Class::...r::hash(3)

🌸 NAME 🌸

okay bestie, so this manual page is Class::Method::hash — the page header renders it as Class::...r::hash(3) — and it's filed under User Contributed Perl Documentation. It's literally about creating methods for handling a hash value. We love a hash-handling moment 💅.

✨ SYNOPSIS ✨

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

💖 DESCRIPTION 💖

This module creates methods to handle hash values in an object. For a component named x, by default it creates these 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. (Yes, all of them. no cap.)

The methods available are:

✨ * ✨

Created by default. This method returns the list of keys and values stored in the slot — returned pairwise, i.e. key, value, key, value; and as with Perl hashes, no order of keys is guaranteed. If you pass any arguments to this method, they replace the current hash contents. In an array context it returns the keys and values as an array, and in a scalar context as a hash-reference. Heads up: this reference is no longer a direct reference to the storage, in contrast to Class::MethodMaker v1 — that's to protect encapsulation. See x_ref if you need that functionality (and are prepared to take the associated risk, bestie).

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; it deletes any associated storage and returns the component to its default state. Normally, this means *_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). Yes, that extra ) is in the page; we're keeping it exactly 💀.

✨ *_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 the whole component is 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 — yes, the page says "has"; I'm not editing it, bestie 💀. 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).

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and that's the whole vibe, bestie — this Class::...r::hash(3) page's source/version says perl v5.42.0, and the date on it is 2025-07-25. go off, hash methods 💖✨