Messages in this thread | | | Date | Mon, 14 Apr 2008 13:52:59 +0200 | From | "Hans J. Koch" <> | Subject | Re: [PATCH] Re: [PATCH 4/4 v2] [RFC] UIO: generic platform driver |
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On Mon, Apr 14, 2008 at 12:37:59PM +0100, Russell King - ARM Linux wrote: > On Mon, Apr 14, 2008 at 01:20:21PM +0200, Uwe Kleine-König wrote: > > [1] http://lkml.org/lkml/2008/4/11/81 or > > http://thread.gmane.org/gmane.linux.kernel/665257 > > In one of the mails, it was said: > No. It's more important to see which variables are declared in the > function and which are declared elsewhere. If you have to search the > whole body of a function for possible declarations, this is BAD. And if > it's not clear where a variable is used, the function is too long or has > other style problems. Your function is short and clean, so where's the > problem? Please move the declaration to the top of the function. > > I disagree with this statement. It's far better to limit the scope of > variables so that you know they only have local use, and eg, not used > inside a loop and then outside with possible unintended effects. > > If a variable is only used inside a loop, it should be declared _inside_ > that loop. > > The statement goes on to talk about the function being short and clean - > that's not an argument to apply any particular point of view on this > subject, since you can argue that because it's short and clean you can > see that the variable is only used within the loop. > > So, please, keep the variable declaration inside the loop, and don't > pollute the outer levels with unnecessary variable declarations.
OK, I'm finally convinced :-) I knew this style from C++ where it makes sense, because a (class-) variable declaration can implicitly call the constructor of that class which you normally want to avoid if not needed. As this doesn't happen in C, I found it unnecessary. I agree now that there's also a readability argument. The limitation of the scope is probably not that important as compilers will optimize that anyway in a lot of cases.
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