Python in a Nutshell

Name

__new__ — Python 2.2 and later

Synopsis

__new__(cls[,args...])

When you call C ( [args...] ) and C is a new-style class, Python will obtain the new instance x that you are creating by invoking C .__new__( C,[args...] ). __new__ is a static method that every new-style class has (often simply inheriting it from object) and it can return any value x. In other words, __new__ is not constrained to returning a new instance of C, although normally it is expected to do so. If, and only if, the value x that __new__ returns is indeed an instance of C (whether a new or previously existing one), Python continues after calling __new__ by implicitly calling __init__ on x.