Hash::AsObject(3pm)					User Contributed Perl Documentation				       Hash::AsObject(3pm)

NAME

       Hash::AsObject - treat hashes as objects, with arbitrary accessors/mutators

SYNOPSIS

	   $h = Hash::AsObject->new;
	   $h->foo(123);
	   print $h->foo;	# prints 123
	   print $h->{'foo'};	# prints 123
	   $h->{'bar'}{'baz'} = 456;
	   print $h->bar->baz;	# prints 456

DESCRIPTION

       A Hash::AsObject is a blessed hash that provides read-write access to its elements using accessors.  (Actually, they're both accessors and
       mutators.)

       It's designed to act as much like a plain hash as possible; this means, for example, that you can use methods like "DESTROY" to get or set
       hash elements with that name.  See below for more information.

METHODS

       The whole point of this module is to provide arbitrary methods.	For the most part, these are defined at runtime by a specially written
       "AUTOLOAD" function.

       In order to behave properly in all cases, however, a number of special methods and functions must be supported.	Some of these are defined
       while others are simply emulated in AUTOLOAD.

       new
	       $h = Hash::AsObject->new;
	       $h = Hash::AsObject->new(\%some_hash);
	       $h = Hash::AsObject->new(%some_other_hash);

	   Create a new Hash::AsObject.

	   If called as an instance method, this accesses a hash element 'new':

	       $h->{'new'} = 123;
	       $h->new;       # 123
	       $h->new(456);  # 456

       isa This method cannot be used to access a hash element 'isa', because Hash::AsObject doesn't attempt to handle it specially.

       can Similarly, this can't be used to access a hash element 'can'.

       AUTOLOAD
	       $h->{'AUTOLOAD'} = 'abc';
	       $h->AUTOLOAD;	   # 'abc'
	       $h->AUTOLOAD('xyz') # 'xyz'

	   Hash::AsObject::AUTOLOAD recognizes when AUTOLOAD is begin called as an instance method, and treats this as an attempt to get or set
	   the 'AUTOLOAD' hash element.

       DESTROY
	       $h->{'DESTROY'} = [];
	       $h->DESTROY;    # []
	       $h->DESTROY({}) # {}

	   "DESTROY" is called automatically by the Perl runtime when an object goes out of scope.  A Hash::AsObject can't distinguish this from a
	   call to access the element $h->{'DESTROY'}, and so it blithely gets (or sets) the hash's 'DESTROY' element; this isn't a problem, since
	   the Perl interpreter discards any value that DESTROY returns when called automatically.

       VERSION
	   When called as a class method, this returns $Hash::AsObject::VERSION; when called as an instance method, it gets or sets the hash
	   element 'VERSION';

       import
	   Since Hash::AsObject doesn't export any symbols, this method has no special significance and you can safely call it as a method to get
	   or set an 'import' element.

	   When called as a class method, nothing happens.

       The methods "can()" and "isa()" are special, because they're defined in the "UNIVERSAL" class that all packages automatically inherit from.
       Unfortunately, this means that you can't use Hash::AsObject to access elements 'can' and 'isa'.

CAVEATS

       No distinction is made between non-existent elements and those that are present but undefined.  Furthermore, there's no way to delete an
       element without resorting to "delete $h->{'foo'}".

       Storing a hash directly into an element of a Hash::AsObject instance has the effect of blessing that hash into Hash::AsObject.

       For example, the following code:

	   my $h = Hash::AsObject->new;
	   my $foo = { 'bar' => 1, 'baz' => 2 };
	   print ref($foo), "
";
	   $h->foo($foo);
	   print ref($foo), "
";

       Produces the following output:

	   HASH
	   Hash::AsObject

       I could fix this, but then code like the following would throw an exception, because "$h->foo($foo)" will return a plain hash reference,
       not an object:

	   $h->foo($foo)->bar;

       Well, I can make "$h->foo($foo)->bar" work, but then code like this won't have the desired effect:

	   my $foo = { 'bar' => 123 };
	   $h->foo($foo);
	   $h->foo->bar(456);
	   print $foo->{'bar'};  # prints 123
	   print $h->foo->bar;	 # prints 456

       I suppose I could fix that, but that's an awful lot of work for little apparent benefit.

       Let me know if you have any thoughts on this.

BUGS

       Autovivification is probably not emulated correctly.

       The blessing of hashes stored in a Hash::AsObject might be considered a bug.  Or a feature; it depends on your point of view.

TO DO

       o   Add the capability to delete elements, perhaps like this:

	       use Hash::AsObject 'deleter' => 'kill';
	       $h = Hash::AsObject->new({'one' => 1, 'two' => 2});
	       kill $h, 'one';

	   That might seem to violate the prohibition against exporting functions from object-oriented packages, but then technically it wouldn't
	   be exporting it from anywhere since the function would be constructed by hand.  Alternatively, it could work like this:

	       use Hash::AsObject 'deleter' => 'kill';
	       $h = Hash::AsObject->new({'one' => 1, 'two' => 2});
	       $h->kill('one');

	   But, again, what if the hash contained an element named 'kill'?

       o   Define multiple classes in "Hash/AsObject.pm"?  For example, there could be one package for read-only access to a hash, one for hashes
	   that throw exceptions when accessors for non-existent keys are called, etc.	But this is hard to do fully without (a) altering the
	   underlying hash, or (b) defining methods besides AUTOLOAD. Hmmm...

VERSION

       0.06

AUTHOR

       Paul Hoffman <nkuitse AT cpan DOT org>

CREDITS

       Andy Wardley for Template::Stash, which was my inspiration.  Writing template code like this:

	   [% foo.bar.baz(qux) %]

       Made me yearn to write Perl code like this:

	   foo->bar->baz($qux);

COPYRIGHT

       Copyright 2003-2007 Paul M. Hoffman. All rights reserved.

       This program is free software; you can redistribute it and modify it under the same terms as Perl itself.

perl v5.10.1							    2010-04-24						       Hash::AsObject(3pm)