Linking a procedure to an object for remote execution

[WILL]

Hey guys... I'm working on a tiny gui unit for use in my game projects. One of the things I'd like it to do is associate external procedures and execute them if assigned for say a button click.

Assigning them would be as simple as

[pascal]MainMenu.Button1.OnClick := YourProcedure;[/pascal]

YourProcedure() would be created by the user of the library. And Button1 would be a control object that resides inside the window object (MainMenu).

[pascal]procedure YourProcedure;
begin
// whatever
end;[/pascal]

my code to detect mouse clicks on the button object would run the 'linked' procedure from it's own code. How can I do this? Can I simply use pointers?

[JSoftware]

It's pretty easy in FreePascal. I don't know how you would do it in Delphi though..

FPC:
[pascal]procedure YourProcedure; [public, alias: 'YourProcedure'];
begin
//Do something. This procedure is in no way visible to the procedure using it
end;[/pascal]

[pascal]//In your code
procedure YourProcedureDecl; external name 'YourProcedure';

...
begin
MainMenu.Button1.OnClick := @YourProcedure;
end;[/pascal]

Is this what you were asking?

[WILL]

Hmm... not sure. Have you ever used JEDI-SDL's audio mixer?

You pass a procedure to this external procedure

[pascal]procedure Mix_HookMusicFinished( music_finished : Pointer );[/pascal]

and whatever procedure you passed to music_finished will automatically execute when the song ends. all I have to do is add this line of code for my own written procedure.

[pascal]Mix_HookMusicFinished(@RestartMusic);[/pascal]

RestartMusic is a procedure of my own making.

[Brainer]

I once tried this:
[pascal]
type
TMyEvent = procedure;

// In DLL
procedure MyDLLFuncIdle(IdleFunc: TMyEvent);
begin
FIdleFunc := IdleFunc;
end;

// In External App
procedure MyDLLFuncIdle(IdleFunc: TMyEvent); external 'MyDLL.dll';

procedure xxxIdleFunc;
begin
// do some shizzle here
end;

begin
MyDLLFuncIdle(xxxIdleFunc);
end;
[/pascal]

And it worked fine for me.

[WILL]

Hmm... well what is FIdleFunc though?

I've just found something on Delphi's ExecMethod but nothing seems to exist like it for FPC. :?

Something like ExecProcedure(Func: pointer); would be great. :lol:

[User137]

Events in normal TButton etc are very simple.

[pascal]type
TNotifyEvent = procedure(Sender: TObject) of object;

// .. and then it is put as a variable
FOnClick: TNotifyEvent;
// .. and as a property if want to make a component event of it
property OnClick: TNotifyEvent read FOnClick write FOnClick;
[/pascal]

TNotifyEvent = procedure(Sender: TObject) of object;
Here " of object" tells that the procedure must be class procedure, not a standalone procedure. Those are defined like:
TNotifyEventLonely = procedure(Sender: TObject);

You can manually make a procedure and very easily set it (as long as the parameters match the defined type):
FOnClick:=YourClickProcedure;

And in your class you can then call it like
if assigned(FOnClick) then FOnClick(self)

[Brainer]

Hmm... well what is FIdleFunc though?

Let's assume you have a procedure inside your DLL, that does certain things with the variable FIdleFunc.

A little example
[pascal]
// -- GLOBAL --
type
TMyMathEvent = procedure(Z: Single);

// -- DLL --
var
FMathFunc: TMyEvent;


procedure DLLDoIt;
var
x: Single;
begin
x := 3.14;

if Assigned(FMathFunc) then
FMathFunc(X);
end;

procedure AssignMathFunc(TheMathFunc: TMyMathEvent);
begin
FMathFunc := TheMathFunc;
end;

// -- EXTERNAL APP --
procedure AssignMathFunc(TheMathFunc: TMyMathEvent); external 'MathDLL.dll';

const
Radius = 3.225;

var
TheArea: Single;

procedure CalculateCircleArea(Z: Single);
begin
TheArea := Z * (Radius * Radius);
end;

begin
AssignMathFunc(CalculateCircleArea);
end;
[/pascal]

[JSoftware]

Will, could you try to explain a little better what you want to do?

There's a difference between calling methods and calling normal functions/procedures.

If you want to handle non-object procedures/functions you simply pass either a pointer or a type of procedure/function:

[pascal]
type
TProcedure = procedure; //Already declared in system

..
procedure SomethingLength(callBack: TProcedure);
begin
...
Callback; //Calls callback
...
end;[/pascal]

If you have a pointer you would like to call you simply typecast it to TProcedure and call it

[pascal]
TProcedure(funcPointer);
[/pascal]

As long as you are using fastcall or stdcall you are safe using this approach

[De-Panther]

I think he wants to set procedures for events of objects he create during the runtime of his game/program

like:
[pascal]
objname:=TLabel.Create(self);
objname.SetOnClick:=Procedurename;
[/pascal]

I don't think this would work(I know it won't work).
but I think that this is what he wants

[De-Panther]

I think he wants to set procedures for events of objects he create during the runtime of his game/program

like:
[pascal]
objname:=TLabel.Create(self);
objname.SetOnClick:=Procedurename;
[/pascal]

I don't think this would work(I know it won't work).
but I think that this is what he wants