According to http://php.net/manual/en/migration55.deprecated.php:
The preg_replace() /e modifier is now deprecated. Instead, use the preg_replace_callback() function.
I don’t think I’ve ever used it but what does \e do and why would they deprecate it?
Good question. I’ve never used it either.
AFAIK it has to do with making back referencing more “elegant”. My regex has gotten quite gnarly at times but not to the point where it got all that bad. Then again, I often don’t learn about things until I actually absolutely need to.
/e was a modifier to a pattern that PHP-Evaluated on the backreferences in a pattern. As you can imagine, such a thing was… sketchy to use at the best of times, and a downright security hole many other times. The number of uses for it would be incredibly small, and should be handled by other functions or in a better way.
Great, thanks.