Err... because at the time, T is not yet known. It would still fail to compile even if you don't do any specialization. I guess the compiler does type checking while parsing the generic class (and its methods) declaration, not while specializing (well... it would still do type checking when specializing, but the error would be a little cryptic due to missing exact error location).
IMHO a solution would be to have additional compile-time syntax to check the type of T (but this may cause a lot of headache due to inheritance concept). Since it's impossible with the current state, the current solution would be to declare a procedural type (with T as argument) inside the generic class and instead of calling blah directly make it a procedural variable of that type as argument of Test (since it's a class function). The caveat is of course you have to pass Blah all the time. But unfortunately... it doesn't work as well :( Here's your modified program (compiled, but just run and see its output): {$mode delphi} uses SysUtils; function Blah(const val: Integer): string; inline; overload; begin Result:= IntToStr(val + 1); end; function Blah(const val: string): string; inline; overload; begin Result:= val + '1'; end; type TTestGen<T> = class type TBlah = function (const val: T): string; public constructor Create(); class function Test(val: T; ABlah: TBlah): string; inline; end; { TTestGen } constructor TTestGen<T>.Create(); begin end; class function TTestGen<T>.Test(val: T; ABlah: TBlah): string; begin Result:= ABlah(val); end; type TTestInt = TTestGen<Integer>; TTestString = TTestGen<String>; begin WriteLn(TTestInt.Test(1,@Blah)); WriteLn(TTestString.Test('test',@Blah)); end. If I don't overload Blah and pass the correct function for each call, then the result is correct. Somebody's gotta file a bug report. -- View this message in context: http://free-pascal-general.1045716.n5.nabble.com/generics-question-tp4389896p4395332.html Sent from the Free Pascal - General mailing list archive at Nabble.com. _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal