Re: Access to classwide type

[Laurent Guerby <guerby@acm.org>]

dvdeug@x8b4e53cd.dhcp.okstate.edu (David Starner) writes:
> [...] I believe GNAT just implements it as a small wrapper around 
> C's free function.

For the default allocation pool in GNAT yes (gnat_free). 

In general at the language level, if you write your own pools, the
deallocation function (see System.Storage_Pools) has size and
alignment parameters, and the compiler has always a way to fill them
with the corresponding allocated parameters as required by 13.11.2
(9). So you know a bit more than C free.

I believe that for all tagged types, GNAT generates a few hidden
primitive subprograms to handle this in the class-wide case (see -gnatdg
expansion of 'size attributes on such beasts to make your mind ;-). I
don't know for other compiler technology.

For arrays and discriminated types, the compiler can obviously
generate small pieces of code to compute the size of things, since the
information must be around in some ways to do all the Ada required
checking.

-- 
Laurent Guerby <guerby@acm.org>