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### 2028. `messages_base::catalog` overspecified

Section: 28.4.8.2 [locale.messages] Status: C++14 Submitter: Howard Hinnant Opened: 2011-02-14 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

In 28.4.8.2 [locale.messages], `messages_base::catalog` is specified to be a typedef to `int`. This type is subsequently used to open, access and close catalogs.

However, an OS may have catalog/messaging services that are indexed and managed by types other than `int`. For example `POSIX`, publishes the following messaging API:

>     typedef unspecified nl_catd;

>     nl_catd catopen(const char* name , int oflag);
>     char*   catgets(nl_catd catd, int set_id, int msg_id, const char* s);
>     int     catclose(nl_catd catd);

I.e., the catalog is managed with an unspecified type, not necessarily an `int`. Mac OS uses a `void*` for `nl_catd` (which is conforming to the `POSIX` standard). The current `messages_base` spec effectively outlaws using the built-in OS messaging service supplied for this very purpose!

[2011-02-24: Chris Jefferson updates the proposed wording, changing unspecified to unspecified signed integral type]

[2011-03-02: Daniel updates the proposed wording, changing unspecified signed integral type to unspecified signed integer type (We don't want to allow for `bool` or `char`)]

[2011-03-24 Madrid meeting]

Consensus that this resolution is the direction we would like to see.

Proposed resolution:

1. Modify 28.4.8.2 [locale.messages]:

   >     namespace std {
   >       class messages_base {
   >       public:
   >         typedef intunspecified signed integer type catalog;
   >       };
   >       ...
   >     }