Hi all,

FPC uses 2 keywords for generics: "generic" for generic definition block, and "specialize" for generic type implementation. I think the "generic" keyword is quite redundant, useless, and too verbose since generics already use pair of to define a generics type. Generics definition should be enough described using the pair of only without "generic" keyword.

The example below should be very obvious to the compiler:

(*** begin of example ***)
type
   TRegularIntegerArray: array[0..100] of integer;
   TGenericArray<T>: array[0..100] of T;
var
   IntegerArrayFromGeneric = specialize TGenericArray<integer>;
(*** end of example ***)

Or, if we MUST use "generic" keyword to help compiler parse the code, also make the syntax less cryptic, I suggest using the example below:

(*** begin of example ***)
type
   TList = generic class(TObject)
     type public
        TCompareFunc = function(const Item1, Item2: T): Integer;
     var public
       data : T;
     procedure Add(item: T);
     procedure Sort(compare: TCompareFunc);
   end of T;
   TGenericArray: generic array[0..100] of T;
var
   PointerListFromGeneric = specialize TList for Pointer;
   IntegerArrayFromGeneric = specialize TGenericArray for Integer;
(*** end of example ***)

Though I agree that a generic MUST have a clear structure definition (in type section) before it's being used (in var section), since generic is all about type definition, also for ease of readability.

Any comments?

-Bee-

has Bee.ography at:
http://beeography.wordpress.com

Bisma Jayadi wrote

FPC uses 2 keywords for generics: "generic" for generic definition block, and "specialize" for generic type implementation. I think the "generic" keyword is quite redundant

I think it is useful, because it allows future language extensions to also use the syntax without conflicting with generics (e.g., the Objective Pascal draft syntax also makes use of angle brackets for a couple of things).

Jonas

Yes, I know, the ':' and '=' usage is wrong, it's a mistypo. :-D

Anyway, using my suggested generic syntax(es), it's allowed to specialize a generic type in type section. Like below example:

Or:

-Bee-

has Bee.ography at:
http://beeography.wordpress.com

Hi all, Any comments?

We tried to do it keeping the spirit of pascal in mind. The array in an
array declaration is also useless, you could do
type
  a : integer[0..100];

Using generic is verbose but imo one defines seldomly generic types so it is ok because it improves readability of the construct.

I think it is useful, because it allows future language extensions to also use the syntax without conflicting with generics (e.g., the Objective Pascal draft syntax also makes use of angle brackets for a couple of things).

Then my second syntax proposal might overcome possible conflict with future or other symbol implementation, since it uses no symbol at all, and IMO more pascalish (less cryptic). :-D

In short, my second syntax proposal is:

- generic definition syntax (type section):
   {type_name} = generic {type_definition} of {generic_holder} ;
- generic implementation syntax (var section):
   {var_name} : specialize {generic_type} for {implemented_type} ;
   or if it's defined in type section:
   {type_name} = specialize {generic_type} for {implemented_type} ;

-Bee-

has Bee.ography at:
http://beeography.wordpress.com

Where is the name of the type parameters given? Well and we used < ... > because a lot of programmers recognize it as generic/template definition.