Re: Proposal for serious BC compatibility aka language versioning

On Sun, Feb 3, 2013 at 12:36 PM, Karoly Negyesi <karoly@negyesi.net> wrote: > Hi, > > So, if we are talking about PHP 6, then the opening <?php tag should be > accompanied by the version it was written for, it was tested with and then > the engine could switch to a compatibility mode for that version. > > Seems to me that this would solve the problem where a host can't upgrade to > a more modern version for fear of breaking old code. Consequently, open > source packages -- like Drupal I am deeply involved with -- can't use more > modern PHP versions decreasing the "push" for hosts to upgrade. This is a > devilish circle and it'd be great to break it. > > Regards, > > Karoly Negyesi > At least two points why this makes no sense whatsoever: 1) One would have to maintain or at least keep around all previous versions of the engine and the libraries. That would be a shitload of cruft and a lot of maintenance work. 2) Different behavior per-file is not feasible as components in both files interact. If you have one <?php6 file and one <?php5 file and both interact (like, you know, calling a function from one file in the other one) you will have a pretty hard time decided what behavior this should result in. The <?php6 behavior or the <?php5 one? So something like this can only be done on a per-request basis (rather than per-file). And to do this on a per-request basis you already have all the means. Just run two different PHP versions. No issue with that; doesn't require no further support from PHP. Nikita