perl-Ref-Util

Ref::Util introduces several functions to help identify references in a
smarter (and usually faster) way. In short:
ref( $foo ) eq 'ARRAY'              is_plain_arrayref( $foo )

use Scalar::Util qw( reftype );
reftype( $foo ) eq 'ARRAY'          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.
If you use Scalar::Util's 'reftype', you still compare it as a string:
if ( reftype($foo) eq 'ARRAY' ) { ... }




Supports blessed variables



Note: In future versions, the idea is to make the default functions use
the plain variation, which means explicitly non-blessed references.
If you want to explicitly check for blessed references, you should use
the 'is_blessed_' functions. There will be an 'is_any_' variation which
will act like the current main functions - not caring whether it's blessed
or not.
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


On the other hand, in some situations it might be better to specifically
exclude blessed references. The rationale for that might be that merely
because some object happens to be implemented using a hash doesn't mean
it's necessarily correct to treat it as a hash. For these situations, you
can use 'is_plain_hashref' and friends, which have the same performance
benefits as 'is_hashref'.
There is also a family of functions with names like 'is_blessed_hashref';
these return true for blessed object instances that are implemented using
the relevant underlying type.


Supports tied variables and magic



Tied variables (used in Readonly, for example) are supported.
use Ref::Util qw<is_plain_hashref>;
use Readonly;

Readonly::Scalar my $rh2 => { a => { b => 2 } };
is_plain_hashref($rh2); # success


Ref::Util added support for this in 0.100. Prior to this version the test
would fail.


Ignores overloading



These functions ignore overloaded operators and simply check the variable
type. Overloading will likely not ever be supported, since I deem it
problematic and confusing.
Overloading makes your variables opaque containers and hides away what
they are and instead require you to figure out how to use them. This
leads to code that has to test different abilities (in 'eval', so it
doesn't crash) and to interfaces that get around what a person thought you
would do with a variable. This would have been alright, except there is no
clear way of introspecting it.


Ignores subtle types:



The following types, provided by Scalar::Util's 'reftype', are not
supported:


'VSTRING'



This is a 'PVMG' ("normal" variable) with a flag set for VSTRINGs. Since
this is not a reference, it is not supported.


'LVALUE'



A variable that delegates to another scalar. Since this is not a reference,
it is not supported.


'INVLIST'



I couldn't find documentation for this type.
Support might be added, if a good reason arises.


Usually fast



When possible, Ref::Util uses Ref::Util::XS as its implementation. (If you
don't have a C compiler available, it uses a pure Perl fallback that has
all the other advantages of Ref::Util, but isn't as fast.)
In fact, Ref::Util::XS has two alternative implementations available
internally, depending on the features supported by the version of Perl
you're using. For Perls that supports custom OPs, we actually add an OP
(which is faster); for other Perls, the implementation that simply calls an
XS function (which is still faster than the pure-Perl equivalent).
See below for benchmark results.

          

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License: MIT
URL: http://search.cpan.org/dist/Ref-Util/