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.IX Title "Sub::Infix 3pm"
.TH Sub::Infix 3pm 2024-03-08 "perl v5.38.2" "User Contributed Perl Documentation"
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.SH NAME
Sub::Infix \- create a fake infix operator
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&   use Sub::Infix;
\&   
\&   # Operator needs to be defined (or imported) at compile time.
\&   BEGIN { *plus = infix { $_[0] + $_[1] } };
\&   
\&   my $five = 2 |plus| 3;
.Ve
.SH DESCRIPTION
.IX Header "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 5.6.
.PP
The price you pay for its simplicity is that you cannot define an
operator that can be used like this:
.PP
.Vb 1
\&   my $five = 2 plus 3;
.Ve
.PP
Instead, the operator needs to be wrapped with real Perl operators in
one of three ways:
.PP
.Vb 3
\&   my $five = 2 |plus| 3;
\&   my $five = 2 /plus/ 3;
\&   my $five = 2 <<plus>> 3;
.Ve
.PP
The advantage of this is that it gives you three different levels of
operator precedence.
.PP
You can also call the function a slightly less weird way:
.PP
.Vb 1
\&   my $five = plus\->(2, 3);
.Ve
.SS "How does it work?"
.IX Subsection "How does it work?"
\&\f(CW\*(C`2 |plus| 3\*(C'\fR is parsed by perl as: \f(CW\*(C`2 | ( &plus() | 3 )\*(C'\fR.
.PP
\&\f(CW&plus()\fR returns an object that overloads the \f(CW\*(C`|\*(C'\fR operator;
let's call that \f(CW$obj\fR.
.PP
The overloaded \f(CW\*(C`$obj | 3\*(C'\fR operation stashes \f(CW3\fR inside
\&\f(CW$obj\fR noting that the number is the right operand, and returns
\&\f(CW$obj\fR.
.PP
Then \f(CW\*(C`2 | $obj\*(C'\fR is evaluated, stashing \f(CW2\fR inside \f(CW$obj\fR
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.
.SH BUGS
.IX Header "BUGS"
Please report any bugs to
<http://rt.cpan.org/Dist/Display.html?Queue=Sub\-Infix>.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
<http://code.activestate.com/recipes/384122\-infix\-operators/>.
.SH AUTHOR
.IX Header "AUTHOR"
Toby Inkster <tobyink@cpan.org>.
.SH "COPYRIGHT AND LICENCE"
.IX Header "COPYRIGHT AND LICENCE"
This software is copyright (c) 2013\-2014 by Toby Inkster.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
.SH "DISCLAIMER OF WARRANTIES"
.IX Header "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.