Re: Ada.Command_Line.Argument_Count question

[Keith Thompson <kst-u@mib.org>]

Gautier write-only <gautier_niouzes@hotmail.com> writes:
> On 15 sep, 22:58, Thomas Løcke wrote:
>> The RM has this to say about Argument_Count:
>> "If the external execution environment supports passing arguments to a
>> program, then Argument_Count returns the number of arguments passed to
>> the program invoking the function. Otherwise it returns 0. The meaning
>> of “number of arguments” is implementation defined."
>>
>> I'm wondering what that last sentence mean? Is the RM trying to tell me
>> that Argument_Count cannot be trusted to yield the same result on
>> different systems (Unix, BSD, Windows, Linux and so on)?
>
> Perhaps... And it the behaviour is compiler-dependent too!
> Some systems will give 2 for ["a b" c]; others, 3 (maybe only DOS on
> that!).
> Some compilers will always return [*.adb] as is, others (GNAT) will
> return one argument for each file corresponding to that pattern, or
> still "*.adb" if there is no such file!
[...]

The behavior you describe has nothing to do with the compiler, at
least not on Unix-like systems.  If you type
    ./my_program *.adb
in a Unix shell, my_program will see a list of file names; it will
have no way to know that the list is the result of expanding a
wildcard expression.  All the processing happens in the shell.  And of
course programs can be invoked by other programs, not just by the
shell.

On other systems, though, the Ada.Command_Line implementation might
(optionally?) do some additional processing.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
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