Import trouble

[Steve Holden]

Frans Englich wrote:

> Hello all,
> 
> I have a couple of questions related to module importing.
> 
> 1) When I start my Python program with `python foo.py` instead of simply 
> adding a interpreter comment on the first line and do `./foo.py`, some 
> "local" imports fails, I guess because current working directory is 
> different. Is CWD the only difference between running `python foo.py` and 
> `./foo.py`? What is the recommended way? (I guess security is one aspect that 
> can be argued)

You should post the exact error message together with a snippet of the 
code around the error. One possibility is that the "shebang" line 
(#!...) in your script is invoking a different Python than when you 
enter "python" and the shell locates it on your path.
> 
> 2) I use Python modules which are not usually installed(libxml2/libxslt) and 
> want to fail gracefully in case the modules aren't available; print an 
> informative message. Since these imports are done in several related 
> programs, I don't want to duplicate the code, but instead centralize it. The 
> problem is that when I put the module imports/exception code in a function, 
> it is as if it wasn't imported, even though there was no exceptions. I 
> suspect this is because the import is only done into the current namespace: 
> the function scope(instead of file scope as I want). Is there any solution to 
> my problem? Or should I solve it in another way?
> 
Craig Ringer has already answered this question.

> 3) And the last -- but funniest -- import problem: sometimes imports of 
> modules in "xml." fails, sometimes it works. For example, this code:
> from xml.dom.minidom import getDOMImplementation
> impl = getDOMImpmentation() #NameError: name 'getDOMImpmentation' is not 
> defined
> 
> fails as shown, and other times it works. When running pydoc as local web 
> server, it also sometimes fails, although I haven't been able to reproduce 
> for a error message. I have recent versions of PyXML and 4suite installed. 
> 
> What is wrong? Any idea what that could be wrong with my setup, which could 
> cause this?
> 
Again you should post a little more detail. In your example it looks 
like you made a simple spelling error: getDOMImpmentation instead of 
getDOMImplementation.

regards
  Steve
-- 
Steve Holden               http://www.holdenweb.com/
Python Web Programming  http://pydish.holdenweb.com/
Holden Web LLC      +1 703 861 4237  +1 800 494 3119