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Function `object.require`

Looks up key; if it exists returns corresponding value else evaluates value, adds it to the associative array and returns it.


						
				ref V require(K, V)
				(
				

				  ref V[K] aa,
				

				  K key,
				

				  lazy V value = V.init
				

				);

Parameters

Name	Description
aa	The associative array.
key	The key.
value	The required value.

Returns

The value.

Example

auto aa = ["k1": 1];
writeln(aa.require("k1", 0)); // 1
writeln(aa.require("k2", 0)); // 0
writeln(aa["k2"]); // 0
}

// Tests whether T can be @safe-ly copied. Use a union to exclude destructor from the test.
private enum bool isSafeCopyable(T) = is(typeof(() @safe { union U { T x; } T *x; auto u = U(*x);

Authors

Walter Bright, Sean Kelly

License

Boost License 1.0.