NAME

Sub::Boolean - make XS true/false subs

SYNOPSIS

  use Test::More;
  use Sub::Boolean qw( make_true );
  
  make_true( __PACKAGE__ . "::foobar" );
  
  ok( foobar(),    'returns true' );
  ok( foobar(123), 'returns true' );

DESCRIPTION

A good way to create fast true/false constants is:

  use constant { true => !!1, false => !!0 };

Or on newer Perls:

  use builtin qw( true false );

However these constants will throw a compile-time error if you call them as a sub:

  if ( true(123) ) {
    ...;
  }

Sub::Boolean allows you to create subs which return true or false fast as they're implemented in XS.

As a bonus, it can also generate subs which return undef or the empty list.

Each function created by this module will have a different refaddr, which means that using things like set_prototype or set_subname on one will not affect others.

Boolean functions are really unlikely to be a bottleneck in most applications, so the use cases for this module are very limited.

FUNCTIONS

Nothing is exported unless requested.

make_true( $qualified_name )

Given a fully qualified sub name, installs a sub something like:

  sub $qualified_name {
    return !!1;
  }

If called as make_true() with no name, returns an anonymous coderef.

make_false( $qualified_name )

Given a fully qualified sub name, installs a sub something like:

  sub $qualified_name {
    return !!0;
  }

If called as make_false() with no name, returns an anonymous coderef.

make_undef( $qualified_name )

Given a fully qualified sub name, installs a sub something like:

  sub $qualified_name {
    return undef;
  }

If called as make_undef() with no name, returns an anonymous coderef.

make_empty( $qualified_name )

Given a fully qualified sub name, installs a sub something like:

  sub $qualified_name {
    return ();
  }

If called as make_empty() with no name, returns an anonymous coderef.

BUGS

Please report any bugs to https://github.com/tobyink/p5-sub-boolean/issues.

SEE ALSO

builtin, constant.

AUTHOR

Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE

This software is copyright (c) 2022 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.

cpanm Sub::Boolean

perl -MCPAN -e shell
install Sub::Boolean