I've heard that the regex API has changed quite a bit between 5.10 and 5.12 due to the promotion of regexes to first class objects. If that's true, one should either just target 5.12 or newer when writing a new plugin, or be aware of the differences and use some #ifdefs.
I wonder if any of these are in use and what are the use cases? What issues do these plugs solve that is impossible, harder, slower or have some other issues with the standard regex engine of Perl?
The now deceased re::engine::TRE had two features that made it attractive for some uses: for one it would match the longest of several alternations (instead of the first, as Perl does), and secondly it uses a non-backtracking state machine internally whenever possible, which means that pathological exponential time behavior doesn't occur as easily as with the Perl engine.
