class Foo (object):
# ^class name #^ inherits from object
bar = "Bar" #Class attribute.
def __init__(self):
# #^ The first variable is the class instance in methods.
# # This is called "self" by convention, but could be any name you want.
#^ double underscore (dunder) methods are usually special. This one
# gets called immediately after a new instance is created.
self.variable = "Foo" #instance attribute.
print self.variable, self.bar #<---self.bar references class attribute
self.bar = " Bar is now Baz" #<---self.bar is now an instance attribute
print self.variable, self.bar
def method(self, arg1, arg2):
#This method has arguments. You would call it like this: instance.method(1, 2)
print "in method (args):", arg1, arg2
print "in method (attributes):", self.variable, self.bar
a = Foo() # this calls __init__ (indirectly), output:
# Foo bar
# Foo Bar is now Baz
print a.variable # Foo
a.variable = "bar"
a.method(1, 2) # output:
# in method (args): 1 2
# in method (attributes): bar Bar is now Baz
Foo.method(a, 1, 2) #<--- Same as a.method(1, 2). This makes it a little more explicit what the argument "self" actually is.
class Bar(object):
def __init__(self, arg):
self.arg = arg
self.Foo = Foo()
b = Bar(a)
b.arg.variable = "something"
print a.variable # something
print b.Foo.variable # Foo