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