Messages in this thread | | | Subject | Re: [PATCH] video/saa7164: Fix sparse warning: Using plain integer as NULL pointer | From | Andy Walls <> | Date | Tue, 25 Jan 2011 19:30:13 -0500 |
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On Tue, 2011-01-25 at 18:05 -0500, Devin Heitmueller wrote: > On Tue, Jan 25, 2011 at 5:54 PM, Peter Hüwe <PeterHuewe@gmx.de> wrote: > > Hi Julia, > > > > thanks for your input. > > So do I understand you correctly if I say > > if(!x) is better than if(x==NULL) in any case?
The machine code should be equivalent in size and speed.
> > Or only for the kmalloc family? > > > > Do you remember the reason why !x should be preferred? > > > > In Documentation/CodingStyle , Chapter 7: Centralized exiting of functions > > there is a function fun with looks like this: > > int fun(int a) > > { > > int result = 0; > > char *buffer = kmalloc(SIZE); > > > > if (buffer == NULL) > > return -ENOMEM;
> > > > --> So if (buffer == NULL) is in the official CodingStyle - maybe we should > > add a paragraph there as well ;)
CodingStyle shouldn't specify anything on the matter. There is no overall, optimal choice for all contexts. Arguing either way is as pointless as the Lilliputians' little-end vs. big-end dispute.
> To my knowledge, the current CodingStyle doesn't enforce a particular > standard in this regard, leaving it at the discretion of the author.
Correct, it does not. I just checked CodingStyle and checkpatch yesterday.
> Whether to do (!foo) or (foo == NULL) is one of those debates people > have similar to whether to use tabs as whitespace. People have > differing opinions and there is no clearly "right" answer.
It depends on one's measurement criteria for "optimizing" the written form of source code.
I prefer more explicit statement of action is taking place over statements with fewer characters. It usually saves me time when revisiting code.
More genrally I prefer any coding practice that saves me time when revisiting code. (Note the word "me" carries a lot of context with it.)
Ambiguity and implicit behaviors ultimately waste my time.
> Personally > I strongly prefer (foo == NULL) as it makes it blindingly obvious that > it's a pointer comparison, whereas (!foo) leaves you wondering whether > it's an integer or pointer comparison.
<usenet> Me too. </usenet>
> All that said, you shouldn't submit patches which arbitrarily change > from one format to the other. With regards to the proposed patch, you > should follow whatever style the author employed in the rest of the > file.
That is another reasonable critereon in "optimizing" the written form of the source code. I tend to give it less weight though.
Regards, Andy
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