[fpc-devel] Packages, Generics

Florian Klaempfl florian at freepascal.org
Mon Sep 13 13:22:07 CEST 2010

Am 13.09.2010 12:31, schrieb Willibald Krenn:
>>> OTOH 'specialize' is an additional (unfamiliar) keyword and has
>>> semantics totally unknown to the world. So why not take what's
>>> already in the language?
>> As I said, to emphasis that a new type is created, generic 
>> specialization is something really new to the language. The meaning
>> of type ... = type ...; is imo very unclear.
> Well, it's the Delphi way of creating a new type rather than an
> alias.

Since they are still assignment compatible, I don't consider it as a
really new type.

>>> FPC's generics are, however, very different to all other 
>>> implementations of generics that I know of. And I really(!)
>>> hope, that FPC does not do the C++ like duck-typing, which could
>>> give
>> FPC works in this regard as C++ which is not nice but much more
>> flexible being not only some type cast wrapper generator as in C#
>> etc.
> Well, you know my opinion. This is type-unsafe, 

It is perfectly type safe.

> C-style, poor-man's

I consider C# style generics as poor man's generics :)

> generics. 

Well, I consider them more powerful than others because the C#
programming style (having only one core implementation) can be done also
with C++ style templates, see e.g. the fgl unit of fpc.

> You are asking for trouble by following that route.

Nothing is trouble free ;)

> And one last time - C#/.NET generics are not only some 'type cast
> wrapper': think about working static fields, co-/contravariance ... .

Yes. But the principle remains the same.

> Java generics, however, could be described as type cast wrapper
> generators. And everybody on earth knows that Java generics are
> broken.
>> Let us know if you've something working and regarding the branch:
>> just tell me if you need one.
> Ok, thanks!
> Willi

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