David Abrahams wrote:
"Fernando Cacciola" <fernando_cacciola@hotmail.com> writes:
So the only choices I see are:
o.rebind(rb)
or
o = optional<T&>(rb).
And I think I like the rebind() better.
One more reason to keep the latter: don't you want to be able to put optional's in std::containers? I think it's important that they be proper values; disabling assignment altogether would be bad, and I don't think I want optional<T&>'s assignment operator to deep-copy the T.
Oh, I wasn't thinking at all on disabling copy assignment. That will definitely stay. But since you need to spell the contained type to use copy assignment I was considering _additional_ methods that can make the assignment syntactically easier. A member fuction like rebind() is one alternative, but yes, there is the problem that it makes little sense with non-rerefence types. I suggested to add: make_optional(v); as a shortcut for: optional<some_type>(v). People argued, with reason, that you still need to discriminate yourself references from non-references (so you would need to use a different shortcut, like, make_optional_ref(r)) But actually I don't think having to discriminate that explicitely is much of a probem. So my current proposal would be: Remove direct-assignment. Let copy-assigment be the only way to define the wrapped value Add make_optional() and make_optional_ref() as shorcuts to help with copy-assignment Keep none-assignment as the only wat to clear the wrapped value. -- Fernando Cacciola SciSoft http://fcacciola.50webs.com/