Called by the repr() built-in function and by string conversions (reverse quotes) to compute the “official” string representation of an object. If at all possible, this should look like a valid Python expression that could be used to recreate an object with the same value (given an appropriate environment). If this is not possible, a string of the form <...some useful description...> should be returned. The return value must be a string object. If a class defines __repr__() but not __str__(), then __repr__() is also used when an “informal” string representation of instances of tha...
Called to create a new instance of class cls. __new__() is a static method (special-cased so you need not declare it as such) that takes the class of which an instance was requested as its first argument. The remaining arguments are those passed to the object constructor expression (the call to the class). The return value of __new__() should be the new object instance (usually an instance of cls).
Typical implementations create a new instance of the class by invoking the superclass’s __new__() method using super(currentclass, cls).__new__(cls[,...]) with appropriate arguments and then modif...
Called when the instance is created. The arguments are those passed to the class constructor expression. If a base class has an__init__() method, the derived class’s __init__() method, if any, must explicitly call it to ensure proper initialization of the base class part of the instance; for example: BaseClass.__init__(self, [args...]). As a special constraint on constructors, no value may be returned; doing so will cause a TypeError to be raised at runtime.
__init__ method could be overriden in two ways: old way is to call __init__ directly from parent class and new way use super. Let's look in...
Called when the instance is “called” as a function; if this method is defined, x(arg1, arg2, ...) is a shorthand for x.__call__(arg1, arg2,...).
>>> x = Foo()
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/IPython/core/interactiveshell.py", line 2731, in run_code
exec code_obj in self.user_global_ns, self.user_ns
File "<ipython-input-168-7354d77c61ac>", line 1, in <module>
AttributeError: Foo instance has no __call__ method