Re: Overloading ref() just like ->isa and ->can

What would be the best practice method for determining if something is a hash or array? At times I want to know that the underlying object is a hashref, even if it has been blessed. e.g.

use strict;
use warnings;
{
    package foo;
    sub new { bless {}, shift};
}
my $foo = foo->new();
print "ref(foo) = ",ref($foo), "\n";
print "foo is a hash\n" if UNIVERSAL::isa($foo,'HASH');


my $bar = {a => 1};
# The following won't work 
# print "bar is a hash\n" if $bar->isa('HASH');

print "bar is a hash\n" if UNIVERSAL::isa($bar,'HASH');
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Comment on Re: Overloading ref() just like ->isa and ->can - best practice for isa(HASH)? Download Code

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Re^2: Overloading ref() just like ->isa and ->can - best practice for isa(HASH)? by diotalevi (Canon) on Aug 22, 2006 at 19:12 UTC
If you want to know whether it really, truely is a hash, see if SVt_PVHV is true for the SV. See sv.h for the dirt. `use B qw( svref_2object SVt_PVHV ); sub is_hash { my $ref = shift @_; return ref( $ref ) and svref_2object( $ref ) & SVt_PVHV; }` [download] If you just want to know whether it supports being treated like a hash, do something akin to a ->can test for hash-ness. If the hash dereference doesn't die, then `$ref` acts like a hash. `sub does_hash { my $ref = shift @_; return ref( $ref ) and eval { %$ref; 1 }; }` [download] ⠤⠤ ⠙⠊⠕⠞⠁⠇⠑⠧⠊	[reply] [d/l] [select]

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Re^2: Overloading ref() just like ->isa and ->can - best practice for isa(HASH)?
by diotalevi (Canon) on Aug 22, 2006 at 19:12 UTC

If you want to know whether it really, truely is a hash, see if SVt_PVHV is true for the SV. See sv.h for the dirt.

use B qw( svref_2object SVt_PVHV );
sub is_hash {
    my $ref = shift @_;
    return ref( $ref )
        and svref_2object( $ref ) & SVt_PVHV;
}
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If you just want to know whether it supports being treated like a hash, do something akin to a ->can test for hash-ness. If the hash dereference doesn't die, then $ref acts like a hash.

sub does_hash {
    my $ref = shift @_;
    return ref( $ref )
        and eval { %$ref; 1 };
}
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