[RFC] Abstract final classes

Hi, I worked on an implementation of a somehow controversial concept that exists in hack and C#: abstract final classes. https://wiki.php.net/rfc/abstract_final_class My motivation is to further expand class support to add modifiers (PPP - public, protected, private). I added this change to initially segregate grammar rules. It was an easy feature without extensive complexity and covers some use-cases. As a reference, here is the commit hash that added this feature to Hack: https://github.com/facebook/hhvm/commit/faedfaf46b0deb859b0c20fb36a574be7a4f2f55 Cheers, -- Guilherme Blanco MSN: guilhermeblanco@hotmail.com GTalk: guilhermeblanco Toronto - ON/Canada