Bind can't use `boost::result_of`

[denzor200]

I discovered that boost::bind strongly requires to have result_type meta-field from the type of the passed functional object. I was surprised, because why not to use boost::result_of when possible? Can we fix it, even it will be a breaking change?

The shortest-reproducible example here: https://godbolt.org/z/5fhb1hdYa

[pdimov]

boost::bind predates result_of and was never updated to support it. As result_of is obsolete nowadays, if we're going to change boost::bind, we should make it use decltype directly.

That's not an entirely trivial change though, because currently objects returned by boost::bind have a fixed return type, exposed via ::result_type.

[denzor200]

we should make it use decltype directly.

You suggest to raise up minimal standard version to C++11 here? If so, what will be a reason to use boost::bind instead of std::bind? I thought this library is a C++03 analogue of C++11's std::bind

[denzor200]

Or you just want to say that boost::bind is obsolete and there is no sense to resolve this issue?

[pdimov]

You suggest to raise up minimal standard version to C++11 here?

On this specific instance I was thinking of using decltype when available, and retaining the current behavior when not.

If so, what will be a reason to use boost::bind instead of std::bind? I thought this library is a C++03 analogue of C++11's std::bind

boost::bind actually predates std::bind and is the source of the std::bind proposal. Much code still uses it so it would still make sense to keep it working even if we drop C++03, and it has some features that std::bind lacks, such as operators and some other subtle differences.

Or you just want to say that boost::bind is obsolete and there is no sense to resolve this issue?

boost::bind by itself may not be entirely obsolete, but I wouldn't invest much in new development targeting C++03.