Negation in regular expressions

[Steve Holden]

George Sakkis wrote:
> It's always striked me as odd that you can express negation of a single
> character in regexps, but not any more complex expression. Is there a
> general way around this shortcoming ? Here's an example to illustrate a
> use case:
> 
> 
>>>>import re
> 
> # split with '@' as delimiter
> 
>>>>[g.group() for g in re.finditer('[^@]+', 'This @ is a @ test ')]
> 
> ['This ', ' is a ', ' test ']
> 
> Is it possible to use finditer to split the string if the delimiter was
> more than one char long (say 'XYZ') ? [yes, I'm aware of re.split, but
> that's not the point; this is just an example. Besides re.split returns
> a list, not an iterator]
> 
I think you are looking for "negative lookahead assertions". See the docs.

regards
  Steve
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