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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
Copyright © 1999-2022 by the D Language Foundation | Page generated by ddox.