__call:
string(3) "ABC"
__call:
string(3) "ABC"
__call:
string(3) "xyz"
__call:
string(3) "www"

Deprecated: Use of "self" in callables is deprecated in %s on line %d
__call:
string(1) "y"

Deprecated: Use of "self" in callables is deprecated in %s on line %d
__call:
string(1) "y"
ok
call_user_func(): Argument #1 ($callback) must be a valid callback, class bar does not have a method "www"
call_user_func(): Argument #1 ($callback) must be a valid callback, cannot access "self" when no class scope is active