How do you call a procedure given the procedure pointer in Pascal? [closed] - pascal

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Given an array of pointers where those pointers are to procedures and where they pass a single pointer passed to a procedure, how do you call the passed pointer?
procedure CallPointerProc(Proc : Pointer);
begin
// ???????????
end;
The old DOS method was fairly simple but inline is not available on Windows port so couldn't even convert to ebx,esp, etc..:
inline(
$89/$E3/ {mov bx,sp}
$36/$FF/$1F/ {call dword ptr ss:[bx]}
$83/$C4/$04); {add sp,4}

Answer 1

In general, you should not pass a blank pointer but a type that describes the exact type of subroutine like parameters with their types and return type in case of a function.
Example on how to declares procedure or function types
type
// A procedure with no parameters
TProc = procedure;
// A procedure that expexcts a string
TStringProc = procedure(str: string);
// A function that expects and returns a string
TStringToStringFunc = function(str: string): string;
A function that expects a pointer to a procedure and calls it:
procedure CallPointerProc(Proc : TProc);
begin
Proc();
end;
A function that expects a blank pointer, casts it to a procedure and then calls that:
procedure CallPointerProc(Proc : Pointer);
var
TypedProc: TProc;
begin
TypedProc := TProc(Proc);
TypedProc();
end;
Demo code that works with both definitions of CallPointerProc above. Note that we use the # symbol to get the address of a defined procedure or function.
procedure Demo;
begin
Writeln('Hello World');
end;
begin
CallPointerProc(#Demo);
Readln;
end.