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Function `object.assumeSafeAppend`

Assume that it is safe to append to this array. Appends made to this array after calling this function may append in place, even if the array was a slice of a larger array to begin with.


						
				auto ref inout(T[]) assumeSafeAppend(T)
				(
				

				  auto ref inout(T[]) arr
				

				) nothrow @system;

Use this only when it is certain there are no elements in use beyond the array in the memory block. If there are, those elements will be overwritten by appending to this array.

Warning

Calling this function, and then using references to data located after the given array results in undefined behavior.

Returns

The input is returned.

Example

int[] a = [1, 2, 3, 4];

// Without assumeSafeAppend. Appending relocates.
int[] b = a [0 .. 3];
b ~= 5;
assert(a.ptr != b.ptr);

debug(SENTINEL) {} else
{
    // With assumeSafeAppend. Appending overwrites.
    int[] c = a [0 .. 3];
    c.assumeSafeAppend() ~= 5;
    writeln(a.ptr); // c.ptr
}

Authors

Walter Bright, Sean Kelly

License

Boost License 1.0.