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 exlements 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.