[SOLVED] Generics

[egsuh]

Hi,

Regarding generics, is there any change between fpc 3.0.0 and fpc 3.0.2?

I wrote a unit using "specialize" of TFPCObjectList  as follows:

   TCF = specialize TFPCObjectList<TMyClass>;


This compiles well on a machine with FPC 3.0.0, but makes following error on machine with FPC 3.0.0.

   codeframe.pas(55,19) Error: Identifier not found "specialize"

What would be possible reason?

Regards,

[egsuh]

I found the reason.

This works only in  {$mode objfpc}, not in {$mode delphi}.

[molly]

This works only in  {$mode objfpc}, not in {$mode delphi}.

Yes and no.

Yes, your specific declaration indeed does, but you can use generics in both modes. It just works a bit differently when declaring generics (or specialization as in your example).

If you want to know the difference then have a look in these chapters and for your case i guess read the Delphi specific parts to see how to 'specialize' a generic in Delphi mode.

[Thaddy]

basically mode delphi is a more concise syntax (drop specialize). It is my impression that the compiler people actually working on generics prefer mode delphi themselves.
Also note the mode is per unit: you can use a unit that uses objfpc generics syntax in another unit using mode delphi. It is transparent.

[egsuh]

Molly and Thaddy,

Thank you very much for your replies. I was just about to ask whether a project may be mixed with both modes, and you have already given the answer.

[PascalDragon]

It is my impression that the compiler people actually working on generics prefer mode delphi themselves.

Considering that I'm the only one that is working on generics I can definitely say that I prefer FPC's syntax, cause the Delphi one is a PITA to parse. To see what I mean, just keep in mind that the non Delphi modes allow this already while mode Delphi does not:

Code: Pascal  [Select][+][-]

1. someint := specialize SomeFunc<Integer>(SomeArg) + specialize SomeOtherFunc<Integer>(SomeOtherArg);

Mode Delphi can not yet handle such "complex" expressions, there you'd need to write this:

Code: Pascal  [Select][+][-]

1. tmp := SomeFunc<Integer>(SomeArg);
2. someint := tmp + SomeOtherFunc<Integer>(SomeOtherArg);