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Re: Casting function pointers to different signatures

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On 04/23/2015 06:49 PM, samuelallenalexander@gmail.com wrote:
> On Thursday, April 23, 2015 at 11:04:53 PM UTC+1, James Kuyper wrote:
>> On 04/23/2015 05:39 PM, Sam wrote:
...
>>> Thanks for the very detailed answer with references and everything.
>>>
>>> It's really too bad the behavior is undefined since it would open the door for porting some genuinely useful OOP/FP idioms into C.
>>
>> How is the door closed? It's trivial to make the function types
>> compatible, and if you do, the code will work. Could you give an example
>> of code using one of those idioms where it's excessively difficult to
>> avoid the problem? Your current example does NOT qualify.
> 
> Yes, you could make the individual printer functions have signature
> void (*) (void*), but that makes those individual printer functions a
> lot more opaque on their own, and it's very repetitive that you have
> to repeat the casts over and over.

That comment suggests a possible misunderstanding. If the function types
were, in fact, compatible, there would be no need for a cast, the
function would already have the correct type.

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Casting function pointers to different signatures samuelallenalexander@gmail.com - 2015-04-23 13:39 -0700
  Re: Casting function pointers to different signatures Barry Schwarz <schwarzb@dqel.com> - 2015-04-23 14:01 -0700
  Re: Casting function pointers to different signatures James Kuyper <jameskuyper@verizon.net> - 2015-04-23 17:10 -0400
    Re: Casting function pointers to different signatures samuelallenalexander@gmail.com - 2015-04-23 14:39 -0700
      Re: Casting function pointers to different signatures James Kuyper <jameskuyper@verizon.net> - 2015-04-23 18:04 -0400
        Re: Casting function pointers to different signatures samuelallenalexander@gmail.com - 2015-04-23 15:49 -0700
          Re: Casting function pointers to different signatures James Kuyper <jameskuyper@verizon.net> - 2015-04-23 19:22 -0400
            Re: Casting function pointers to different signatures samuelallenalexander@gmail.com - 2015-04-24 10:42 -0700
              Re: Casting function pointers to different signatures James Kuyper <jameskuyper@verizon.net> - 2015-04-24 14:18 -0400
                Re: Casting function pointers to different signatures samuelallenalexander@gmail.com - 2015-04-24 12:36 -0700
                Re: Casting function pointers to different signatures James Kuyper <jameskuyper@verizon.net> - 2015-04-24 15:50 -0400
                Re: Casting function pointers to different signatures Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-24 13:18 -0700
    Re: Casting function pointers to different signatures Siri Cruz <chine.bleu@yahoo.com> - 2015-04-23 16:08 -0700
      Re: Casting function pointers to different signatures Keith Thompson <kst-u@mib.org> - 2015-04-23 18:36 -0700
        Re: Casting function pointers to different signatures Siri Cruz <chine.bleu@yahoo.com> - 2015-04-23 19:00 -0700
          Re: Casting function pointers to different signatures raltbos@xs4all.nl (Richard Bos) - 2015-04-25 10:48 +0000
      Re: Casting function pointers to different signatures Tim Rentsch <txr@alumni.caltech.edu> - 2015-04-25 04:05 -0700
  Re: Casting function pointers to different signatures Lőrinczy Zsigmond <nospam@for.me> - 2015-04-24 06:51 +0200
  Re: Casting function pointers to different signatures Richard Damon <Richard@Damon-Family.org> - 2015-04-25 10:57 -0400

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