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=head1 TITLE
Generalize =~ to a special-purpose assignment operator
=head1 VERSION
Maintainer: Nathan Wiger <[EMAIL PROTECTED]>
Date: 29 Aug 2000
Mailing List: [EMAIL PROTECTED]
Version: 1
Number: 170
Status: Developing
Requires: RFC 164
=head1 ABSTRACT
Currently, C<=~> is only available for use in specific builtin pattern
matches. This is too bad, because it's really a neat operator.
This RFC proposes a simple way to make it more general-purpose.
=head1 DESCRIPTION
First off, this assumes RFC 164. Second, it requires you drop any
knowledge of how C<=~> currently works. Finally, it runs directly
counter to RFC 139, which proposes another application for C<=~>.
This RFC proposes a simple use for C<=~>: as a last-argument rvalue
duplicator. What this means is that an expression such as this:
$value = dostuff($arg1, $arg2, $value);
Could now be rewritten as:
$value =~ dostuff($arg1, $arg2);
And C<$value> would be implicitly transferred over to the right side as
the last argument. It's simple, but it makes what is being operated on
very obvious.
This enables us to rewrite the following constructs:
($name) = split /\s+/, $name;
$string = quotemeta($string);
@array = reverse @array;
@vals = sort { $a <=> $b } @vals;
$string = s/\s+/SPACE/, $string; # RFC 164
$matches = m/\w+/, $string; # RFC 164
@strs = s/foo/bar/gi, @strs; # RFC 164
As the shorter and more readable:
($name) =~ split /\s+/;
$string =~ quotemeta;
@array =~ reverse;
@vals =~ sort { $a <=> $b };
$string =~ s/\s+/SPACE/; # looks familiar
$string =~ m/\w+/; # this too [1]
@strs =~ s/foo/bar/gi; # cool extension
It's a simple solution, true, but it has a good amount of flexibility
and brevity. It could also be the case that multiple values could be
called and returned, so that:
($name, $email) = special_parsing($name, $email);
Becomes:
($name, $email) =~ special_parsing;
Again, it's simple, but seems to have useful applications.
=head1 IMPLEMENTATION
Simplistic (hopefully).
=head1 MIGRATION
This introduces new functionality, which allows backwards compatibility
for regular expressions. As such, it should require no special
translation of code. This RFC assumes RFC 164 will be adopted (which it
may not be) for changes to regular expressions.
True void contexts may also render some parts of this moot, in which
case coming up with a more advanced use for C<=~> may be desirable.
=head1 NOTES
[1] That m// one doesn't quite work right, but that's a special case
that I would suggest should be caught by some other part of the grammar
to maintain backwards compatability (like bare //).
=head1 REFERENCES
RFC 164: Replace =~, !~, m//, and s/// with match() and subst()
RFC 139: Allow Calling Any Function With A Syntax Like s///
