Should I use import os path or import os

Question

According to the official documentation  os path is a module  Thus  what is the preferred way of importing it     Should I always import it explicitly  import os path   Or       Is importing os enough  import os   Please DON T answer  importing os works for me   I know  it works for me too right now  as of Python 2 6   What I want to know is any official recommendation about this issue  So  if you answer this question  please post your references

User · Accepted Answer

os path works in a funny way  It looks like os should be a package with a submodule path  but in reality os is a normal module that does magic with sys modules to inject os path  Here s what happens    When Python starts up  it loads a bunch of modules into sys modules  They aren t bound to any names in your script  but you can access the already-created modules when you import them in some way    sys modules is a dict in which modules are cached  When you import a module  if it already has been imported somewhere  it gets the instance stored in sys modules   os is among the modules that are loaded when Python starts up  It assigns its path attribute to an os-specific path module  It injects sys modules  os path     path so that you re able to do  import os path  as though it was a submodule    I tend to think of os path as a module I want to use rather than a thing in the os module  so even though it s not really a submodule of a package called os  I import it sort of like it is one and I always do import os path  This is consistent with how os path is documented     Incidentally  this sort of structure leads to a lot of Python programmers  early confusion about modules and packages and code organization  I think  This is really for two reasons   If you think of os as a package and know that you can do import os and have access to the submodule os path  you may be surprised later when you can t do import twisted and automatically access twisted spread without importing it  It is confusing that os name is a normal thing  a string  and os path is a module  I always structure my packages with empty   init   py files so that at the same level I always have one type of thing  a module package or other stuff  Several big Python projects take this approach  which tends to make more structured code

User · Answer

Definitive answer  import os and use os path  do not import os path directly   From the documentation of the module itself    gt  gt  gt  import os  gt  gt  gt  help os path      Instead of importing this module directly  import os and refer to this module as os path   The  os path  name is an alias for this module on Posix systems  on other systems  e g  Mac  Windows   os path provides the same operations in a manner specific to that platform  and is an alias to another module  e g  macpath  ntpath

User · Answer

As per PEP-20 by Tim Peters   Explicit is better than implicit  and  Readability counts    If all you need from the os module is under os path  import os path would be more explicit and let others know what you really care about   Likewise  PEP-20 also says  Simple is better than complex   so if you also need stuff that resides under the more-general os umbrella  import os would be preferred

User · Answer

Interestingly enough  importing os path will import all of os   try the following in the interactive prompt   import os path dir os    The result will be the same as if you just imported os   This is because os path will refer to a different module based on which operating system you have  so python will import os to determine which module to load for path   reference  With some modules  saying import foo will not expose foo bar  so I guess it really depends the design of the specific module     In general  just importing the explicit modules you need should be marginally faster   On my machine   import os path  7 54285810068e-06 seconds  import os  9 21904878972e-06 seconds  These times are close enough to be fairly negligible  Your program may need to use other modules from os either now or at a later time  so usually it makes sense just to sacrifice the two microseconds and use import os to avoid this error at a later time   I usually side with just importing os as a whole  but can see why some would prefer import os path to technically be more efficient and convey to readers of the code that that is the only part of the os module that will need to be used   It essentially boils down to a style question in my mind

User · Answer

Couldn t find any definitive reference  but I see that the example code for os walk uses os path but only imports os

User · Answer

Common sense works here  os is a module  and os path is a module  too  So just import the module you want to use    If you want to use functionalities in the os module  then import os  If you want to use functionalities in the os path module  then import os path  If you want to use functionalities in both modules  then import both modules   import os import os path    For reference    Lib idlelib rpc py uses os and imports os  Lib idlelib idle py uses os path and imports os path  Lib ensurepip init py uses both and imports both

[python] Should I use `import os.path` or `import os`?

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