Help language development. Donate to The Perl Foundation
Array::Agnostic - be an array without knowing how
use Array::Agnostic;
class MyArray does Array::Agnostic {
method AT-POS() { ... }
method elems() { ... }
}
my @a is MyArray = 1,2,3;
This module makes an Array::Agnostic role available for those classes that wish to implement the Positional role as an Array. It provides all of the Array functionality while only needing to implement 5 methods:
method AT-POS($position) { ... } # simple case
method AT-POS($position) { Proxy.new( FETCH => { ... }, STORE => { ... } }
Return the value at the given position in the array. Must return a Proxy that will assign to that position if you wish to allow for auto-vivification of elements in your array.
method elems(--> Int:D) { ... }
Return the number of elements in the array (defined as the index of the highest element + 1).
You may implement these methods out of performance reasons yourself, but you don't have to as an implementation is provided by this role. They follow the same semantics as the methods on the Array object.
In alphabetical order: append, Array, ASSIGN-POS, end, gist, grab, iterator, keys, kv, list, List, new, pairs, perl, pop, prepend, push, shape, shift, Slip, STORE, Str, splice, unshift, values
These methods may be implemented by the consumer for performance reasons or to provide a given capability.
method BIND-POS($position, $value) { ... }
Bind the given value to the given position in the array, and return the value. Will throw an exception if called and not implemented.
method DELETE-POS($position) { ... }
Mark the element at the given position in the array as absent (make EXISTS-POS return False for this position). Will throw an exception if called and not implemented.
method EXISTS-POS($position) { ... }
Return Bool indicating whether the element at the given position exists (aka, is not marked as absent). If not implemented, Will call AT-POS and return True if the returned value is defined.
method CLEAR(--> Nil) { ... }
Reset the array to have no elements at all. By default implemented by repeatedly calling DELETE-POS, which will by all means, be very slow. So it is a good idea to implement this method yourself.
method move-indexes-up($up, $start = 0) { ... }
Add the given value to the indexes of the elements in the array, optionally starting from a given start index value (by default 0, so all elements of the array will be affected). This functionality is needed if you want to be able to use shift, unshift and related functions.
method move-indexes-down($down, $start = $down) { ... }
Subtract the given value to the indexes of the elements in the array, optionally starting from a given start index value (by default the same as the number to subtract, so that all elements of the array will be affected. This functionality is needed if you want to be able to use shift, unshift and related functions.
my $a = 42;
say is-container($a); # True
say is-container(42); # False
Returns whether the given argument is a container or not. This can be handy for situations where you want to also support binding, and allow for methods such as shift, unshift and related functions.
Elizabeth Mattijsen [email protected]
Source can be located at: https://github.com/lizmat/Array-Agnostic . Comments and Pull Requests are welcome.
Copyright 2018, 2020 Elizabeth Mattijsen
This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.