pointer of function

DELPHIer,

How can I get the pointer of a function and make use of it ?

For example,
There is a Button and some other controls in Main Form and there is a Click event in the Button object .
But, I also have three other functions called, FuncA, FuncB and FuncC inside the object of the Main Form.
So, how can I jump to FuncA or FuncB or FuncC when I click the Button through their pointers ?

thanks,
Andrew
andrewyuAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

extremeCommented:
That depends on the prototype of the functions. The prototype is how the functions are declared, for example, the function for the OnClick of the Button is of type TNotifyEvent that is declared as:

TNotifyEvent = procedure (Sender : TObject) of object;

That means that TNotifyEvent is a pointer to a procedure that received a sole parameter of type TObject, and that the procedure is inside an object.

So, supposing that your functions have the same prototype (receive a sole parameter of type TObject), then you can declare in some other object three field of type TnotifyEvent. Then you can do something like this:

Form2.FuncAAddress := Form1.FuncA;
Form2.FuncBAddress := Form1.FuncB ... the same for FuncC

then you simply can call the function pointer like this:

procedure TForm2.CallFuncA;
begin
  FuncAAddress (self);
end;

that will call FuncA of the Form1 passing as parameter the self pointer. Remember that is very important to declare the function pointer with the corresponding function prototype or Delphi will refuse to compile giving you an error.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Delphi

From novice to tech pro — start learning today.