Singleton: Difference between revisions

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~~{{task|Object oriented}}A Global Singleton is a class of which only one instance exists within a program.~~ Any attempt to use non-static members of the class involves performing operations on this one instance.

A Global Singleton is a class of which only one instance exists within a program.

⚫

Any attempt to use non-static members of the class involves performing operations on this one instance.

=={{header|ActionScript}}==

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x.wait ; y.wait ; z.wait ;

}</lang>

Sample Output:

<pre>>>Mary come in.

Calling Dealer...

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}

}</lang>

Output:

<pre>invoking method of a singleton class</pre>

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</lang>

'''output'''

main____________:0000000001:@035a8767|-

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(dm message2> ()

(prinl "This is method 2 on " This) )</lang>

Output:

<pre>: (message1> '+Singleton)

This is method 1 on +Singleton

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=={{header|Slate}}==

Clones of Oddball themselves may not be cloned. ~~Methods and slots may still be defined on them:~~

Clones of Oddball themselves may not be cloned.

Methods and slots may still be defined on them:

<lang slate>define: #Singleton &builder: [Oddball clone]</lang>

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}

}</lang>

Demonstrating in an interactive shell

Demonstrating in an interactive shell:

<lang tcl>% set a [example new]

::oo::Obj20

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=={{header|zkl}}==

A class declared static only has one instance, ever. ~~However, a class with the same name & structure could be created in another scope.~~

A class declared static only has one instance, ever.

However, a class with the same name & structure could be created in another scope.

<lang zkl>class [static] Borg{ var v }

b1 := Borg; b2 := Borg();