Function::Parameters::Info - Information about parameter lists
use Function::Parameters; fun foo($x, $y, :$hello, :$world = undef) {} my $info = Function::Parameters::info \&foo; my $p0 = $info->invocant; # undef my @p1 = $info->positional_required; # ('$x', '$y') my @p2 = $info->positional_optional; # () my @p3 = $info->named_required; # ('$hello') my @p4 = $info->named_optional; # ('$world') my $p5 = $info->slurpy; # undef my $min = $info->args_min; # 4 my $max = $info->args_max; # inf my $invocant = Function::Parameters::info(method () { 42 })->invocant; # '$self' my $slurpy = Function::Parameters::info(fun {})->slurpy; # '@_'
Function::Parameters::info returns objects of this class to describe parameter lists of functions. The following methods are available:
Function::Parameters::info
Returns the name of the variable into which the first argument is shifted automatically, or undef if no such thing exists. This will usually return '$self' for methods.
shift
undef
'$self'
Returns a list of the names of the required positional parameters (or a count in scalar context).
Returns a list of the names of the optional positional parameters (or a count in scalar context).
Returns a list of the names of the required named parameters (or a count in scalar context).
Returns a list of the names of the optional named parameters (or a count in scalar context).
Returns the name of the final array or hash that gobbles up all remaining arguments, or undef if no such thing exists.
As a special case, functions defined without an explicit parameter list (i.e. without ( )) will return '@_' here because they accept any number of arguments.
( )
'@_'
Returns the minimum number of arguments this function requires. This is computed as follows: Invocant and required positional parameters count 1 each. Optional parameters don't count. Required named parameters count 2 each (key + value). Slurpy parameters don't count either because they accept empty lists.
Returns the maximum number of arguments this function accepts. This is computed as follows: If there is any named or slurpy parameter, the result is Inf. Otherwise the result is the sum of all invocant and positional parameters.
Inf
All the methods described above actually return parameter objects wherever the description says "name". These objects have two methods: name, which returns the name of the parameter (as a plain string), and type, which returns the corresponding type constraint object (or undef if there was no type specified).
name
type
This should be invisible if you don't use types because the objects also overload stringification to call name. That is, if you treat parameter objects like strings, they behave like strings (i.e. their names).
Function::Parameters
Lukas Mai, <l.mai at web.de>
<l.mai at web.de>
Copyright 2013 Lukas Mai.
This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.
See http://dev.perl.org/licenses/ for more information.
To install Function::Parameters, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Function::Parameters
CPAN shell
perl -MCPAN -e shell install Function::Parameters
For more information on module installation, please visit the detailed CPAN module installation guide.