Re: string-match bug?

["Andreas Röhler" <andreas.roehler@easy-emacs.de>]

Barry Margolin wrote:
> In article <mailman.12469.1260221021.2239.help-gnu-emacs@gnu.org>,
>  Matthew Dempsky <matthew@dempsky.org> wrote:
> 
>> On Mon, Dec 7, 2009 at 12:37 PM, Andreas Röhler
>> <andreas.roehler@easy-emacs.de> wrote:
>>> Why should questioned string respond here it contains an empty string at 
>>> position 0?
>>> Makes no sense for me.
>> Here's an analogy: (string-match "xyzzy" "fooxyzzybar") returns 3.
>> This is because the first 5 characters starting at position 3 are
>> "xyzzy", the same as the first string parameter.  The significance of
>> 5 here is the length of "xyzzy".
>>
>> Similarly, (string-match "" "foo") returns 0.  This is because the
>> first 0 characters starting at position are "", the same as the first
>> string parameter.
> 
> Here's another example of a limit case:
> 
> (string-match "a*" "b") returns 0, because a* matches zero or more a's, 
> and there are zero a's at position 0.
> 

Hmm, interesting

IMHO that differs:

(string-match "a*" "b") asks for a non-occurrence too. So "0" of first position is plausible.

If asked for non-occurrence of empty, no problem:

The meaning of "" reverted, ie asked for the first occurence of any non-empty string, "0" would be ok also.

Still pretending: the empty string can't match any non-empty string, at no position...

Thanks all

Andreas