How to Pass Functions as Parameters in Procedures in Delphi?

Question

Is it possible to pass an object function as a parameter in a procedure rather than passing the whole object?

I have a record definition with a function defined as a public class parameter such as:

    TMyRecord = record
      public
        class function New(const a, b: Integer): TMyRecord; static;
        function GiveMeAValue(inputValue: integer): Single;
      public
        a, b: Integer;
      end;

The function could be something like:

    function TMyRecord.GiveMeAValue(inputValue: Integer): Single;
    begin
      RESULT := inputValue/(self.a + self.b);
    end;

I then wish to define a procedure that calls on the class function GiveMeAValue but I don't want to pass it the whole record. Can I do something like this, for example:

    Procedure DoSomething(var1: Single; var2, var3: Integer, ?TMyRecord.GiveMeAValue?);
    begin
      var1 = ?TMyRecord.GiveMeAValue?(var2 + var3);
      //Do Some Other Stuff
    end;

If so then how would I correctly pass the function as a procedure parameter?

Answer 1

You can define a new type for the function like

TGiveMeAValue= function(inputValue: integer): Single of object;// this definition works fine for methods for records.

then define the method DoSomething

Procedure DoSomething(var1: Single; var2, var3: Integer;GiveMeAValue: TGiveMeAValue);
begin
  writeln(GiveMeAValue(var2 + var3));
end;

And use like so

var
  L : TMyRecord;
begin
    l.a:=4;
    l.b:=1;
    DoSomething(1, 20, 5, L.GiveMeAValue);
end;