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Re: Redundant return()

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On 05/15/2012 06:24 PM, Ian Collins wrote:
> On 05/16/12 09:58 AM, BartC wrote:
>> "James Kuyper"<jameskuyper@verizon.net>  wrote in message
>> news:jotj8p$2j5$1@dont-email.me...
...
>>> The relevant issue isn't speed, but ease of comprehension. Supporters of
>>> "single exit" claim it's easier to comprehend; my personal experience is
>>> that early-return is easier.
>>
>> Yes. Easier in that there is then a choice.
>>
>> I can't see the problem with multiple returns. No matter how many returns
>> there are in one function, the next statement executed will always be the
>> one falling the original call. That's not much different from 'single exit'.
> 
> Clean-up is always the elephant in the room with multiple returns in C. 
>   Hence the proliferation of goto spaghetti.  I for one prefer early 
> return on precondition tests, but once a function allocates a resource 
> or changes a state, there should only be one.

I'm in perfect agreement here. If I allocate memory, I normally use the
following structure where possible (there's obviously situations in
which it's NOT possible):

retval = SUCCESS;

p = malloc(count * sizeof *p);
if (p == NULL)
{
    // error handling
    return ERROR1;
}
else
{
    // Normal processing. 'return' prohibited in this block.

    if(error condition)
    {
        // other error handling
        retval = ERROR2;
    }

    free(p);
}

return retval;


I handle fopen() and fclose() similarly, and any other similar book-end
functions (the libraries I use have quite a few book-end pairs).

This approach doesn't scale well when many different resources need to
be managed simultaneously, in which case more complicated approaches are
needed.

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Redundant return() pembed2012 <once@was.enough.invalid> - 2012-05-12 21:41 +0000
  Re: Redundant return() pembed2012 <once@was.enough.invalid> - 2012-05-12 21:56 +0000
    Re: Redundant return() Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2012-05-12 17:07 -0600
  Re: Redundant return() James Kuyper <jameskuyper@verizon.net> - 2012-05-12 18:46 -0400
    Re: Redundant return() Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-05-12 20:10 -0400
      Re: Redundant return() James Kuyper <jameskuyper@verizon.net> - 2012-05-12 21:29 -0400
  Re: Redundant return() Barry Schwarz <schwarzb@dqel.com> - 2012-05-12 15:49 -0700
    Re: Redundant return() pembed2012 <once@was.enough.invalid> - 2012-05-14 16:40 +0000
      Re: Redundant return() Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-05-14 17:57 +0100
      Re: Redundant return() nick_keighley_nospam@hotmail.com - 2012-05-15 00:33 -0700
        Re: Redundant return() nick_keighley_nospam@hotmail.com - 2012-05-15 03:03 -0700
          Re: Redundant return() nick_keighley_nospam@hotmail.com - 2012-05-15 03:26 -0700
          Re: Redundant return() James Kuyper <jameskuyper@verizon.net> - 2012-05-15 08:51 -0400
        Re: Redundant return() "BartC" <bc@freeuk.com> - 2012-05-15 12:20 +0100
          Re: Redundant return() Ian Collins <ian-news@hotmail.com> - 2012-05-16 07:59 +1200
            Re: Redundant return() Kaz Kylheku <kaz@kylheku.com> - 2012-05-15 20:08 +0000
              Re: Redundant return() Ian Collins <ian-news@hotmail.com> - 2012-05-16 08:18 +1200
                Re: Redundant return() Lanarcam <lanarcam1@yahoo.fr> - 2012-05-15 22:48 +0200
                Re: Redundant return() Ian Collins <ian-news@hotmail.com> - 2012-05-16 09:56 +1200
            Re: Redundant return() "BartC" <bc@freeuk.com> - 2012-05-15 22:59 +0100
              Re: Redundant return() Ian Collins <ian-news@hotmail.com> - 2012-05-16 10:16 +1200
                Re: Redundant return() "BartC" <bc@freeuk.com> - 2012-05-16 09:29 +0100
        Re: Redundant return() Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-05-15 07:51 -0400
        Re: Redundant return() James Kuyper <jameskuyper@verizon.net> - 2012-05-15 08:47 -0400
          Re: Redundant return() Ian Collins <ian-news@hotmail.com> - 2012-05-16 08:01 +1200
          Re: Redundant return() "BartC" <bc@freeuk.com> - 2012-05-15 22:58 +0100
            Re: Redundant return() Ian Collins <ian-news@hotmail.com> - 2012-05-16 10:24 +1200
              Re: Redundant return() James Kuyper <jameskuyper@verizon.net> - 2012-05-15 18:39 -0400
              Re: Redundant return() nick_keighley_nospam@hotmail.com - 2012-05-16 02:45 -0700
  Re: Redundant return() Noob <root@127.0.0.1> - 2012-05-16 13:34 +0200

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