On Mon, Jul 09, 2007 at 02:16:35PM +0100, Andy Parkins wrote:
> On Monday 2007 July 09, Theodore Tso wrote:
> > On Sun, Jul 08, 2007 at 10:39:41PM -0700, Junio C Hamano wrote:
> > > Are _identifiers with leading underscore Kosher thing to do, I
> > > wonder... We do have ones with trailing ones (mostly qsort
> > > functions) and I think they are done that way for the sake of
> > > standards conformance.
> >
> > _[a-z]* is kosher for file scopes or function scoping:
>
> Perhaps I'm reading it wrong but:
>
> "All identifiers beginning with an underscore are reserved for ordinary
> identifiers (functions, variables, typedefs, enumeration constants) with file
^^^^^^^^^
> scope."
^^^^^^
>
> Doesn't agree with what you've said. I think that you _can_ use _[a-z]* for
> labels or structure members - however, not within file or function scope.
I think the above does agree with what I said. It says that you can
use functions, variables, typdefs, enumeration constants (not just
labels or structure members) WITH FILE SCOPE. I.e., so long as it
doesn't leak across a .o linkage. So one .o file can use a static
_my_strdup, and another .o file can use a static _my_strdup, and they
don't have to worry about multiply defined function conflicts, since
they are static functions with file or smaller scoping.
And if it's safe to use a file-level static scoping, then obviously it
would be safe to use a function-level static scoping.
> However, the rule of thumb I've always used is "don't start identifiers with
> underscore". I can't think of a situation that would mean you have to use an
> underscore to start an identifier - so why get into detailed worries about
> where it's allowed and where it isn't. Just don't use it. The document you
> linked to gives exactly this advice:
Yep, this is the safer thing to do if you don't want to remember the
more complicated rule. But it's not *necessary*; no system library
will use a single underscore followed by a lower-case letter, since
that's reserved for programs for local file-level scoping. A system
library will use for its private function identifiers that begin
either a double underscore, or a underscore followed by an uppercase
latter.
Regards,
- Ted
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