linux-kernel - Re: [PATCH] linux/string.h: Introduce streq macro.

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Message-ID: <878vuvuk6l.fsf@rustcorp.com.au>
Date:	Thu, 28 Apr 2011 13:00:26 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	"H. Peter Anvin" <hpa@...or.com>,
	Steven Rostedt <rostedt@...dmis.org>
Cc:	Thiago Farina <tfransosi@...il.com>, linux-kernel@...r.kernel.org,
	Alexey Dobriyan <adobriyan@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	"David S. Miller" <davem@...emloft.net>,
	Al Viro <viro@...iv.linux.org.uk>, Ted Ts'o <tytso@....edu>,
	Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH] linux/string.h: Introduce streq macro.

On Wed, 27 Apr 2011 11:33:07 -0700, "H. Peter Anvin" <hpa@...or.com> wrote:
> On 04/27/2011 10:49 AM, Steven Rostedt wrote:
> > On Tue, 2011-04-26 at 16:45 -0300, Thiago Farina wrote:
> >> This macro is arguably more readable than its variants:
> >> - !strcmp(a, b)
> >> - strcmp(a, b) == 0
> > 
> > Actually, this was proposed way back in 2002 my Rusty and I did not see
> > anyone arguing against it. I wonder why it never was incorporated back
> > then?
> > 
> > http://marc.info/?l=linux-kernel&m=103284339813100&w=2
> > 
> > [ added Cc's of some of those that replied to this thread ]
> > 
> 
> Because !strcmp() is idiomatic C.

I proposed it because I *did* find a bug caused by my own misuse of it.
Only once in 15 years as an experienced C coder, but a bug is a bug.

But why argue; #define it in your code if you want.  If enough people
do, we'll want to unify it.

Personally, I think it's marginal: only those with enough knowledge to
avoid the trap anyway will know to use it, and YA kernel-specific piece
of knowledge cancels the readability benefit.

But who knows, maybe it'll catch on elsewhere too?  That would be a win.

> It doesn't matter if it is more readable *to you*... learn the language,
> please.

That API is crap: insulting the user makes us look foolish.

And even experienced coders can get hit by bad APIs.  The invalidity of
this program shocked me recently:

  #include <ctype.h>
  int main(int argc, char *argv[]) { return isupper(argv[0][0]) ? 1 : 0; }

Thanks,
Rusty.
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