[Tutor] Dynamically composing a module name

[Max Noel]

On Apr 19, 2005, at 21:22, Tim Johnson wrote:

> Hello Pythonmeisters:
>
> Is it possible to dynamically compose a module name
> for import?
>
> Pointers to documentation or other discussions would
> be sufficient at this time.
>
> thanks

	Ah, metaprogramming. I must admit I can't think of a way. Or rather, I  
did think of a few but they don't work:
- module isn't a built-in (yet importing a module and calling type on  
it returns <type 'module'>).
- eval("import os") raises a SyntaxError.



	However, the __import__ built-in function seems promising, although I  
have trouble seeing how it is used. Witness:

 >>> __import__("os")
<module 'os' from  
'/System/Library/Frameworks/Python.framework/Versions/2.3/lib/ 
python2.3/os.pyc'>
 >>> dir()
['__builtins__', '__doc__', '__name__']
 >>>

 >>> __import__("sys").version_info
(2, 3, 0, 'final', 0)


	So calling the function returns the module as an object, but it is not  
imported in the usual sense of the word. But you can use functions from  
it...

	Oh, wait, I get it. It's so obvious I wonder why I didn't see it  
before.

 >>> sys = __import__("sys")
 >>> sys.version_info
(2, 3, 0, 'final', 0)


	There you are. So yes, it can be done, and quite easily at that  
(although not as easily as in Ruby, IIRC, whose metaprogramming  
features truly frightened me last time I had a look at it).

-- Max
maxnoel_fr at yahoo dot fr -- ICQ #85274019
"Look at you hacker... A pathetic creature of meat and bone, panting  
and sweating as you run through my corridors... How can you challenge a  
perfect, immortal machine?"