Why are the, dir () method and the _ _ dir__ () method different for a class?

check the documentation for the dir method, which has the following description:

If the object supplies a method named _ dir__, it will be used; otherwise
the default dir () logic is used and returns

that is, as long as the object itself has a _ _ dir__ method, the two should actually be the same. But try the following example and find that the two are not consistent: 

class A(object):
    pass
    
print(dir(A))
print(A.__dir__(A))
The

_ _ dir__ method has some extra properties, such as _ _ mro__ , _ _ name__ , and so on. Why?

Python
Jun.23,2021

your two print are not the same. The first one calls the _ _ dir__ method of A's metaclass, and the second one calls A's _ _ dir__ method.

I also took a look at the official document and your code. Your A does not customize the method of _ _ dir__. Of course, the two returns are different. Try this code of mine

. 
class A(object):
    def __dir__(self):
        return ['a', 'b', 'c']


a = A()
print(dir(a))
print(A.__dir__(a))

Previous: What is the location context of pseudo-elements in CSS?

Next: How to get the picture up when deploying the project to Sina Cloud?

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3e872-2bc73.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3e872-2bc73.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?