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A polyfill for using fb_intercept across hhvm 3.24 -> 4.present

v2.0.1 2021-10-27 19:47 UTC


A polyfill for using fb_intercept across hhvm 3.24 -> 4.present

Why you don't need this polyfill. The polyfill bridges the gap between a hhvm that understands inout without being in the transition period for &$references and one that doesn't understand &$references. The HH\Lib\Ref<T> is a class does not require runtime support, so it can be used as a mediator. If your hhvm is not in the transition period for &$references, but it does have HH\Lib\Ref<T> support, you may want to use this polyfill.


fb_intercept() is a built-in function. This gives it the superpower that it can't be intercepted itself. The polyfill is userland code, so it can be intercepted. Therefore you can't use the catchall interceptor key '' (empty string), since you would be intercepting calls to the polyfill itself. This makes it impossible to call fb_intercept() after that. The polyfill will throw if you pass it the catchall key, telling you that this is not supported. If you intercept the polyfill by name intentionally, you'll not be able to restore it. So don't do that. 😉

Installation instructions for library authors

Version v1.x.x and v2.x.x will retain API intercompatibility as a promise. v1 will only run on hhvm 4.28 and below and v2 will only run on 4.20 and up. The public API has not changed, only the hhvm version requirement and some implementation details.

We therefore STRONGLY advice that your version constraint for this library is "^1|^2". This is required to be installable on all hhvm versions.

Users of this library who do not intend to run on older hhvm versions can set a "^2" constraint, but the "^1|^2" constraint would also work for you.