【Delphi】Utils.EventBus

unit Utils.EventBus;

interface

uses
    System.Classes;

type
    IEventBus = interface(IUnknown)
        procedure Notify(information: TObject);
    end;

////////////////////////////////////////////////////////////////////////////////

    TEventBus = class(TObject)
    private
        subscribers: TInterfaceList;
    public
        constructor Create;
        destructor Destroy; override;
        procedure Attach(subscriber: IEventBus);
        procedure Detach(subscriber: IEventBus);
        procedure Push(information: TObject);
    end;

implementation

constructor TEventBus.Create;
begin
    subscribers := TInterfaceList.Create;
end;

destructor TEventBus.Destroy;
begin
    subscribers.Free;
    subscribers := nil;
    inherited Destroy;
end;

procedure TEventBus.Attach(subscriber: IEventBus);
begin
    subscribers.Lock;
    try
        if subscribers.IndexOf(subscriber) < 0 then begin
            subscribers.Add(subscriber);
        end; 
    finally
        subscribers.Unlock;
    end;
end;

procedure TEventBus.Detach(subscriber: IEventBus);
begin
    subscribers.Lock;
    try
        if subscribers.IndexOf(subscriber) > -1 then begin
            subscribers.Remove(subscriber);
        end; 
    finally
        subscribers.Unlock;
    end;
end;

procedure TEventBus.Push(information: TObject);
var
    i: Integer;
begin
    subscribers.Lock;
    try
        for i := 0 to subscribers.Count - 1 do begin
            IEventBus(subscribers.Items[i]).Notify(information);
        end;            
    finally
        subscribers.Unlock;
    end;
end;

end.