Re^3: $/ is playing havoc with my script.

[sauoq]

Well, if that's what he actually recommends, I'll politely ignore his recommendation. Most of the time you don't need /s or /m. They're useless if you aren't working with multi-line strings. If you are working with multi-line strings, then you may very well want either the behavior you get with them or without them. In that case, you really should know exactly what you are trying to do and use them or not as is fitting, not because you read a book that said use them by default. IMHO, of course.

[chester]

I think it's not so much a matter of "not knowing what you're doing", as wanting the regex engine to be consistent in that one symbol always means one thing.

If you use /ms all the time, then \A always means "beginning of the string", ^ means "beginning of a line", \z means "end of the string", $ means "end of a line, . means "any character", and [^\n] means "any character but a newline".

You lose no functionality, and you gain the benefit of consistency (and possibly intuitiveness, depending on your intuition). You also partially eliminate what the Apocalypse calls the "end-weight problem", which I assume means that you have no idea what your regex is doing until you scan all the way to the end to see the modifiers. Whether this is really a problem is debatable, and you still have i and g (etc.) to grapple with in any case.

Of course you also lose a bit of conciseness, which is a minus. It's just a question of style. TMTOWTDI

[sauoq]

You lose no functionality, and you gain the benefit of consistency (and possibly intuitiveness, depending on your intuition).

Consistency isn't exactly a hallmark of Perl. (Take context as an example. Or the wide variety of behavior you get from builtins. Or the whole philosophy of TMTOWTDI.) The tradeoff it often makes is consistency for flexibility. Perl's flexibility makes it great! But, it pushes the burden of consistency off to us, the developers.

And, it's partially in the interest of consistency that I would reject the advice to use /msx all the time because I expect that the great volume of Perl code written so far does not follow that advice. I'm also fairly certain that I'm not the only one who has seen [^\n] in someone's regex and suggested that using a lone dot would be more Perlish.

The more practical reason, however, is that when I see /m or /s or \A or \Z these are strong visual cues that immediately indicate the data a given regex is dealing with probably has embedded newlines. I'd really rather not give that up.