TITLE

with takes a context

VERSION

  Maintainer: David Nicol <perl6rfc@davidnicol.com>
  Date: 28 Sep 2000
  Mailing List: perl6-language@perl.org
  Number: 340
  Version: 1
  Status: Developing

ABSTRACT

"call frames" become useful as objects. The current one is always with with no argument and you can get into an arbitrary one by using with $whatever BLOCK in either forward or backward form, like if.

DESCRIPTION =item description by commented example

	sub A{
		my $A = shift;
		return with;
	};

	$context1 = A(3);
	print "$context1";		# something like CONTEXT(0XF0GD0G)
        print "$A" with $context1;	# prints 3
        with $context1{print "$A"};	# same thing

coexistence w/ pascal-like with

The context-access with takes a scalar argument, the pascal-like with takes a hash. If the pascal-like with is considered as describing aliases to defined variables, the two have deep similarities.

CONTEXT objects in other contexts

In an array context, one of these CONTEXT things will expand into key-value pairs if it can.

warning about memory leaks

using with to store contexts may adversely affect memory recycling.

IMPLEMENTATION

Perl5 has the hooks required to do this: the closure stuff. This proposed with keyword makes access into such things more explicit.

REFERENCES