Re: thick? thin? binding

[Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>]

Immanuel Scholz <news@kutzsche.net> writes:

> Hi,
> 
> I read through 1 and a half Ada book and still doesnt catch what "thick" or 
> "thin" binding mean... 

It's not really an Ada concept; it's a general concept.

> I know "flat" binding from C or "name mangling" from C++. It this
> related to this?

No.

Let me give an example. Microsoft Windows has a large API, called
Win32. There is a "thin" binding to this, called Win32Ada.

The thin binding directly imports the C functions. So whereever the C
function uses a pointer, you get a parameter of type System.Address.
Wherever the C function uses a string, it must be null-terminated.

A "Thick binding" to Win32 would use either Ada access types or just
"in out" parameters, instead of System.Address. It would also use Ada
String instead of null-terminated strings. Typically, this requires
intermediate code to convert between the too. The amount of this
intermediate code determines the "thickness" of the binding.

An even thicker binding (like Windex,
http://users.erols.com/leakstan/Stephe/Ada/windex.html) goes beyond
that. It replaces the "window message handlers" of the Win32 API with
dispatching on Window_Type objects.

Hope this helps.
-- 
-- Stephe