NAME

    Filter::signatures - very simplicistic signatures for Perl < 5.20

SYNOPSIS

        use Filter::signatures;
        no warnings 'experimental::signatures'; # does not raise an error
        use feature 'signatures'; # this now works on <5.16 as well
    
        sub hello( $name ) {
            print "Hello $name\n";
        }
    
        hello("World");
    
        sub hello2( $name="world" ) {
            print "Hello $name\n";
        }
        hello2(); # Hello world

CAVEATS

    This implements a very simplicistic transform to allow for using very
    simplicistic named formal arguments in subroutine declarations. This
    module does not implement warning if more parameters than expected are
    passed in.

    The module also implements default values for unnamed parameters by
    splitting the formal parameters on /,/ and assigning the values if @_
    contains fewer elements than expected. Function calls as default values
    may work by accident. Commas within default values happen to work due
    to the design of Filter::Simple, which removes them for the application
    of this filter.

    Note that this module inherits all the bugs of Filter::Simple and
    potentially adds some of its own. Most notable is that Filter::Simple
    sometimes will misinterpret the division operator / as a leading
    character to starting a regex match:

        my $wait_time = $needed / $supply;

    This will manifest itself through syntax errors appearing where
    everything seems in order. The hotfix is to add a comment to the code
    that "closes" the misinterpreted regular expression:

        my $wait_time = $needed / $supply; # / for Filter::Simple

    A better hotfix is to upgrade to Perl 5.20 or higher and use the native
    signatures support there. No other code change is needed, as this
    module will disable its functionality when it is run on a Perl
    supporting signatures.

 eval

    It seems that Filter::Simple does not trigger when using code such as

      eval <<'PERL';
          use Filter::signatures;
          use feature 'signatures';
    
          sub foo (...) {
          }
      PERL

    So, creating subroutines with signatures from strings won't work with
    this module. The workaround is to upgrade to Perl 5.20 or higher.

ENVIRONMENT

    If you want to force the use of this module even under versions of Perl
    that have native support for signatures, set
    $ENV{FORCE_FILTER_SIGNATURES} to a true value before the module is
    imported.

SEE ALSO

    "Signatures" in perlsub

    signatures - a module that doesn't use a source filter but optree
    modification instead

    Sub::Signatures

REPOSITORY

    The public repository of this module is
    http://github.com/Corion/filter-signatures.

SUPPORT

    The public support forum of this module is https://perlmonks.org/.

BUG TRACKER

    Please report bugs in this module via the RT CPAN bug queue at
    https://rt.cpan.org/Public/Dist/Display.html?Name=Filter-signatures or
    via mail to filter-signatures-Bugs@rt.cpan.org.

AUTHOR

    Max Maischein corion@cpan.org

COPYRIGHT (c)

    Copyright 2015-2016 by Max Maischein corion@cpan.org.

LICENSE

    This module is released under the same terms as Perl itself.