On Wed, 13 Jun 2007, Grant Likely wrote: > On 6/13/07, Alan Stern <[EMAIL PROTECTED]> wrote: > > On Wed, 13 Jun 2007, Grant Likely wrote: > > > > > On 6/12/07, Peter Korsgaard <[EMAIL PROTECTED]> wrote: > > > > >>>>> "Grant" == Grant Likely <[EMAIL PROTECTED]> writes: > > > > > > > > Hi, > > > > > > > > Grant> Rather than c67x00-hub.c being compiled seperately, the > > > > Grant> original code had c67x00-hub.c *included* by c67x00-hcd.c. > > > > Grant> This is a very bad idea. > > > > What's so bad about it? It's an elegant solution to the problem of > > breaking a very long driver up into smaller, more digestible pieces > > without polluting the kernel's namespace with lots of extra global > > symbols. > > Primarily because it breaks convention. Convention is that you > #include .h files, and you compile and link .c files. Convention is > important because it reflects the common patterns we use when reading > and writing (but mostly reading) code.
The problem is that there are conflicting conventions. You mentioned one. But there's another: .h files contain declarations and things that should be shared among multiple source files, and .c files contain things that generate object code (executable routines, static definitions, and so on). The idea is that sharing something which generates object code would be a mistake, since every source file which included it would generate a copy of those same objects. So if you want to #include a file which generates object code, one convention says it should be named .h and the other says it should be named .c. A possible solution would be to use yet a different suffix, but I think that would only make matters worse. (Just to add to the confusion, some people feel that .c files shouldn't include much that _doesn't_ generate object code. Hence they put top-level declarations in a .h file, even though it is #included in only one .c file. This is mainly a matter of taste...) > Yes there are exceptions, and yes it can be done, but there better be > a damn good reason for doing so. In this particular case, I really > don't think it is warranted. The reason for doing it is the second convention. IMO that's just as good a reason for doing it as the first convention is for not doing it. > We're not talking about a great deal of > code, and we're *already* polluting the kernel namespace with c67x00_* > function names because the driver is already in multiple pieces. Sorry, I don't know what you mean. How does the fact that uhci-hcd is in multiple pieces create names like c67x00_*? Besides, the fact that we are already doing it doesn't justify unnecessarily doing even more. > This issue has also come up on the LKML also. See this thread: > > http://thread.gmane.org/gmane.linux.kernel/498633 I read that thread some time ago. If you look at it carefully, you'll find that Linus is arguing in favor of the second convention -- mine, not yours. > > What's so ugly about breaking a driver up into pieces? Leaving it in > > one giant piece would be much more ugly IMO. > > Breaking into pieces: Good, and I fully agree. > Doing it in non-standard way: Not so good as it trades one kind of > ugliness for another. But what should one do when there are two conflicting standards? Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
