Re: Imports awareness in Imported modules problem

[Mohamed Yousef]

On Sun, Aug 24, 2008 at 9:59 AM, Fredrik Lundh <fredrik@python ware.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 , what i changed it's name ? go back
change all imports... this doesn't seem good
and what about package wide varailbles ?

(it uses a global module cache, though, so it's only the first import that
actually loads the module)
>

>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 ?
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

see this page for a little more on Python's import mechanism:
>

http://effbot.org/zone/import-confusion.htm

>

Regards,
Mohamed Yousef

[alex23]

Re: Imports awareness in Imported modules problem

On Aug 24, 8:34 pm, "Mohamed Yousef" <harrr...@gmail .comwrote:

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

No, having each module contain all of the necessary imports for itself
-is- good practice.

While it might seem more convenient to define all of your imports in
one place, what you're really doing is injecting -all- references to -
all- imported items into -every- module. Having a global soup of
imported items like such is much, much harder to control for
unexpected name conflicts.

Ideally, you want each module's namespace to -only- contain references
to the external entities it's actually using. This not only makes each
module self-contained and more open to independent re-use, it makes
them -incredibly- easier to debug.

Please don't confuse temporary convenience with good practice.

[Mohamed Yousef]

Re: Imports awareness in Imported modules problem

On Sun, Aug 24, 2008 at 2:27 PM, alex23 <wuwei23@gmail. comwrote:

On Aug 24, 8:34 pm, "Mohamed Yousef" <harrr...@gmail .comwrote:

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

>
No, having each module contain all of the necessary imports for itself
-is- good practice.
>
While it might seem more convenient to define all of your imports in
one place, what you're really doing is injecting -all- references to -
all- imported items into -every- module. Having a global soup of
imported items like such is much, much harder to control for
unexpected name conflicts.
>
Ideally, you want each module's namespace to -only- contain references
to the external entities it's actually using. This not only makes each
module self-contained and more open to independent re-use, it makes
them -incredibly- easier to debug.
>
Please don't confuse temporary convenience with good practice.

mm , this seems to be logically or another good behind logic . as PHP
already uses that convention -from which i thought python also does -

but what about module-wide variables what is the approach to them ,
will i have to store them in a memory table (SQL) , or keep passing
them between objects - which i really hate -

[alex23]

Re: Imports awareness in Imported modules problem

On Aug 24, 9:43 pm, "Mohamed Yousef" <harrr...@gmail .comwrote:

but what about module-wide variables what is the approach to them ,
will i have to store them in a memory table (SQL) , or keep passing
them between objects - which i really hate -

If you have a set of global variables that you want to share among
modules, put them all into a module.

config.py:
var1 = 'a'

a.py:
import config
config.var1 = 'z'

b.py:
import config
print config.var1

>>import a
>>import b

z

A module is only really imported once; each subsequent import is given
a reference to that imported module, so any changes to the module
values are shared amongst each importing module.

[Fredrik Lundh]

Re: Imports awareness in Imported modules problem

Mohamed Yousef wrote:

mm , this seems to be logically or another good behind logic . as PHP
already uses that convention -from which i thought python also does -

I'm not sure arguing with anyone who tries to help you is the best way
to learn a new programming language.

</F>