> On Tue, Apr 16, 2013 at 11:34:52PM +0000, YAMAMOTO Takashi wrote: >> > On Tue, Apr 16, 2013 at 11:39:50PM +0900, Takehiko NOZAKI wrote: >> >> so that the struct _locale __C_locale in libc is much more wasteful. >> > >> > I should add that it is an internal detail and the way the composed C >> > locale is stored can and likely will change later. So the way it is >> > essentially a copy of (old) global locale is just a way to be minimally >> > intrusive. >> > >> > Joerg >> >> i care the API. >> >> if you really want it be in libc, how about having libc provide a >> "locale_t get_static_c_locale();" style API rather than using NULL? >> it's better because 1) less code in *_l, 2) autoconf-like can detect >> the extension easily, and 3) a portable application can trivially >> have a fallback implementation using newlocale+pthread_once. > > It adds more cost on the caller side. So far, there are three mechanisms > available (especially for libraries): > > (1) Adhoc access to internal locale state. This is used with glibc. > (2) Explicit newlocale(). > (3) Implicit access via 0 argument to *_l. > > The first one is clearly a hack and not acceptable. Portable code can > always conditionally use (2), but it requires additional setup and > storage cost. (3) is used by Apple (which is where a large part of the > *_l interface originates from) and FreeBSD. It is orthogonal to (2) and > certainly easier to use. Exposing it via a special library call is also > possible and effectively a way to implement (2) by a static wrapper. > It still adds more cost to every caller and this is a classic case where > there are typically much more callers. > > Joerg
(3) adds small costs to every calls of *_l, even when the extension is not used. i sounds worse than a one-time cost of (2) to me. YAMAMOTO Takashi
