Style question: Importing modules from packages - 'from' vs 'as'

[Terry Reedy]

On 12/3/2014 6:02 AM, Chris Angelico wrote:
> When importing a module from a subpackage, it's sometimes convenient
> to refer to it throughout the code with a one-part name rather than
> two. I'm going to use 'os.path' for the examples, but my actual
> use-case is a custom package where the package name is, in the
> application, quite superfluous.
>
> Throughout the code, I want to refer to "path.split()",
> "path.isfile()", etc, without the "os." in front of them. I could do
> either of these:
>
> import os.path as path
> from os import path
>
> Which one would you recommend? Does it depend on context?

I confirmed that they do the same thing for submodules.
 >>> import os.path as pth
 >>> from os import path
 >>> pth
<module 'ntpath' from 'C:\\Programs\\Python34\\lib\\ntpath.py'>
 >>> path
<module 'ntpath' from 'C:\\Programs\\Python34\\lib\\ntpath.py'>
 >>> id(pth)
4319096
 >>> id(path)
4319096

I and most code I have seen uses "from tkinter import ttk".

> An "as" import works only if it's a module in a package, where the
> "from" import can also import other objects (you can't go "import
> pprint.pprint as pprint"). I'm fairly sure that's an argument... on
> one side or another.

"import tkinter.ttk as ttk" makes it clear that ttk is a module rather 
than, say, a class.  That might make things easier for the reader.  On 
the other hand, duplication implies that there might be a real renaming, 
so having to compare to see that there is not, is extra work.

from idlelib import EditorWindow
import idlelib.EditorWindow as EditorWindow

-- 
Terry Jan Reedy