Multiton: Difference between revisions

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=={{header|Julia}}==

A registry (just in memory, not on disk) is used below instead of an enum. The registry is protected by a lock on the Multiton constructor, to prevent two threads creating the same object at the same time.

<~~lang~~ julia>struct Multiton{T}

<syntaxhighlight lang="julia">struct Multiton{T}

data::T

function Multiton(registry, refnum, data)

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# produce error

m5 = Multiton(reg, 5)

</~~lang~~>{{out}}

</syntaxhighlight>{{out}}

<pre>

Multiton is Multiton{String}("zero")

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=={{header|Perl}}==

<~~lang~~ perl># 20211215 Perl programming solution

<syntaxhighlight lang="perl"># 20211215 Perl programming solution

use strict;

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if ($inst0 eq $inst2) { print "Instance0 and Instance2 share the same object\n" };

if ($inst0 eq $inst3) { print "Instance0 and Instance3 share the same object\n" };

if ($inst3 eq $inst4) { print "Instance3 and Instance4 share the same object\n" };</~~lang~~>

if ($inst3 eq $inst4) { print "Instance3 and Instance4 share the same object\n" };</syntaxhighlight>

<pre>We create several instances and compare them to see if multiton is in effect.

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Put this (up to "end class") in a separate file, to keep allowed and instances private. Classes are not [yet] supported under pwa/p2js.

Technically I suppose this should really use new_dict()/getd()/setd(), but I'm quite sure you'll cope somehow..

without javascript_semantics

sequence allowed = {"zero","one","two"},

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?e.id

?f.id

<pre>

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=={{header|Raku}}==

Tried to translate [https://wikipedia.org/wiki/Multiton_pattern#Implementations the C# example] at WP but not sure if my interpretation/implementation is correct

<lang ~~perl6~~># 20211001 Raku programming solution

<syntaxhighlight lang="raku" line># 20211001 Raku programming solution

enum MultitonType < Gold Silver Bronze >;

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}

);

}</~~lang~~>

}</syntaxhighlight>

<pre>

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Although all Wren code runs within the context of a fiber (of which there can be thousands) only one fiber can run at a time and so the language is effectively single threaded. Thread-safety is therefore never an issue.

<~~lang~~ ecmascript>import "/dynamic" for Enum

<syntaxhighlight lang="ecmascript">import "/dynamic" for Enum

var MultitonType = Enum.create("MultitonType", ["zero", "one", "two"])

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System.print(m2)

var m3 = Multiton.getInstance(3) // produces an error</~~lang~~>

var m3 = Multiton.getInstance(3) // produces an error</syntaxhighlight>