Hi There,

I try to write a procedure with generic parameters, but failed:

type
  generic TArray<T> = array of T;
procedure ProcessArray(arr: TArray<T>);
begin
end;

The compiler said "Generics without specialization cannot be used..."

But if I specialize the parameter then this procedure is useless.

Any ideas?

Thanks

This is not yet supported. A proof of concept implementation exists locally on my computer however. It will then look like this:

=== code begin ===

type
   generic TArray<T> = array of T;
generic procedure ProcessArray<T>(arr: TArray<T>);
begin
end;
begin
   // usage:
   specialize ProcessArray<LongInt>(someintarray);
end.

=== code end ===

Regards,
Sven

Thanks. This is sort-of too verbose when use. I have no comments about how to define it, but when use it, can we just use:

ProcessArray(someintarray); ?

The complier should be able to "specialize" it implicitly because it knows someintarray is array of integer?

alternatively, how about this:

var
  proc_ints: specialize ProcessArray<LongInt>;
begin
  proc_ints(someintarray);
end;

use it without explicit specialize is best, however.

2013/9/4 Sven Barth

Xiangrong Fang wrote

Thanks. This is sort-of too verbose when use. I have no comments about how to define it, but when use it, can we just use: ProcessArray(someintarray); ?

No. Generics are specialized with "<SomeType>", so not using it for procedures/functions/methods as well is inconsistent.

No. In non-Delphi modes specializations require "specialize". This is for consistency of the language and also for simplification of the parser in those modes.

And just in case: The syntax is not up to debate.

Regards,
Sven

Hi Sven,

Not to "debate" the syntax, but just ask :-)

1) in my second example: proc_ints: specialize ProcessArray<LongInt>; it is "specialized". Why this is still not consistent ?

2) in delphi mode, "specialize" is not required anywhere, right? If so, can you write an example of your new proposal in delphi mode? btw, my last experience with Delphi is 6 or 7, there was no generics yet.

Thanks

2013/9/4 Sven Barth

You declared "proc_ints" as a variable and specialized a procedure. That is not correct from the typing point of view. We'd either need a new section type for procedure/function specializations or we ensure that the following works:

=== code begin ===
type
   generic TArrayProc<T> = procedure(arr: TArray<T>);
var
   proc_ints: specialize TArrayProc<LongInt> = @specialize
ProcessArray<LongInt>;
=== code end ===

2) in delphi mode, "specialize" is not required anywhere, right? If so, can you write an example of your new proposal in delphi mode? btw, my last experience with Delphi is 6 or 7, there was no generics yet.

The same just without "generic" and "specialize". This is then Delphi compatible (except the fact that Delphi does not support global generic functions/procedures, but only generic methods).

Regards,
Sven