Python data types determine the difference between type and isinstance

In the project, we will validate the parameter type passed by the client on each interface, and return to the client "parameter error" error code if the validation does not pass.

This not only facilitates debugging, but also increases robustness. Because the client can cheat, do not easily believe that the client passed over the parameters.

Validation types are useful with the type function, such as

>>type (' foo ') = = str

True

>>type (2.3) in (int,float)

True

Now that you have type () to judge the types, why are there isinstance ()?

One obvious difference is in judging subclasses.

Type () does not consider a subclass to be a parent class type.

Isinstance () considers a subclass to be a parent class type.

Thousand words is inferior to one yard.

Class Foo (object):    Pass    class Bar (foo):    pass    print type (foo ()) = = Fooprint Type (Bar ()) = = Fooprint Isinstance (Bar (), foo)   class Foo (object):    Pass   class Bar (foo):    pass   print type (foo ()) = = Fooprint type (bar ()) = = Fooprint Isinstance (bar (), Foo) output truefalsetrue

It is important to note that the old class is not the same as the type () result of the new class. The old class is all .

Class A:    pass    class B:    Pass    class C (object):    pass    print ' Old Style class ', type (A ()) print ' Old Style class ', type (b ()) print ' New Style class ', type (C ()) Print type (A ()) = = Type (b ())   class A:    pass   class b:< C9/>pass   class C (object):    pass   print ' Old Style class ', type (A ()) print ' Old Style class ', type (B ()) Print ' New Style class ', type (C ()) Print type (A ()) = = Type (B ()) output old style class old 
 
  
   
  style class 
  
   
    
   New Style class
  
    
     
    True
   
     
   
 
  

There is no saying isinstance is better than type. Only one is better suited to demand.

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