NAME

Ref::Util - Utility functions for checking references

DESCRIPTION

Ref::Util introduces several functions to help identify references in a faster and smarter way. In short:

ref $foo eq 'ARRAY'

# is now:

is_arrayref($foo)

The difference:

• No comparison against a string constant

  When you call ref, you stringify the reference and then compare it to some string constant (like ARRAY or HASH). Not just awkward, it's brittle since you can mispell the string.

• Supports blessed variables

  When calling ref, you receive either the reference type (SCALAR, ARRAY, HASH, etc.) or the package it's blessed into.

  When calling is_arrayref (et. al.), you check the variable flags, so even if it's blessed, you know what type of variable is blessed.

  my $foo = bless {}, 'PKG';
  ref($foo) eq 'HASH'; # fails
  
  use Ref::Util 'is_hashref';
  my $foo = bless {}, 'PKG';
  is_hashref($foo); # works

• Supports overloaded variables

  If you've overloaded anything (eq, stringification), you will probably get bitten. However, these functions do not care since they only check flags.

Additionally, two implementations are available, depending on the perl version you have. For perl that supports Custom OPs, we actually add an OP code (which is faster), and for perls that do not, we include an implementation that just calls an XS function - which is still faster than the Pure-Perl equivalent.

We might also introduce a Pure-Perl version of everything, allowing to install this module where a compiler is not available, making the XS parts optional.

SUBROUTINES

is_scalarref($ref)

Check for a scalar reference.

is_scalarref(\"hello");
is_scalarref(\30);
is_scalarref(\$value);

is_arrayref($ref)

Check for an array reference.

is_arrayref([]);

is_hashref($ref)

Check for a hash reference.

is_hashref({});

is_coderef($ref)

Check for a code reference.

is_coderef( sub {} );

is_regexpref($ref)

Check for a regular expression (regex, regexp) reference.

is_regexpref( qr// );

is_globref($ref)

Check for a glob reference.

is_globref( \*STDIN );

is_formatref($ref)

Check for a format reference.

# set up format in STDOUT
format STDOUT =
.

# now we can test it
is_formatref( *main::STDOUT{'FORMAT'} );

is_ioref($ref)

Check for an IO reference.

is_ioref( *STDOUT{IO} );

SEE ALSO

• Params::Classify

THANKS

The following people have been invaluable in their feedback and support.

• Yves Orton

• Steffen Müller

• Jarkko Hietaniemi

• Mattia Barbon

AUTHORS

• Vikentiy Fesunov

• Sawyer X

• Gonzalo Diethelm

• p5pclub

cpanm Ref::Util

perl -MCPAN -e shell
install Ref::Util