Stephen Hansen wrote:
On 6/30/10 11:58 PM, Jorgen Grahn wrote:
On Wed, 2010-06-30, Steven D'Aprano wrote:
On Wed, 30 Jun 2010 14:14:38 +0000, Jorgen Grahn wrote:
On Tue, 2010-06-29, Stephen Hansen wrote:
There's nothing silly about it.
It is an exaggeration though: but it does represent a good thing to
keep in mind.
Not an exaggeration: it's an absolute. It literally says that any time
you try to solve a problem with a regex, (A) it won't solve the
problem
and (B) it will in itself become a problem. And it doesn't tell you
why: you're supposed to accept or reject this without thinking.
It's a *two sentence* summary, not a reasoned and nuanced essay on the
pros and cons for REs.
Well, perhaps you cannot say anything useful about REs in general in
two sentences, and should use either more words, or not say anything
at all.
The way it was used in the quoted text above is one example of what I
mean. (Unless other details have been trimmed -- I can't check right
now.) If he meant to say "REs aren't really a good solution for this
kind of problem, even though they look tempting", then he should have
said that.
The way it is used above (Even with more stripping) is exactly where
it is legitimate.
Regular expressions are a powerful tool.
The use of a powerful tool when a simple tool is available that
achieves the same end is inappropriate, because power *always* has a
cost.
The entire point of the quote is that when you look at a problem, you
should *begin* from the position that a complex, powerful tool is not
what you need to solve it.
You should always begin from a position that a simple tool will
suffice to do what you need.
The quote does not deny the power of regular expressions; it
challenges widely held assumption and belief that comes from
*somewhere* that they are the best way to approach any problem that is
text related.
Does it come off as negative towards regular expressions? Certainly.
But not because of any fault of re's on their own, but because there
is this widespread perception that they are the swiss army knife that
can solve any problem by just flicking out the right little blade.
Its about redefining perception.
Regular expressions are not the go-to solution for anything to do with
text. Regular expressions are the tool you reach for when nothing else
will work.
Its not your first step; its your last (or, at least, one that happens
way later then most people come around expecting it to be).
Guys, this dogmatic discussion already took place in this list. Why
start again ?
Re is part of the python standard library, for some purpose I guess.
JM
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