On Sat, 06 Dec 2008 14:15:28 -0500, Roy Smith wrote:
> In article <[EMAIL PROTECTED]>,
> Steven D'Aprano <[EMAIL PROTECTED]> wrote:
>
>> On Sat, 06 Dec 2008 08:50:20 -0500, Roy Smith wrote:
>>
>> > For your first
>> > project, pick something that's small enough that you think you could
>> > tackle it in under 50 lines of Perl.
>>
>> Is there anything which *can't* be written in under 50 lines of Perl?
> [...]
>> Also, Perl REs are faster than Python REs, or so I'm told. Between the
>> speed and the convenience, Perl programmers tend to use RE's for
>> everything they can. Python programmers tend to use REs only for
>> problems that *should* be solved with REs rather than *can* be solved
>> with a RE.
>
> Well, as an old-time unix hacker (who learned REs long before Perl
> existed), my question to you would be, "Is there any problem which
> *shouldn't* be solved with an RE?" :-)
I think you've answered your own question:
> One of the reasons REs don't get used in Python as much as in Perl is
> because strings have useful methods like startswith(), endswith(), and
> split(), and also the "in" operator. These combine to give you easy
> ways to do many things you might otherwise do with REs.
Also:
* splitting pathnames and file extensions
* dealing with arbitrarily nested parentheses
* any time you need a full-blown parser (e.g. parsing HTML or XML)
* sanitizing untrusted user input
("I bet I can think of *every* bad input and detect them all
with this regex!")
* validating email addresses
http://northernplanets.blogspot.com/2007/03/how-not-to-validate-email-addresses.html
* testing prime numbers
http://jtauber.com/blog/2007/03/18/python_primality_regex/
* doing maths
http://blog.stevenlevithan.com/archives/algebra-with-regexes
http://weblogs.asp.net/rosherove/archive/2004/11/08/253992.aspx
There's probably more.
--
Steven
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