NAME
Sub::Infix - create a fake infix operator
SYNOPSIS
use Sub::Infix;
# Operator needs to be defined (or imported) at compile time.
BEGIN { *plus = infix { $_[0] + $_[1] } };
my $five = 2 |plus| 3;
DESCRIPTION
Sub::Infix creates fake infix operators using overloading. It doesn't use
source filters, or Devel::Declare, or any of that magic. (Though
Devel::Declare isn't magic enough to define infix operators anyway; I
know; I've tried.) It's pure Perl, has no non-core dependencies, and runs
on Perl 5.8.
The price you pay for its simplicity is that you cannot define an operator
that can be used like this:
my $five = 2 plus 3;
Instead, the operator needs to be wrapped with real Perl operators in one
of three ways:
my $five = 2 |plus| 3;
my $five = 2 /plus/ 3;
my $five = 2 <<plus>> 3;
The advantage of this is that it gives you three different levels of
operator precedence.
You can also call the function a slightly less weird way:
my $five = plus->(2, 3);
How does it work?
`2 |plus| 3` is parsed by perl as: `2 | ( &plus() | 3 )`.
`&plus()` returns an object that overloads the `|` operator; let's call
that $obj.
The overloaded `$obj | 3` operation stashes 3 inside $obj noting that the
number is the right operand, and returns $obj.
Then `2 | $obj` is evaluated, stashing 2 inside $obj as the left operand.
At this point, the object notices that it has both operands, and calls the
coderef from the definition of the operator, passing it both operands.
BUGS
Please report any bugs to
<
http://rt.cpan.org/Dist/Display.html?Queue=Sub-Infix>.
SEE ALSO
<
http://code.activestate.com/recipes/384122-infix-operators/>.
AUTHOR
Toby Inkster <
[email protected]>.
COPYRIGHT AND LICENCE
This software is copyright (c) 2013-2014 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under the
same terms as the Perl 5 programming language system itself.
DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
