파이썬 매직 메서드 호출방법

Some of the magic methods in Python directly map to built-in functions; in this case, how to invoke them is fairly obvious. However, in other cases, the invocation is far less obvious. This appendix is devoted to exposing non-obvious syntax that leads to magic methods getting called.

 

 

Magic Method	When it gets invoked(example)	Explanation
__new__(cls [,...])	instance = MyClass(arg1, arg2)	__new__ is called on instance creation
__init__(self [,...])	instance = MyClass(arg1, arg2)	__init__ is called on instance creation
__cmp__(self, other)	self == other, self > other, etc.	Called for any comparison
__pos__(self)	+self	Unary plus sign
__neg__(self)	-self	Unary minus sign
__invert__(self)	~self	Bitwise inversion
__index__(self)	x[self]	Conversion when object is used as index
__nonzero__(self)	bool(self)	Boolean value of the object
__getattr__(self, name)	self.name # name doesn't exist	Accessing nonexistent attribute
__setattr__(self, name, val)	self.name = val	Assigning to an attribute
__delattr__(self, name)	del self.name	Deleting an attribute
__getattribute__(self, name)	self.name	Accessing any attribute
__getitem__(self, key)	self[key]	Accessing an item using an index
__setitem__(self, key, val)	self[key] = val	Assigning to an item using an index
__delitem__(self, key)	del self[key]	Deleting an item using an index
__iter__(self)	for x in self	Iteration
__contains__(self, value)	value in self, value not in self	Membership tests using in
__call__(self [,...])	self(args)	"Calling" an instance
__enter__(self)	with self as x:	with statement context managers
__exit__(self, exc, val, trace)	with self as x:	with statement context managers
__getstate__(self)	pickle.dump(pkl_file, self)	Pickling
__setstate__(self)	data = pickle.load(pkl_file)	Pickling