Signature(3pm) User Contributed Perl Documentation Signature(3pm)
NAME
perl5i::Signature - Representing what parameters a subroutine accepts
SYNOPSIS
func hello( $greeting, $place ) { say "$greeting, $place" }
my $code = &hello;
my $signature = $code->signature;
say $signature->num_positional_params; # 2
say $signature->is_method; # false
DESCRIPTION
A Signature is a representation of what parameters a subroutine accepts. Each subroutine defined with "func" or "method" will have a
signature associated with it. You can get at it by calling the "signature" method on the code reference. See "Signature Introspection" in
perl5i for more details.
Subroutines declared with Perl's built in "sub" will have no signature.
METHODS
params
my $params = $sig->params;
An array ref of the parameters a subroutine takes in the order it takes them. Currently they are just strings. In the future they will be
string overloaded objects.
positional_params
my $params = $sig->positional_params;
Like "$sig->params" but it is just the positional parameters.
In the future there will be named parameters.
num_positional_params
my $num_positional_params = $sig->num_positional_params;
The number of named parameters the subroutine takes.
In the future there will be named parameters. For the purposes of determining how many arguments a function takes, it is most useful to
look just at the positional ones.
This is mostly an optimization for "$sig->positional_params->size".
as_string
my $params = $sig->as_string;
The original signature string.
invocant
my $invocant = $sig->invocant;
The invocant is the object or class a method is called on. "invocant" will return the parameter which contains this, by default it is
$self on a method, and nothing a regular subroutine.
is_method
my $is_method = $sig->is_method;
Returns if the subroutine was declared as a method.
OVERLOADING
Signature objects are string overloaded to return "as_string". They are also always true to avoid objects taking no parameters from being
confused with subroutines with no signatures.
perl v5.14.2 2012-06-14 Signature(3pm)