Re: [PRE-RFC] PREG_THROW_ON_ERROR flag

On Tue, Jul 7, 2026 at 4:17 AM Osama Aldemeery <aldemeery@gmail.com> wrote: > Hi all, > > I'd like to propose adding a PREG_THROW_ON_ERROR flag to > the preg_*() > functions, and gauge interest in that. > > Json and ext/filter both grew an opt-in way to turn a silent > error into > an exception...that is JSON_THROW_ON_ERROR and > FILTER_THROW_ON_FAILURE. > PCRE is the one left out where a failing call is easy to miss. An > execution error for example (e.g. a bad UTF-8) surfaces only if > you call preg_last_error() afterwards, and a malformed pattern > emits a > warning and returns false. > > PREG_THROW_ON_ERROR would do for PCRE what those two do for > their > functions. > Passing it to any preg_*() call makes a PCRE error throw a > Pcre\PcreException that carries the > PREG_*_ERROR code and the > preg_last_error_msg() text > instead of warning or returning > false/null. > And it covers both kinds: a compilation error (e.g. a malformed pattern) > and an execution error, so opting in means any PCRE failure becomes a > single catchable exception. > Also, preg_replace() and > preg_filter() gain an optional > $flags > parameter to accept it (the only two without one as far as I know). > > Concretely, the check you'd write today: > > ``` > if (preg_match($pattern, $subject, $m) === false) { > throw new RuntimeException(preg_last_error_msg()); > } > ``` > > ...collapses to: > > ``` > preg_match($pattern, $subject, $m, PREG_THROW_ON_ERROR); > ``` > > First, I'd like to know whether there's interest at all and whether anyone > sees a reason not to add it. > > If there is interest, a couple of design questions I'd want the list's > read on: > > 1. Array subjcets. Currently preg_last_error() reflects only > the > last element processed, but I'd have the flag throw on the first > failing element rather than keep last-one-wins...does that seem right? > 2. Whether *_ON_ERROR reads better than > *_ON_FAILURE given the > existing > preg_last_error()/PREG_*_ERROR > vocabulary. > > If it seems worth pursuing, I'll write it up as a proper RFC. > > Thanks, > Osama > Hi all, I've put together a complete implementation across all the preg_*() functions so I can open a PR if it helps the discussion. For now I've got it throwing on the first failing element for arrays, and went with PREG_THROW_ON_ERROR for the flag name, just so I could complete the implementation. Still eager to hear what people have to say about that though, and to know whether there's interest/objection before I take it further. Thanks, Osama