Hey Levi,
TL:DR, if we can reserve some syntax for annotations that will be used by the PHP Engine, that would cover my concern. On 24 April 2016 at 17:57, Levi Morrison <le...@php.net> wrote: > isn't `@attr()` 100% valid user-land code today that can precede Er, yes it is! I didn't put too much thought the suggestion. The point I was trying to make is that it explicitly says that "this is a userland attribute", rather than using the generic <<...>> syntax, which we might want to use for non-userland attributes at some point. > how is @attr() different than `<<attr()>>`? If this RFC passes, someone could implement their own DBC feature using an annotation similar to: <<dbc($a + $b > 0, 'InvalidFooArgsException')>> Which under the current RFC proposal, would just be a standard annotation as far the PHP Engine is concerned. The framework/application the person is using would do the work to implement the DBC feature in userland code. In two years time when we want to implement dbc in the Engine, we would need to choose between either: * using <<dbc(...)>> as the syntax for the PHP internal feature, which would break userland code where they had chosen the same name we had. * using a different syntax to the <<...>> one to implement a DBC feature. * think up a cunning way of adding to the <<...>> syntax that doesn't break existing code that uses anotations. Choosing a syntax now that can be expanded for other uses in the future, is easier to do now, rather than in two years time, when it would be a BC break. Hack has implemented some 'special' attributes[1], that are interpreted by the HHVM Engine. All of those special attributes start with double underscores. If we did the same, and reserved (through documentation), that annotations starting with leading double underscores are reserved for future expansion, that would allow us to implement them (if we wanted to) without too many complaints of BC breakage. i.e. <<dbc(...)>> // this is a userland implementation <<__dbc(...)>> // Reserved for PHP internal implementation. cheers Dan [1] https://docs.hhvm.com/hack/attributes/special -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
