Re: Wide Character Problem in Ada.Numerics

[Adam Beneschan <adam@irvine.com>]

On Apr 25, 5:27 pm, Brian May <b...@snoopy.apana.org.au> wrote:
> >>>>> "Jean-Pierre" == Jean-Pierre Rosen <r...@adalog.fr> writes:
>
>     >> Wait a minute... are you saying that in GNAT, you cannot WITH a
>     >> package unless the source of the WITH'ed package uses the same
>     >> encoding as the source of the package doing the WITH'ing?
>     >> Ouch.  This somehow seems to run counter to the whole
>     >> philosophy of abstraction that packages are supposed to
>     >> provide.
>
> How do you expect the compiler to know what encoding is used for each
> source file? I think it could only know if the file was compiled
> first.

Well, the original example had a problem with a language-defined
package that was WITH'ed.  So surely that file must have been compiled
first?  By *somebody*???  I hope they're not releasing runtime
packages that they've never compiled!!!!!!

But in a more general case, the compiler, when it does compile a unit
that contains characters not in the 7-bit ASCII range, probably ought
to be generating some sort of information indicating what the source
encoding was, so that it would know how to reread the source when it's
WITH'ed.  (And, in particular, whatever file contains that information
for Ada.Numerics would be part of the GNAT release.)  And in a case
where you want to WITH a unit without compiling it first (although I
don't really understand why), it should be trivial to provide some
mechanism to generate that information without compiling.

In any case, this is not a difficult problem to solve.  And IMHO a
solution is necessary, if the alternative is to require that every
source in your environment, including sources delivered as part of the
runtime and sources that you might have downloaded from Sourceforge or
somewhere else on the web, use the same source encoding.  (Actually,
that might not even be bad if they all used UTF-8.  But requiring that
every source use some nonstandard encoding method---well, yuck.)

                                         -- Adam