[hnriot]

Didn't you just make the previous commenters point, that regex implementations vary? Within those three there are variations too with the flags and how they implement word boundaries (either exclusion of word characters or inclusion of certain spacing chars)

[jessedhillon]

I think the case that there are too many implementations is overstated. Almost everyone can get away with knowing only PCRE these days. Most programmers I've know don't even know that they're using PCRE, they just know they're using "regexes"

[saraid216]

I haven't had the incentive to learn regexes well enough to understand why I have to escape random things in different languages and environments. And occasionally something will fail to work all my cases and I have to fall back on a non-regex way of matching.

I've generally found that my practice is basically "try regex; if it doesn't work after ten minutes of effort, abandon regex completely".