D C's List: Python3

• It depends on how you want to access the import when you refer to it.
• from urllib import request # access request directly. mine = request()
• import urllib.request # used as urllib.request mine = urllib.request()

• You can also alias things yourself when you import for simplicity or to avoid masking built ins:

    

  from os import open as open_ # lets you use os.open without destroying the  # built in open() which returns file handles.

• There's very little difference in functionality, but the first form is preferential, as you can do

    

  from urllib import request, parse, error

• where in the second form that would have to be

    

  import urllib.request, urllib.parse, urllib.error

• import X

    

   

  Imports the module X, and creates a reference to that module in the  current namespace. Then you need to define completed module path to  access a particular attribute or method from inside the module (e.g.:  X.name or X.attribute)

• from X import *

    

   

  Imports the module X, and creates references to all public objects  defined by that module in the current namespace (that is, everything  that doesn’t have a name starting with _) or whatever name  you mentioned.

     

  Or, in other words, after you've run this statement, you can simply  use a plain (unqualified) name to refer to things defined in module X.  But X itself is not defined, so X.name doesn't work. And if name  was already defined, it is replaced by the new version. And if name in X is   changed to point to some other object, your module won’t notice.

     

  This makes all names from the module available in the local namespace.

• One pitfall about using from

    

  When you are import same name from two different modules:
• THE LAST IMPORT WILL WIN

8 more annotations...

• root.findall('inv:invoiceHeader', namespaces=dict(inv='http://www.stormware.cz/schema/version_2/invoice.xsd'))

• import urllib.request
• webpage = urllib.request.urlopen(url)
• webpage.read().decode('utf-8')

1 more annotation...

• >>> def getKey(item):

  ...     return item[0]
• >>> sorted(l, key=getKey)