColleague.Send(aMsg: string; aCoallegue: TColleague);
begin
  FMediator.Send(Self, aMsg, aCoallegue);
end;

end.
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