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Sub::Infix - create a fake infix operator

Author

       Toby Inkster <tobyink@cpan.org>.

Bugs

       Please report any bugs to <http://rt.cpan.org/Dist/Display.html?Queue=Sub-Infix>.

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.

       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);

   Howdoesitwork?
       "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.

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.

perl v5.40.1                                       2025-07-26                                    Sub::Infix(3pm)

Name

       Sub::Infix - create a fake infix operator

See Also

Synopsis

          use Sub::Infix;

          # Operator needs to be defined (or imported) at compile time.
          BEGIN { *plus = infix { $_[0] + $_[1] } };

          my $five = 2 |plus| 3;

See Also