I vaguely remember I saw somewhere a discussion on this but I cannot find it now; "non-const min max c++" and similar variants give no relevant results.
Why doesn't the C++ standard library include the following non-const overload of
std::min (and similarly for
template <typename T> T& min(T& a, T& b);
It could be useful sometimes, e.g. if I want to increase the lower number:
std::min(x, y) += 1;
Are there any problems this overload would cause?
In the same discussion Howard mentions these as the reasons for the rejection:
The implementation was considered too complicated at the time. Though I haven’t tried, it could almost surely be done much more simply in today’s language/library. At the very least what is called “promote” in the implementation is today called “std::common_type”.
Part of the complication is that I attempted to solve several problems at the same time:
- Being able to assign into the result of min (but only when safe to do so).
- Eliminate dangling reference dangers at compile-time.
- Support heterogeneous integral comparisons, weeding out dangerous combinations at compile-time.
- Support move-only types.
As T.C. mentions in the same discussion, a proposal would also need to not break code such as:
int i = 1; std::min(i, 0);
If you're interested in solving the problems mentioned in the discussion and writing a proposal + example implementation, then this could eventually make it into the Standard.