Re: Generics - Difference between ADA and Modula--3

[dvdeug@x8b4e53cd.dhcp.okstate.edu (David Starner)]

On 5 Feb 2001 20:51:30 GMT, Mark Carroll <carroll@cis.ohio-state.edu> wrote:
>In article <95eumd$8i41@news.cis.okstate.edu>,
>David Starner <dstarner98@aasaa.ofe.org> wrote:
>
>>Ada is designed so that it is possible to garbage-collect it. It's
>>only garbage-collected on the JVM's, which don't give you any control.
>>If there was another GC implementation, any garbage-collection control
>>would be implementation-specific.
>
>That's a pity. So, there aren't any Ada compilers that compile to
>native code and offer a runtime with decent GC? 

Not that I've heard of. I hacked the Boehm-Weiser GC into GNAT's runtime,
but GNAT uses some funky virtual base system that makes it crash when
running under a garbage collector. I may find the time to do it properly
(multilib it, in GCC terms), but at the very least that's going to wait
until a version of GNAT depending on the GCC 3.0 build technology comes
out.

>Are there any other
>special tricks used to make memory management easier than, say, a C
>programmer might expect?

Ada's fairly flexible about stack usage. Occasionally you'll see something
like 

for I in 1 .. 50 loop
	declare
		A: array (0 .. I) of Integer;
	begin
		...
	end;
end loop;

where there's a varying array. Or alternately:

type bob is array (integer range <>) of foo;
...
while (complex_condition) loop
	declare
		Token: bob := Something_Returning_A_Varying_String;
	begin
		...
	end;
end loop;

where you return a varying array. It doesn't catch a lot of stuff that 
really needs garbage collection, but it catches some of the places where
a C program might leak memory.

-- 
David Starner - dstarner98@aasaa.ofe.org
Pointless website: http://dvdeug.dhis.org
"I don't care if Bill personally has my name and reads my email and 
laughs at me. In fact, I'd be rather honored." - Joseph_Greg