RFC 40 (v1) Module Scope Control

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=head1 TITLE

Module Scope Control

=head1 VERSION

    Maintainer: Bryan C. Warnock <[EMAIL PROTECTED]>
    Date: 5 Aug 2000
    Version: 1
    Mailing List: [EMAIL PROTECTED]
    Number: 40

=head1 ABSTRACT

Modules should be able to, internally, control how they (and their
members) are scoped.

=head1 DESCRIPTION

Hooks should allowed so that module writers can control global and lexical
scoping of its own subs and variables.


    package MyModule;
    @globals = qw/$foo $bar %hash @array/;
    @lexicals = qw/$ork $gork @hork $./;
    BEGIN{$. = 834;}
    
    #!/usr/local/bin/perl    
    use MyModule;  # same as use MyModule; local $ork; local $.=834;
    use OtherPackage;
    
    print $MyModule::foo;  # Okay, it exists
    foo() if ($MyModule::$ork);   # Okay, it's scoped here.
    OtherPackage::bar();
    print $.;   # Prints 834.
    

    package OtherPackage;
    sub bar {
        print $MyModule::$bar;  # Okay, global.
        print $MyModule::$hork[0];   # Nope, not seen down here.    
        print $.;  Prints whatever it was before 834.  0?
    }


(This is not to suggest that this be the syntax.)


=head1 MOTIVATORS

Impatience, and a little laziness.

=head1 IMPLEMENTATION

I'm not too terribly sure I even got the terminology correct.  Scoping
makes my head hurt.  :-(

I'll concede right now, the above is a mess, and I'd like to find a more
elegant way of handling this.

The point is to allow a module to define (or override) variables only in
the file where C<use $Module;> was invoked.

I thought there was something in Perl 5 that made this easier from a core
perspective, but it seemed to be overly complex for my puny little brain.

This should allow modules to behave like pragmas, in some respects.

=head2 SUMMARY OF IMPLEMENTATION

I've no real concrete ideas on this, sorry.

=head2 IMPACT

=over 4

=item *

Impact on Perl 5.  Mutual compatibility between Perl 5 and Perl 6, with the
exception of this feature and the sematics it would add.  (Obviously, 
other changes to the language notwithstanding.)

=back

=head1 REFERENCES

    RFC 2 (which could then be written as a module), and a forthcoming
RFC on the Shell pragma.  (Which could also then be written as a
module.)