Re: scripting/extension language for Ada (we have an opportunity here)

[blaak@infomatch.com]

In article <38A47E5A.42406034@earthlink.net>,
  "Robert I. Eachus" <rieachus@earthlink.net> wrote:
> Concept:  Build a special version of gnat for scripting purposes [...]
> Requirements:
[...]
> 2 Procedure, function, (and entry?) calls which do not match a
> subprogram or entry declared in the script will be searched for
> using a search path.

I would recommend against this one. Procedures and processes are very
different things. If nothing else, typos for an intended procedure
call should not accidentally invoke a process. By using some
lightweight invocation syntax, the distinction can be kept. Maybe even
just Run(...).

If you don't make a distinction between procedures and processes then
you will be forced to have all these rules for the conversion of
non-string parameters into process arguments, and process results back
into Ada. Preserving the distinction lets this be unnecessary by using
explicit interfaces to and from processes. The syntax should
definitely be easy to express, but the distinction should be there.

> 4) Environment variables shall be treated as String
(Unbounded_String?)
>  variables in an outer scope, and shall be > hidden by identically
>  named variables in inner scopes.  (In other > words, it must be
>  possible to pass a modified set of environment > variables to
>  nested calls.)

Again I would preserve the distinction, since environment variables
cross processes, but local variables don't. It would be a real drag if
my local variables could accidentally be propagated to subprocesses
(maybe I have one called DISPLAY).

Note also that having environment variables be directly in the
namespace of the Ada script implies that the scripting language must
be case sensitive.

I would suggest either a special package where environment variables
can be read and set or a simple get/set routine pair.


Cheers,                                        The Rhythm is around me,
                                               The Rhythm has control.
Ray Blaak                                      The Rhythm is inside me,
blaak@infomatch.com                            The Rhythm has my soul.


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