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Document number: N4126

Date: 2014-07-29

Explicitly defaulted comparison operators

by Oleg Smolsky

Excerpt:

N3950 was presented to the Evolution WG at the Rapperswil meeting and the response was very positive. A later revision, N4114 was amended to handle the following points requested at the meeting:

• Support for non-member operators
• Mutable members: there was consensus on their treatment. The compromise is to to make explicitly defaulted operators ill-formed when mutable members are present. See "Mutable members".
• Short-hand notation was proposed and had very positive feedback. See "The proposed syntax: short form".

This proposal makes the following changes after the technical review on the c++std-ext list:

• Pointer, floating point and enumerated type members are included. See "Domain of the operator functions" for the discussion.
• Each explicitly defaulted operator is independent and is bridged to the respective members' operators
• Lexicographical comparison is defined explicitly