Changes in import statement python3

Question

I don t understand the following from pep-0404     In Python 3  implicit relative imports within packages are no longer   available - only absolute imports and explicit relative imports are   supported  In addition  star imports  e g  from x import    are only   permitted in module level code    What is a relative import  In what other places star import was allowed in python2  Please explain with examples

User · Answer

For relative imports see the documentation. A relative import is when you import from a module relative to that module's location, instead of absolutely from sys.path.

As for import *, Python 2 allowed star imports within functions, for instance:

>>> def f():
...     from math import *
...     print sqrt

A warning is issued for this in Python 2 (at least recent versions). In Python 3 it is no longer allowed and you can only do star imports at the top level of a module (not inside functions or classes).

User · Answer

To support both Python 2 and Python 3  use explicit relative imports as below  They are relative to the current module  They have been supported starting from 2 5   from  sister import foo from   import brother from   aunt import bar from    import uncle

User · Answer

Relative import happens whenever you are importing a package relative to the current script package   Consider the following tree for example   mypkg  -- base py  -- derived py   Now  your derived py requires something from base py  In Python 2  you could do it like this  in derived py    from base import BaseThing   Python 3 no longer supports that since it s not explicit whether you want the  relative  or  absolute  base  In other words  if there was a Python package named base installed in the system  you d get the wrong one   Instead it requires you to use explicit imports which explicitly specify location of a module on a path-alike basis  Your derived py would look like   from  base import BaseThing   The leading   says  import base from module directory   in other words   base maps to   base py   Similarly  there is    prefix which goes up the directory hierarchy like      with   mod mapping to    mod py   and then     which goes two levels up        mod py  and so on   Please however note that the relative paths listed above were relative to directory where current module  derived py  resides in  not the current working directory      BrenBarn has already explained the star import case  For completeness  I will have to say the same      For example  you need to use a few math functions but you use them only in a single function  In Python 2 you were permitted to be semi-lazy   def sin degrees x       from math import       return sin degrees x     Note that it already triggers a warning in Python 2   a py 1  SyntaxWarning  import   only allowed at module level   def sin degrees x     In modern Python 2 code you should and in Python 3 you have to do either   def sin degrees x       from math import sin  degrees     return sin degrees x     or   from math import    def sin degrees x       return sin degrees x

User · Answer

Added another case to Michal G  rny s answer   Note that relative imports are based on the name of the current module  Since the name of the main module is always    main     modules intended for use as the main module of a Python application must always use absolute imports

[python] Changes in import statement python3

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