5.3 stops getting security fixes in August. Deprecations first, then the behaviour changes, then the version bump — and an APC replacement that ignores every setting you tuned.
An optional collaborator — a logger only configured in production, a cache that may be switched off, a discount that may not apply — produces the same three…
Setter injection and a service locator both let a class acquire a collaborator at the moment it happens to need one, so nothing about the class announces how…