Object-oriented programming in Python simple summary 3--custom classes

Statement: Resources from the MU-class network Python Learning course, the following is only a summary of individual learning, for reference only

Special methods for 1.Python classes

Features: Methods that begin and end with __ , such as __str__ () for print, __getattr__ (), __setattr__ (), etc.

There is no need to call directly in code, and some Python functions and operators are called automatically.

You can customize the implementation, such as the __str__ () method

classPerson (object):def __init__(self,name,gender): Self.name=name Self.gender=Genderdef __str__(self):return '(Person:%s,%s)'%(Self.name,self.gender)PrintPerson ("Roger","Male")

Python defines the __str__ () and __repr__ () two methods, which are displayed to the user, which is displayed to the developer, so if __str__ () is modified under the interactive command line, then the call may not be modified but the __repr__ () is called. You can also make the same two methods: __repr__ = __str__

2. Special Setter and Getter

In Python, the setter and getter can be written by the adorner, making the call more straightforward, and, of course, using Java in a similar way. Because Python supports higher-order functions, the Get/set method can be decorated with adorners as attributes.

classStudent (object):def __init__(self, Name, score): Self.name=name self.__score=score @property#Decorate Get method    defscore (self):returnSelf.__score@score. Setter#Decorative Set method, a byproduct of @property decoration    defscore (self, score):ifScore < 0orScore > 100:            RaiseValueError ('Invalid score') self.__score=score#after decorating, you can set the score as you would with the propertiess = Student ("Bob", 59) S.score= 60PrintS.scores.score= 1000PrintS.score#There will be exceptions, because the scope of the score is checked.

3. Restrict the properties that the current class can have: __slots__

class Student (object):     __slots__ = ('name''gender'Score  ')    def__init__(self, name, gender, score):        = name        = gender        = Score

4. Callable objects (objects can also be called)

In Python, a function is an object, called a callable object, and an instance of a class can become a callable object, just to implement a special method __call__()

class Person (object):     def __init__ (self,name,gender):         = name        = gender    def__call__(self, *args, **kwargs):   # Implement the __call__ method so that the instance can be called        print args

class Fib (object):     def __call__ (self, num):         = 0, 1, []        for in  Range (num):            l.append (a)            = B, A + b        
    return= Fib ()print f (10)

Object-oriented programming in Python simple summary 3--custom classes