Re: Thick vs. Thin bindings

[Martin Krischik <martin@krischik.com>]

Jeff Houck wrote:

> As I continue to evaluate Ada in the role of a gamephilosophyge, I've
> run across references to "thick" and "thin" bindings and I'm a bit
> confused.
> My initial design goals are to keep the number of external dependancies
> to a minimum with most of the support code written in Ada. I would like
> the code interfaces to be as simple as possible to implement for a
> designer. I believe this would necessitate a "thick" binding. Is that
> correct? Would anyone like to elaborate on the pros and cons of these
> two binding methodologies? Further reading material? Tutorials? Thx!

A thin binding just translates the C calls into Ada calls but the C'ish
philosophy is still visible. One examle of C'ish philosophy is the '\0' at
the end of strings.

Example for a thin binding to memset:

   procedure memset (
      S : in Interfaces.C.void_ptr;
      C : in Interfaces.C.int;
      N : in Interfaces.C.size_t);

   pragma Import (
      Convention    => C,
      Entity        => memset,
      External_Name => "memset");

A think binding translates the philosophy of the original language to Ada as
well.

A think binding to memset could be a generic procedure (template in C++
talk):

generic
   type A_Type    is private;
   type A_Access is access all A_Type;
procedure Mem_Set    
      Value : in A_Access ;
      Fill : in Short_Short_Integer);

I usualy suggest to build a think binding on top of a thin bindung.

With Regards

Martin

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