Classmethod In Python Code Example

Example 1: class methods in python

from datetime import date  # random Person class Person:     def __init__(self, name, age):         self.name = name         self.age = age      @classmethod     def fromBirthYear(cls, name, birthYear):         return cls(name, date.today().year - birthYear)      def display(self):         print(self.name + "'s age is: " + str(self.age))  person = Person('Adam', 19) person.display()  person1 = Person.fromBirthYear('John',  1985) person1.display()

Example 2: python: @classmethod

class Float:     def __init__(self, amount):         self.amount = amount      def __repr__(self):         return f'<Float {self.amount:.3f}>'      @classmethod     def from_sum(cls, value_1, value_2):         return cls(value_1 + value_2)   class Dollar(Float):     def __init__(self, amount):         super().__init__(amount)         self.symbol = '€'      def __repr__(self):         return f'<Euro {self.symbol}{self.amount:.2f}>'   print(Dollar.from_sum(1.34653, 2.49573))

Example 3: class methods parameters python

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

Example 4: class methods in python

@classmethod def func(cls, args...)

Example 5: python classmethod

class point: 	def __init__(self, x, y):     	self.x = x         self.y = y              @classmethod     def zero(cls):     	return cls(0, 0)              def print(self):     	print(f"x: {self.x}, y: {self.y}")          p1 = point(1, 2) p2 = point().zero() print(p1.print()) print(p2.print())

Example 6: python classmethod

# classmethod example In [20]: class MyClass:     ...:     @classmethod     ...:     def set_att(cls, value):     ...:         cls.att = value     ...:  In [21]: MyClass.set_att(1)  In [22]: MyClass.att Out[22]: 1  In [23]: obj = MyClass()  In [24]: obj.att Out[24]: 1  In [25]: obj.set_att(3)  In [26]: obj.att Out[26]: 3  In [27]: MyClass.att Out[27]: 3