Class-named services cannot be used for hooks

[aschempp]

Due to the class_exists check in System::importStatic (and System::import) it is not possible to register a hook listener service if the class name is used as service name. Do we really need that class_exists check?

[Toflar]

Nope, container->has() is enough. +1 for dropping that (as a bugfix!).

[leofeyer]

We have added the check to prevent services from accidentally overwriting existing classes, which would then no longer be loaded. So no, $container->has() is not enough.

[discordier]

@leofeyer This won't work for native Symfony 3.3 applications anymore as the suggested service name IS the class name.
See here and here

So in the end you will have to alias an symfony service to something else to make it usable in Contao then?
I'm all up for using only $container->has().

[aschempp]

I think the only and major issue we had initially was with our Session class and Symfony's session. Because System::import('Session') would take the service instead of our class. So we gotta make sure about that …

[aschempp]

I think the best approach is to check for a backslash in the name.

if ($container->has($name) && (false !== strpos($name, '\') || !class_exist($name)) {
}

[leofeyer]

Fixed in 9361ea9.