[Tutor] Importing and creation on the fly

[Dave Kuhlman]

On Tue, Jun 26, 2007 at 12:20:18PM -0400, Tino Dai wrote:
> Hi there,
> 
>     I've been banging my head on this for about two weeks, and I can't
> figure out a solution to this. I'm wondering if you could assist me on this
> pesky problem.
> 
>     I'm reading in an xml file that has the name of class, location, and
> the filename into a dictionary. I want to import these classes and create
> instances of them.  The code in question is as follows:
> 
> 36       for xmlKey in self.dictXML.keys():
> 37             if not self.dictXML[xmlKey]['location'] in sys.path and \
> 38             not self.dictXML[xmlKey]['location'] == os.getcwd():
> 39                 sys.path.append(self.dictXML[xmlKey]['location'])
> 40             try:
> 41                 if os.stat(self.dictXML[xmlKey]['location'] + \
> 42                 self.dictXML[xmlKey]['filename']):
> 43                     eval('import ' + self.dictXML[xmlKey]["class"])
> <-- syntax error here
> 44                     actionStmt=self.dictXML[xmlKey]["class"] + '.' +
> self.dictXML[xmlKey]["class"] + '()' 45
> 45                          self.objList.append(eval(actionStmt))
> 46             except:
> 47                 pass
> 
> 
> I have also tried: __import__(self.dictXML[xmlKey]["class"]), which gave me
> an error when I did the eval(actionStmt). Could anybody shed some light on
> this? Thanks in advance.

For the task of importing, look at the "imp" module:

    http://docs.python.org/lib/module-imp.html

Also, the "inspect" module may be of help:

    http://docs.python.org/lib/module-inspect.html

In particular, look at the the inspect.getmembers() and
inspect.isclass() methods.

Dave


-- 
Dave Kuhlman
http://www.rexx.com/~dkuhlman