Re: Alternatives for encapsulation when using composition instead of inheritance

2021-08-26 20:30 GMT+02:00, Rowan Tommins <rowan.collins@gmail.com>: > On 26/08/2021 14:47, Olle Härstedt wrote: >> Don't know if this already exists, but maybe we could consider >> brainstorming or gather alternatives for different types of >> encapsulation when using composition? > > > Although not quite equivalent to your suggestions, these threads on > making delegation to an encapsulated object might be interesting to you: > > * https://externals.io/message/103353 > * https://github.com/php/php-src/pull/5168 Right, there are indeed a bunch of attempts and suggestions, some downvoted, others abandoned. I'm thinking adding namespaces to runtime might be a logical first step. That would allow attributes to add logic like internal properties for a certain namespace. Makes me wonder why that never happened for this PR: https://github.com/php/php-src/pull/947 Asking anyone on the list, would it be possible to make an opcode out of "namespace Foo\Bar" and letting it set a flag in the runtime system when run? Then make the flag accessible with a constant like __NAMESPACE_RUNTIME__ or whatever. Ooooh, there's an interesting case with "goto" and namespace visibility here: https://github.com/php/php-src/pull/947#issuecomment-419821198 That would mean every zval has to carry in which namespace it was defined inside. I wonder how that would affect the memory footprint of PHP. > If we had something like that, then perhaps there could be a > "delegatable" visibility, which was the equivalent for "protected", but > when delegating rather than inheriting, e.g. > > class Foo { > private int $a = 1; > delegatable int $b = 2; > } > > class Bar { > private delegate Foo $foo; > public function __construct(Foo $foo) { > $this->foo = $foo; > echo $this->a; // Error: can't access private property of a > different class > echo $this->b; // allowed: access is to a "delegatable" > property, in a "delegated" context > } > } The Foo class has to decide who to give access to, otherwise it's the same as public access. Olle