Issue 2948: unique_ptr does not define operator<< for stream output

Title: unique_ptr does not define operator<< for stream output
Status: c++20
Section: [unique.ptr]
Submitter: Peter Dimov

Created on 2017-03-19.00:00:00 last changed 56 months ago

Messages

Date: 2017-07-15.22:58:07

Proposed resolution:

This wording is relative to N4659.

Change [memory.syn], header <memory> synopsis, as indicated:

namespace std {
  […]
  
  // [unique.ptr], class template unique_ptr
  […]
  template <class T, class D>
  bool operator>=(nullptr_t, const unique_ptr<T, D>& y);
  
  template<class E, class T, class Y, class D>
  basic_ostream<E, T>& operator<< (basic_ostream<E, T>& os, const unique_ptr<Y, D>& p);
  […]
}

Change [unique.ptr], class template unique_ptr synopsis, as indicated:

namespace std {
  […]
  template <class T, class D>
  bool operator>=(nullptr_t, const unique_ptr<T, D>& y);
  
  template<class E, class T, class Y, class D>
  basic_ostream<E, T>& operator<< (basic_ostream<E, T>& os, const unique_ptr<Y, D>& p);
}

Add a new subclause following subclause [unique.ptr.special] as indicated:
23.11.1.?? unique_ptr I/O [unique.ptr.io]
```
template<class E, class T, class Y, class D>
  basic_ostream<E, T>& operator<< (basic_ostream<E, T>& os, const unique_ptr<Y, D>& p);
```
-?- Effects: Equivalent to os << p.get();
-?- Returns: os.
-?- Remarks: This function shall not participate in overload resolution unless os << p.get() is a valid expression.

msg9151 (view)

Date: 2017-07-15.22:58:07

[ 2017-07 Toronto Wed Issue Prioritization ]

Priority 0; move to Ready

msg9150 (view)

Date: 2017-03-19.00:00:00

shared_ptr does define operator<<, and unique_ptr should too, for consistency and usability reasons.

History
Date	User	Action	Args
2021-02-25 10:48:01	admin	set	status: wp -> c++20
2017-11-13 19:01:36	admin	set	status: voting -> wp
2017-10-17 18:34:55	admin	set	status: ready -> voting
2017-07-15 22:58:07	admin	set	messages: + msg9377
2017-07-15 22:58:07	admin	set	status: new -> ready
2017-04-22 14:21:01	admin	set	messages: + msg9151
2017-03-19 00:00:00	admin	create