Re: yet another pattern-matching library for Lua

[Philippe Lhoste <PhiLho@...>]

Paul Smith a écrit :
> I think the main problem people have is that they are difficult to read 
> 'at a glance'. Once you realise that they are often quite comprehensible 
> once you start breaking them down, they become a lot easier, but a lot 
> of people will look at them, and because they don't understand it 
> immediately, the little switch that says 'I can't do this' trips, and 
> they will say that regexps are hard and they can't do them without 
> actually trying.

Exactly! Using the x mode (with line breaks, comments and indentation) 
can be useful too with complex expressions like:
^((0[1-9]|1\d|2[0-8])/(0\d|1[012])/(1[6-9]|[2-9]\d)\d{2}|(29|30)/(0[13-9]|1[012])/(1[6-9]|[2-9]\d)\d{2}|31/(0[13578]|1[02])/(1[6-9]|[2-9]\d)\d{2}|29/02/((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|(16|[2468][048]|[3579][26])00))$

> If people were introduced to regexps by things like
>
> gr[ea]y
>
> rather than
>
> \b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b
>
> they'd probably find them a lot easier... I think the difficulty is 
> mainly a mind-set one rather than actual difficulty.

Exactly. Tired of seeing tutorial matching aaaacbbb, useful only for 
people parsing DNA sequences :-), I made my own tutorial trying to use 
real-world example and only previously seen concepts (no forward 
references).
For the curious-minded and critical eyes, it is at:
http://Phi.Lho.free.fr/programming/RETutorial.en.html
Private mails for remarks, it is off topic...

--
Philippe Lhoste
--  (near) Paris -- France
--  http://Phi.Lho.free.fr
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