Re: [PATCH v2] Make fetch-pack a builtin with an internal API

From: Theodore Tso <tytso@mit.edu>
Date: Jul 9, 2007, 14:40 UTC
Message-ID: <20070709144030.GE16032@thunk.org>
In-Reply-To: <200707091416.39949.andyparkins@gmail.com>

On Mon, Jul 09, 2007 at 02:16:35PM +0100, Andy Parkins wrote:

Show 13 quoted lines

> 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.

Show 5 quoted lines

> 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