AptPkg::hash--3pm

AptPkg::hash(3pm)     User Contributed Perl Documentation    AptPkg::hash(3pm)



NAME
       AptPkg::hash - a helper class for implementing tied hashes

SYNOPSIS
       use AptPkg::hash;

DESCRIPTION
       The AptPkg::hash class provides hash-like access for objects which have
       an underlying XS implementation.

       Such objects need to add AptPkg::hash to @ISA, provide get, set and
       exists methods, and an iterator class.

       AptPkg::hash


       new([XS_OBJECT])
           Create a object as a tied hash.  The object is implemented as a
           hash reference blessed into the class, which in turn is tied to
           AptPkg::hash.

           This means that both $obj->method() and $obj->{key} valid, the lat-
           ter invoking get/set (through FETCH/STORE).

           The tie associates an array reference with the hash, which ini-
           tially contains a reference to the hash, the XS object and an anon
           hash which may be used by subclasses to store state information.
           The fourth element is used to store the current iterator.

           If no XS object is passed, one is created via new in the XS class.
           The name of that class is constructed from the class name, by
           lower-casing the last component and prefixing it with an underscore
           (eg. AptPkg::Config becomes AptPkg::_config).

           If the module contains a @KEYS array, then the private hash will be
           populated with those entries as keys (see the description below of
           the AptPkg::hash::method class).

       _self, _xs, _priv, _iter
           Accessors which may be used in subclass methods to fetch the four
           array elements associated with the hash reference.

       keys(ARGS)
           In a scalar context, creates and returns a new iterator object (the
           class name with the suffix ::Iter appended).

           The XS object, the private hash and any arguments are passed to the
           constructor.

           In an array context, the iterator is used to generate a list of
           keys which are then returned.

           The iterator class must implement a next method, which returns the
           current key and advances to the next.

       AptPkg::hash::method

       The AptPkg::hash::method class extends AptPkg::hash, providing a simple
       way to map a fixed set of keys (defined by the @KEYS array) into method
       calls on either the object, or the internal XS object.

       Classes inheriting from AptPkg::hash::method should provide an iterator
       class which inherits from AptPkg::hash::method::iter.

AUTHOR
       Brendan O'Dea <bod AT debian.org>



perl v5.8.8                       2005-08-07                 AptPkg::hash(3pm)