Class::Method::hash - Create methods for handling a hash value.
use Class::MethodMaker
[ hash => [qw/ x /] ];
$instance->x; # empty
$instance->x(a => 1, b => 2, c => 3);
$instance->x_count == 3; # true
$instance->x = (b => 5, d => 8); # Note this *replaces* the hash,
# not adds to it
$instance->x_index('b') == 5; # true
$instance->x_exists('c'); # false
$instance->x_exists('d'); # true
Creates methods to handle hash values in an object. For a component named
"x", by default creates methods "x", "x_reset",
"x_clear", "x_isset", "x_count",
"x_index", "x_keys", "x_values",
"x_each", "x_exists", "x_delete",
"x_set", "x_get".
Methods available are:
"*"
Created by default. This method returns the list of keys and values
stored in the slot (they are returned pairwise, i.e., key, value, key, value;
as with perl hashes, no order of keys is guaranteed). If any arguments are
provided to this method, they
replace the current hash contents. In an
array context it returns the keys, values as an array and in a scalar context
as a hash-reference. Note that this reference is no longer a direct reference
to the storage, in contrast to Class::MethodMaker v1. This is to protect
encapsulation. See x_ref if you need that functionality (and are prepared to
take the associated risk.)
If a single argument is provided that is an arrayref or hashref, it is expanded
and its contents used in place of the existing contents. This is a more
efficient passing mechanism for large numbers of values.
*_reset
Created by default. Called without an argument, this resets the component
as a whole; deleting any associated storage, and returning the component to
its default state. Normally, this means that
*_isset will return false,
and
* will return undef. If "-default" is in effect, then the
component will be set to the default value, and
*_isset will return
true. If "-default_ctor" is in effect, then the default subr will be
invoked, and its return value used to set the value of the component, and
*_isset will return true.
If called with arguments, these arguments are treated as indexes into the
component, and the individual elements thus referenced are reset (their
storage deleted, so that
*_isset(n) will return false for appropriate
n, except where "-default" or "-default_ctor" are
in force, as above). As with perl arrays, resetting the highest set value
implicitly decreases the count (but
x_reset(n) never unsets the aggregate
itself, even if all the elements are not set).
*_clear
Created by default. Empty the component of all elements, but without
deleting the storage itself.
If given a list of keys, then the elements
that exist indexed by those
keys are set to undef (but not deleted).
Note the very different semantics: "$x->a_clear('b')" sets the
value of "b" in component 'a' to undef (if "b") already
exists (so "$x->a_isset('b'))" returns true), but
"$x->a_clear()" deletes the element "b" from component
'a' (so "$x->a_isset('b'))" returns false).
*_isset
Created by default. Whether the component is currently set. This is
different from being defined; initially, the component is not set (and if
read, will return undef); it can be set to undef (which is a set value, which
also returns undef). Having been set, the only way to unset the component is
with *_reset.
If a default value is in effect, then *_isset will always return true.
*_isset() tests the component as a whole.
*_isset(a) tests the element indexed by
a.
*_isset(a,b)
tests the elements indexed by
a,
b, and returns the logical
conjunction (
and) of the tests.
*_count
Created by default. Returns the number of elements in this component.
This is not affected by presence (or lack) of a "default" (or
"default_ctor"). Returns "undef" if whole component not
set (as per
*_isset).
*_index
Created by default. Takes a list of indices, returns a list of the
corresponding values.
If a default (or a default ctor) is in force, then a lookup by index will vivify
& set to the default the respective elements (and therefore the aggregate
data-structure also, if it's not already).
*_keys
Created by default. The known keys, as a list in list context, as an
arrayref in scalar context.
If you're expecting a count of the keys in scalar context, see
*_count.
*_values
Created by default. The known values, as a list in list context, as an
arrayref in scalar context.
*_each
Created by default. The next pair of key, value (as a list) from the
hash.
*_exists
Created by default. Takes any number of arguments, considers each as a
key, and determines whether the key exists in the has. Returns the logical
conjunction (
and).
*_delete
Created by default. This operates exactly like
*_reset, except
that calling this with no args does nothing. This is provided for
orthogonality with the Perl "delete" operator, while
*_reset
is provided for orthogonality with other component types.
*_set
%n = $x->h; # (a=>1,b=>2,c=>3) (in some order)
$h->h_set(b=>4,d=>7);
%n = $h->a; # (a=>1,b=>4,c=>3,d=>7) (in some order)
Created by default. Takes a list, treated as pairs of index => value;
each given index is set to the corresponding value. No return.
If two arguments are given, of which the first is an arrayref, then it is
treated as a list of indices of which the second argument (which must also be
an arrayref) are the corresponding values. Thus the following two commands are
equivalent:
$x->a_set(b=>4,d=>7);
$x->a_set(['b','d'],[4,7]);
*_get
Created by default. Retrieves the value of the component without setting
(ignores any arguments passed).