Messages in this thread | | | Date | Mon, 25 Jul 2005 16:13:13 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [patch 2.6.13-rc3] i386: clean up user_mode macros |
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On Mon, 25 Jul 2005, Chuck Ebbert wrote: > > Recent patches from the Xen group changed the X86 user_mode macros. > > This patch does the following: > > 1. Makes the new user_mode() return 0 or 1 (same as x86_64)
I _really_ prefer
x != 0
over
!!x
since double negation is not only a bad habit in natural languages, it's a bad habit in computer languages too, for exactly the same reason. It's confusing.
Ask a hundred random C programmers what "!!x" means, versus what "x != 0" means, and time their replies.
I will bet you $5 USD that even if they all give the right answer (and I suspect you'll get a few wrogn answers in there too for the !! case), they'll take a _lot_ longer answering the "!!x" version than they will the "x != 0" question.
And guess what? That means that the "!!x" version is worse. It means that people don't "see" what it means - they have to think about it. And you shouldn't have to think about something like that, you should write it in the obvious way in the first place.
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