Title
Defining an explicitly-specialized static data member
Status
cd2
Section
13.9.4 [temp.expl.spec]
Submitter
Daniel Krügler

Created on 2009-04-29.00:00:00 last changed 144 months ago

Messages

Date: 2009-10-15.00:00:00

[Voted into WP at October, 2009 meeting.]

Date: 2009-07-15.00:00:00

Proposed resolution (July, 2009):

Change 13.9.4 [temp.expl.spec] paragraphs 15-16 as follows:

An explicit specialization of a static data member of a template is a definition if the declaration includes an initializer; otherwise, it is a declaration. [Note: there is no syntax for the The definition of a static data member of a template that requires default initialization. must use a braced-init-list:

  template<> X Q<int>::x;      // declaration
  template<> X Q<int>::x ();   // error: declares a function
  template<> X Q<int>::x {};   // definition

This is a declaration regardless of whether X can be default initialized (9.4 [dcl.init]).end note]

Date: 2009-04-29.00:00:00

13.9.4 [temp.expl.spec] paragraphs 15-16 contain the following note:

[Note: there is no syntax for the definition of a static data member of a template that requires default initialization.
    template<> X Q<int>::x;
This is a declaration regardless of whether X can be default initialized (9.4 [dcl.init]). —end note]

While this note is still accurate, the C++0x list initialization syntax provides a way around the restriction, which could be useful if the class is not copyable or movable but has a default constructor. Perhaps the note should be updated to mention that possibility?

History
Date User Action Args
2010-03-29 00:00:00adminsetstatus: dr -> cd2
2009-11-08 00:00:00adminsetmessages: + msg2476
2009-11-08 00:00:00adminsetstatus: ready -> dr
2009-08-03 00:00:00adminsetmessages: + msg2178
2009-08-03 00:00:00adminsetstatus: open -> ready
2009-04-29 00:00:00admincreate