Class WP_User, methods add_cap/remove_cap are buggy

[mr.psiho]

Both methods use/make check in $this->caps, while capabilities are actually located in $this->allcaps. Therefore both these methods simply do not work at the moment.

[mr.psiho]

Ok, I got it! (spoiler: it was not obvious at all!) What I wanted to restrict user doing something. So, I just have to use it like this: $user->add_cap( 'read_post', false );