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copied!<p>The code examples in this answer assume the following declaration:</p> <pre><code>var implementation: MyInterface; </code></pre> <h3>Providing an implementation of a callable interface</h3> <p>As a follow-up to <a href="https://stackoverflow.com/a/12770145/238753">the accepted answer</a>, as suggested by some of its commentors, a function that matches the interface's call signature implicitly implements the interface. So you can use any matching function as an implementation.</p> <p>For example:</p> <pre><code>implementation = () => "Hello"; </code></pre> <p>You don't need to explicitly specify that the function implements the interface. However, if you want to be explicit, you can use a cast:</p> <pre><code>implementation = <MyInterface>() => "Hello"; </code></pre> <h3>Providing a reusable implementation</h3> <p>If you want to produce a reusable implementation of the interface like you normally would with a Java or C# interface, just store the function somewhere accessible to its consumers.</p> <p>For example:</p> <pre><code>function Greet() { return "Hello"; } implementation = Greet; </code></pre> <h3>Providing a parameterised implementation</h3> <p>You may want to be able to parameterise the implementation in the same way that you might parameterise a class. Here's one way to do this:</p> <pre><code>function MakeGreeter(greeting: string) { return () => greeting; } implementation = MakeGreeter("Hello"); </code></pre> <p>If you want the result to be typed as the interface, just explicitly set the return type or cast the value being returned.</p>

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