Inheritance of the python-class

1. Simple inheritance

class F1:  # parent class, or base class    def  Show (self):        print('  F1.show')class F2 (F1):  # indicates F2 inherits F1. F2 is called a subclass, or a derived class    def  bar (self        ):print('bar '  = F2 () obj.show () Obj.bar ()

Out

F1.show
Bar

2. The parent class and subclass have the same method, and the methods in the subclass are taken precedence

classF1:#parent class, or base class    defShow (self):Print('F1.show')classF2 (F1):#represents the F2 inheritance F1. F2 called subclasses, or derived classes    defBar (self):Print('Bar')    defShow (self):#sub-class priority high        Print('F2.show') obj=F2 () obj.show () Obj.bar ( )

Out

F2.show
Bar

3. Encapsulates data in subclasses, and can also be accessed in the parent class

classF1:#parent class, or base class    defShow (self):Print('F1.show')    deffoo (self):Print(Self.name)classF2 (F1):#represents the F2 inheritance F1. F2 called subclasses, or derived classes    def __init__(self,name): Self.name=namedefBar (self):Print('Bar') obj= F2 ('xiaoming') Obj.foo ()#The output is xiaoming, and inheritance is equivalent to putting the parent class's method into the subclass, so the output here is Xiaoming

Out

4. Complex inheritance

classS1:defF1 (self): self. F2 ()#the self at this point corresponds to the object obj    defF2 (self):Print('S1.f2')classS2 (S1):defF3 (self): self. F1 ()defF2 (self):Print('S2.f2') obj=S2 () obj. F3 ()#The output is s2.f2, the execution process: executes the self when executing the F3 method in the S2 class. F1 () method, because there is no method in S2, so go to the parent class to look for, the parent class has the method,#then the F1 () method in the parent class is executed, and self is executed when the F1 () method is executed. F2 (). Because the essence of inheritance is to copy the method of the parent class into the subclass,#So Def F1 (self): self. F2 () is placed in the S2 class because there is a F2 method in the S2 class, so the S2 () method in the F2 class is executed. Subclass methods have high precedence when subclasses and parent classes have the same method. #just go to self. F2 () in such a time, go straight back to the original point to look for. For example, the example should go back to the S2 class for the F2 () method,#the method is found in subclass S2 and is executed directly. If not in the S2 class, look for the F2 () method in the parent class

Second, multiple inheritance

1. Simple Multiple inheritance

classC0:defF1 (self):Print('c0_f1')classC1 (C0):defF2 (self):Print('C1_f2')classC2:defF2 (self):Print('C2_f2')classC3 (C2,C1):#inherit from left to right, high priority on left    defF3 (self):Passobj=C3 () obj.f2 ( )#Output C2_F2

Out

C2_f2

2. Complex multiple inheritance

classC0:defF2 (self):Print('c0_f1')classC1 (C0):defF1 (self):Print('C1_f2')classC2:defF2 (self):Print('C2_f2')classC3 (C1,C2):#inherit from left to right, high priority on left    defF3 (self):Passobj=C3 () obj.f2 ( )#Output C0_F1

Out

C0_f1

Execution process:

3. Complex inheritance Relationship

classc_2:defF2 (self):Print('C_2_f2')classc_1 (c_2):defF2 (self):Print('C_1_f2')classC0 (c_2):defF1 (self):Print('C0_f2')classC1 (C0):defF1 (self):Print('C1_f2')classC2 (c_1):defF2 (self):Print('C2_f2')classC3 (C1,C2):#inherit from left to right, high priority on left    defF3 (self):Passobj=C3 () obj.f2 ( )#Output C0_F1

Out

C2_f2

Execution process

Summarize:

If the subclass's two parent class does not have a common parent class, it is a way to go to the black

If the subclass's two parent class has a common parent class, it is c1-->c0 and then c2-->c_1-->c_2

Inheritance of the python-class