[FWP] namespace problem (fwd)

[Jeff Pinyan <jeffp@crusoe.net>]

Fun With Packages!

---------- Forwarded message ----------
Date: Tue, 6 Jun 2000 22:38:45 -0400 (EDT)
From: Jeff Pinyan <jeffp@crusoe.net>
Reply-To: japhy@pobox.com
To: Charles Huff <...>
Subject: Re: namespace problem

On Jun 6, Charles Huff said:

>file #1
>--------
>$gFoo = "2";
>
><call file#2 somehow>
>print $gBar;	# should output 8

>File#2
>-----------
>...
>print $gFoo;	# should output 2
>$gBar = 8;

And File#2 has a different namespace, right?  Well, I think I've solved
your problem. :)

  ### other.pl
  package Outside;
  $VAR = 100;
  sub foo {
    print $VAR;
    $VAR *= 2;
  }

  ### main.pl
  $VAR = 300;
  require "other.pl";
  Outside::foo();  # prints 100, sets $Outside::VAR to 200  
  {
    my @keys = keys %Outside::;
    my @values = values %Outside::;
    @Outside::{@keys} = @main::{@keys};
    Outside::foo();  # prints 300, sets $main::VAR to 600
    @Outisde::{@keys} = @values;
  }

This assumes, though, that you want to call a FUNCTION in other.pl -- if
you want to RUN the entire file "other.pl", but disregard the fact that
it's in another package...

  ### other.pl
  package Outside;
  print $VAR;
  $VAR *= 2;

  ### main.pl
  $VAR = 300;
  {
    my @to_copy = grep !/^main::/, keys %main::;
    @Outside::{@to_copy} = @main::{@to_copy};
    require "other.pl";  # prints $main::VAR, and makes it 600
    @main::{@to_copy} = @Outside::{@to_copy};
  }
  print $VAR;  # 600

Of course, if other.pl ISN'T in its own separate namespace, there is
nothing to deal with at all, really.  Just require() the file, and the
variables will be dealt with normally.

By the way, the code I've given you is the result of an hour's work.  Be
glad I did it. ;)

-- 
Jeff "japhy" Pinyan     japhy@pobox.com     http://www.pobox.com/~japhy/
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