Singleton: Difference between revisions

=={{header|Ecstasy}}==

The <code>static</code> keyword in a class declaration will compile that class as a singleton. It is legal to define <code>const</code> (i.e. immutable) and <code>service</code> classes as singletons. Modules, packages, and enumeration values are always singleton classes. It is <b>not</b> legal to define normal <code>class</code> classes as singletons, because normal classes are mutable, and Ecstasy does not allow shared mutable state.

The name of the class is used to specify that singleton instance:

<syntaxhighlight lang="ecstasy">

module test {

static service Singleton {

private Int counter;

String fooHasBeenCalled() {

return $"{++counter} times";

}

}

void run() {

@Inject Console console;

for (Int i : 1..5) {

console.print($"{Singleton.fooHasBeenCalled()=}");

}

}

}

</syntaxhighlight>

{{out}}

<pre>

x$ xec test

Singleton.fooHasBeenCalled()=1 times

Singleton.fooHasBeenCalled()=2 times

Singleton.fooHasBeenCalled()=3 times

Singleton.fooHasBeenCalled()=4 times

Singleton.fooHasBeenCalled()=5 times

</pre>