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### 138. Class `ctype_byname<char>` redundant and misleading

Section: 30.4.2.5 [locale.codecvt] Status: NAD Submitter: Angelika Langer Opened: 1999-03-18 Last modified: 2016-01-28

Priority: Not Prioritized

View all other issues in [locale.codecvt].

View all issues with NAD status.

Discussion:

Section 30.4.2.5 [locale.codecvt] specifies that `ctype_byname<char>` must be a specialization of the `ctype_byname` template.

It is common practice in the standard that specializations of class templates are only mentioned where the interface of the specialization deviates from the interface of the template that it is a specialization of. Otherwise, the fact whether or not a required instantiation is an actual instantiation or a specialization is left open as an implementation detail.

Clause 22.2.1.4 deviates from that practice and for that reason is misleading. The fact, that `ctype_byname<char>` is specified as a specialization suggests that there must be something "special" about it, but it has the exact same interface as the `ctype_byname` template. Clause 22.2.1.4 does not have any explanatory value, is at best redundant, at worst misleading - unless I am missing anything.

Naturally, an implementation will most likely implement `ctype_byname<char>` as a specialization, because the base class `ctype<char>` is a specialization with an interface different from the `ctype` template, but that's an implementation detail and need not be mentioned in the standard.

[ Summit: ]

> Reopened by Alisdair.

[ 2009-07 Frankfurt ]

> Moved to NAD.

Rationale:

The standard as written is mildly misleading, but the correct fix is to deal with the underlying problem in the `ctype_byname` base class, not in the specialization. See issue 228.