[Tutor] Confusion regarding the 'from' statement

[Joel Goldstick]

On Tue, Aug 14, 2012 at 2:43 PM, David Rock <david at graniteweb.com> wrote:
> * Mazhar Hussain <yam.matt at gmail.com> [2012-08-14 23:24]:
>> the module object with the del statement. However what happens if I
>> try to import a name using 'from' that references a name in the
>> imported module that itself is not imported. Consider the following
>> example,here there are two modules mod1.py and mod2.py,
>>
>> #mod1.py
>> from mod2 import test

It is probably better to use:
import mod2

and then use
    mod2.test('mod1.py')

instead of your line below
>> test('mod1.py')
>>
>> #mod2.py
>> def countLines(name):
>>     print len(open(name).readlines())
>>
>> def countChars(name):
>>     print len(open(name).read())
>>
>> def test(name):
>>     print 'loading...'
>>     countLines(name)
>>     countChars(name)
>>     print '-'*10
>

The reason that import is better than from xxx import has to do with
name collisions.  If you have various modules and they all have a test
function, you won't be able to use them all.  The last one will be the
only one named test()

> Loosely speaking, it does import the other methods.  In order to
> successfully import test(), it has to resolve countLines() and
> countChars().  They won't be directly accessible, as they don't exist
> in the namespace, but test() knows about them.  You are reading too much
> into the comment that the module is "deleted".
>
> --
> David Rock
> david at graniteweb.com
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-- 
Joel Goldstick