Re: Imports awareness in Imported modules problem

[Gabriel Genellina]

En Sun, 24 Aug 2008 07:34:41 -0300, Mohamed Yousef <ha******@gmail.comescribió:

On Sun, Aug 24, 2008 at 9:59 AM, Fredrik Lundh <fr*****@pythonware.comwrote:

>Mohamed Yousef wrote:

>>why am i doing this in the first place
I'm in the process of a medium project where imports of modules start
to make a jungle and i wanted all needed imports to be in a single
file (namely __init__.py)
and then all imports are made once and other modules feel it

Python doesn't use a global namespace -- importing a given module into one
module doesn't make it visible everywhere else (and trust me, this is a very
good thing).

why isn't it a good thing (even if optional)
consider the sitution in which a utility module is used every where
else - other modules -
you may say import it in them all ,

Yes. That way, when you see a name "foo" used in a module, you can look at the imports to see where it comes from. (BTW, this is why using "from module import *" is not a good idea)
Having a single global namespace is a lot worse.

what i changed it's name ? go back
change all imports... this doesn't seem good

Yes. How often do you change the module's name? You may use an alias if you want to be backwards compatible.

and what about package wide varailbles ?

If pkgA is a package, and you define a variable foo in its __init__.py, it is available as pkgA.foo - does it count as a "package wide variable"?

>>my goal is basically making W() aware of the re module when called
from A

to do that, add "import re" to the top of the C module.

and sys ,string.. etc add them all twice or four / n times ?

Every module has its own namespace, it contains its own set of imports, unrelated to others.
If you want to use the re, or sys, or string modules - import them. As F.L. has already pointed, a module is loaded from disk only the first time it is imported; subsequent imports find the module in sys.modules and do nothing.

remove one and then forget to remove one of them in a file and start
debugging ... this really doesn't look to be a good practice

Why is that? Importing an otherwise unused module is usually just a performance problem - at least for well-behaving modules that don't have side effects on import.

--
Gabriel Genellina