Question

I’d like to know if it’s a good idea avoid regex.

actually I have avoided it in any case and some peoples has been giving me advice that i shouldn’t avoid it, since if you know what means every thing like:

[] ‘|’ \A \B \d \D \W \w \S \Z $ * ? …

it would be easy to read, right? but i fell like avoiding regex i would have a more readable code.

it gets more unreadable when it’s bigger, example: validators.py

email_re = re.compile(
    r"(^[-!#$%&'*+/=?^_`{}|~0-9A-Z]+(\.[-!#$%&'*+/=?^_`{}|~0-9A-Z]+)*"  # dot-atom
    r'|^"([\001-\010\013\014\016-\037!#-\[\]-\177]|\\[\001-011\013\014\016-\177])*"' #     quoted-string
    r')@(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?$', re.IGNORECASE)  # domain

so, I’d like to know a reason to not avoid regex?

Answer 1

No, don’t avoid regular expressions. They’re actually quite a nifty little tool and will save you a lot of work if you use them wisely.

What you do need to avoid is trying to use it for everything, a malaise that appears to strike those new to regular expressions before they become a little more tempered and a little less enamoured 🙂

For example, don’t use it to validate email addresses. The way you validate an email address is to send an email to it with a link that the receiver has to click on to complete the “transaction”.

There are billions of valid email addresses (according to the RFCs) that have no physical email receiver behind them. The only way to be certain that there is a receiver is to send an email and wait for proof positive that it was received and acted upon.

If I find myself writing a regular expression that’s more than, let’s say, 60 characters, I step back to see if there’s a more readable way. Similarly, if I write a regular expression and come back a week later and can’t instantly recognise what it does, I think about replacing it. This particular paragraph consists of my opinions of course, but they’ve served me well 🙂