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Re: Favourite Pattern for Processing Zero, Once, Multiple

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Shao Miller <sha0.miller@gmail.com> wrote:

> Suppose you have a function 'bar' that returns a value that means one of:
>   - Do 'foo' zero times
>   - Do 'foo' one time
>   - Do 'foo' more than one time
 
> What's your favourite way of handling such a value?  

It isn't very C-like to do it that way.

Since C doesn't allow multiple entry points to a function
(like Fortran or PL/I ENTRY statement) it is usual to have one function
do both jobs.

Note, for example, the C strtok() function.

With strtok, on the first call you pass the string to tokenize,
on subsequent calls you pass NULL. (It does keep state in static
storage, and so can't be used in reentrant code.)

In the zero case, strtok() returns NULL on the first call,
for the one time case, NULL on the second call, and more than
one, on the N+1th call. 

So, why do you special case the 0 and 1 case? 

If you really need that, loop through counting the number of
times the function returns non-NULL, then start over with
the appropriate choice. 

Also, note for example, the Java Iterator class.

-- glen

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Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-10 17:53 -0500
  Re: Favourite Pattern for Processing Zero, Once, Multiple "BartC" <bc@freeuk.com> - 2013-01-10 23:26 +0000
    Re: Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-10 18:49 -0500
      Re: Favourite Pattern for Processing Zero, Once, Multiple "BartC" <bc@freeuk.com> - 2013-01-11 00:23 +0000
  Re: Favourite Pattern for Processing Zero, Once, Multiple Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-11 03:20 +0000
    Re: Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-11 00:38 -0500
      Re: Favourite Pattern for Processing Zero, Once, Multiple Bart van Ingen Schenau <bart@ingen.ddns.info.invalid> - 2013-01-11 12:10 +0000
        Re: Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-11 13:37 -0500
      Re: Favourite Pattern for Processing Zero, Once, Multiple "BartC" <bc@freeuk.com> - 2013-01-11 12:15 +0000
        Re: Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-11 13:56 -0500
          Re: Favourite Pattern for Processing Zero, Once, Multiple Fred K <fred.l.kleinschmidt@gmail.com> - 2013-01-11 11:15 -0800
            Re: Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-11 14:28 -0500
          Re: Favourite Pattern for Processing Zero, Once, Multiple Greg Martin <greg@softsprocket.com> - 2013-01-11 11:22 -0800
            Re: Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-11 15:23 -0500
              Re: Favourite Pattern for Processing Zero, Once, Multiple Greg Martin <greg@softsprocket.com> - 2013-01-11 13:09 -0800
          Re: Favourite Pattern for Processing Zero, Once, Multiple "BartC" <bc@freeuk.com> - 2013-01-11 22:09 +0000
          Re: Favourite Pattern for Processing Zero, Once, Multiple Paul N <gw7rib@aol.com> - 2013-01-12 04:49 -0800
            Re: Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-13 20:30 -0500
  Re: Favourite Pattern for Processing Zero, Once, Multiple glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-11 21:02 +0000
  Re: Favourite Pattern for Processing Zero, Once, Multiple Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2013-01-13 20:28 +0200
    Re: Favourite Pattern for Processing Zero, Once, Multiple Shao Miller <sha0.miller@gmail.com> - 2013-01-13 16:12 -0500

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