Re: [boost] [optional] using name boost::in_place -- need your opinion/advice

30 May 2016


      2016-05-30 13:21 GMT+02:00 Krzysztof Czainski <1czajnik@gmail.com>:
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2016-05-30 12:46 GMT+02:00 Andrey Semashev :
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2016-05-30 11:29 GMT+02:00 Andrey Semashev
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The typed in-place
factories ruin the solution though, even if not used by
On Monday, 30 May 2016 13:45:28 MSK Krzysztof Czainski
wrote:
optional.
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How so?
Typed in-place factory requires an explicit template parameter
to be specified, which is not achievable if in_place is an object.
Oh yeah. Too bad a variable template cannot be "overloaded" with the
non-template function object.
Maybe in_place can be hacked as is without changing it to a function
object? Here's a proof of concept. It compiles [1], so it seems 'in_place'
can be used as a tag with the current implementation of boost::in_place()
overloads.

[1] http://ideone.com/zzbwq4


   1. struct in_place_factory0 {};
   2.
   3. in_place_factory0 in_place() {}
   4. template <class T> void in_place(T) {}
   5. template  void in_place(T, U) {}
   6.
   7. void test(in_place_factory0 (&in_place_tag)()) {}
   8.
   9. int main() {
   10. test(in_place);
   11. }