User-defined method objects may be created when getting an attribute of a class (perhaps via an instance of that class), if that attribute is a user-defined function object, an unbound user-defined method object, or a class method object.
class A(object): # func: A user-defined function object # # Note that func is a function object when it's defined, # and an unbound method object when it's retrieved. def func(self): pass # classMethod: A class method @classmethod def classMethod(self): pass class B(object): # unboundMeth: A unbound user-defined method object # # Parent.func is an unbound user-defined method object here, # because it's retrieved. unboundMeth = A.func a = A() b = B() print A.func # output: <unbound method A.func> print a.func # output: <bound method A.func of <__main__.A object at 0x10e9ab910>> print B.unboundMeth # output: <unbound method A.func> print b.unboundMeth # output: <unbound method A.func> print A.classMethod # output: <bound method type.classMethod of <class '__main__.A'>> print a.classMethod # output: <bound method type.classMethod of <class '__main__.A'>>
When the attribute is a user-defined method object, a new method object is only created if the class from which it is being retrieved is the same as, or a derived class of, the class stored in the original method object; otherwise, the original method object is used as it is.
# Parent: The class stored in the original method object class Parent(object): # func: The underlying function of original method object def func(self): pass func2 = func # Child: A derived class of Parent class Child(Parent): func = Parent.func # AnotherClass: A different class, neither subclasses nor subclassed class AnotherClass(object): func = Parent.func print Parent.func is Parent.func # False, new object created print Parent.func2 is Parent.func2 # False, new object created print Child.func is Child.func # False, new object created print AnotherClass.func is AnotherClass.func # True, original object used
The following is an example of using an user-defined function to be called multiple(∞) times in a script with ease.
import turtle, time, random #tell python we need 3 different modules turtle.speed(0) #set draw speed to the fastest turtle.colormode(255) #special colormode turtle.pensize(4) #size of the lines that will be drawn def triangle(size): #This is our own function, in the parenthesis is a variable we have defined that will be used in THIS FUNCTION ONLY. This fucntion creates a right triangle turtle.forward(size) #to begin this function we go forward, the amount to go forward by is the variable size turtle.right(90) #turn right by 90 degree turtle.forward(size) #go forward, again with variable turtle.right(135) #turn right again turtle.forward(size * 1.5) #close the triangle. thanks to the Pythagorean theorem we know that this line must be 1.5 times longer than the other two(if they are equal) while(1): #INFINITE LOOP turtle.setpos(random.randint(-200, 200), random.randint(-200, 200)) #set the draw point to a random (x,y) position turtle.pencolor(random.randint(1, 255), random.randint(1, 255), random.randint(1, 255)) #randomize the RGB color triangle(random.randint(5, 55)) #use our function, because it has only one variable we can simply put a value in the parenthesis. The value that will be sent will be random between 5 - 55, end the end it really just changes ow big the triangle is. turtle.pencolor(random.randint(1, 255), random.randint(1, 255), random.randint(1, 255)) #randomize color again