Re: Ada standard and maximum line lengths

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 13-01-29 17:29 , Georg Bauhaus wrote:
> On 29.01.13 13:31, Niklas Holsti wrote:
>> Even for hypothetical SW of some sort that generates Ada source code
>> automatically, I think it very unlikely that it would generate
>> identifiers of that length, since Ada identifiers can be qualified and
>> sorted into packages etc. much more flexibly than is the case for linker
>> symbols.
> 
> GNAT writes similar identifiers into object files, and
> the same hysterical raisins spoil the cake. At least the
> names---those to be exported to other compilers---seem shorter
> if package hierarchies are not used extensively.

So what? These are *linker symbols*, not Ada (source) identifiers. I
don't understand why you bring them into a discussion of source-code
identifier lengths.

In many cases, for example for the C++ symbol that you gave, the symbols
are not even lexically legal Ada identifiers.

> Alas, the problem of exceedingly long names in object files
> can be worked around by allowing lengthy identifiers in source
> text.

Incomprehensible. Is there a "not" missing somewhere in that sentence?

While long linker symbols are ugly, and a poor work-around for linker
weaknesses, they are troublesome only for people who deal with low-level
debugging, or other tools on that level.

> There is a better alternative. It needs to address the
> issue at some object interchange level, which is typed.
> Something between function libraries from around 1970 and
> {.NET, JVM, Corba, Zero-C Ice, ...}.

Certainly the linker principles and operations could stand improvement
and modernisation. Not to speak of the unspeakably (as I said :-)) poor
documentation of symbolic information emitted by compilers and stored in
"standard" forms like DWARF (which is still vastly better than the older
standards for debug info).

> An incentive is needed that creates fruitful cooperation of
> languages, if that is where long identifiers are a pain, and
> a source of cumbersome, costly configuration.

As I've understood it, the GNAT Ada/C++ linkage does *not* involve
typing those long, mangled linker symbols into an Ada program as
identifiers. GNAT understands the GNU C++ compiler well enough to hide them.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
      .      @       .