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Function std.experimental.checkedint.Checked.opUnary

Defines unary operators +, -, ~, ++, and --. Unary + is not overridable and always has built-in behavior (returns this). For the others, if Hook defines hookOpUnary, opUnary forwards to Checked!(typeof(hook.hookOpUnary!op(get)), Hook)(hook.hookOpUnary!op(get)).

auto opUnary(string op, _)()
if (op == "+" || op == "-" || op == "~");

ref Checked opUnary(string op)()
if (op == "++" || op == "--");

If Hook does not define hookOpUnary but defines onOverflow, opUnary forwards to hook.onOverflow!op(get) in case an overflow occurs. For ++ and --, the payload is assigned from the result of the call to onOverflow.

Note that unary - is considered to overflow if T is a signed integral of 32 or 64 bits and is equal to the most negative value. This is because that value has no positive negation.

Example

static struct MyHook
{
    static bool thereWereErrors;
    static L hookOpUnary(string x, L)(L lhs)
    {
        if (x == "-" && lhs == -lhs) thereWereErrors = true;
        return -lhs;
    }
}
auto a = checked!MyHook(long.min);
writeln(a); // -a
assert(MyHook.thereWereErrors);
auto b = checked!void(42);
writeln(++b); // 43

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