Hello.

The following program does not compile, because overloaded AddItem(s: string) method in ancestor is not visible from child class. Is it normal?

program Test;
{$MODE OBJFPC}
type
   TBase = class
   public
     procedure AddItem(s: string; i: integer); virtual;
     procedure AddItem(s: string);
   end;
   TDesc = class(TBase)
   public
     procedure AddItem(s: string; i: integer); override;
   end;
procedure TDesc.AddItem(s: string; i: integer);
begin
   writeln('TDesc(s,a) ', s, ' ', i);
end;
procedure TBase.AddItem(s: string; i: integer);
begin
   writeln('TBase(s,a) ', s, ' ', i);
end;
procedure TBase.AddItem(s: string);
begin
   AddItem(s, 123);
end;
var
   lBase: TBase;
   lDesc: TDesc;
begin
   lBase := TBase.Create;
   lDesc := TDesc.Create;
   lBase.AddItem('test'); // OK
   lDesc.AddItem('test'); // Error: Wrong number of parameters specified
for call to "AddItem"
   readln;
end.

On Fri, Feb 7, 2025 at 2:40 PM Maxim Ganetsky via fpc-devel wrote:

It compiles if you declare the methods in TBase as "overload". D7 refuses to compile this code (even with "overload"), but D7 is a little bit old...

D7 refuses to compile this code (even with "overload"), but D7 is a little bit old...

Well, Delphi is a bit picky about the order: it must be "overload; virual;" (I had "virual; overload;")
So, with that fixed, D7 compiles the code as well.

From documentation:

If the overload keyword is not present, then all overloaded versions must reside in the same unit, and if it concerns methods part of a class, they must be in the same class, i. e. the compiler will not look for overloaded methods in parent classes if the overload keyword was not specified.

https://www.freepascal.org/docs-html/ref/refse96.html

Regards, Michał.

W dniu 2025-02-07 o 14:23, Maxim Ganetsky via fpc-devel pisze:

07.02.2025 22:27, Michał Gawrycki пишет:

Thanks, guys.