On Fri, Apr 08, 2005 at 01:33 +0200, Valentino Volonghi aka Dialtone wrote:
> holger krekel wrote:
>
> >I would be surprised if my brand-new hack breaks yours (because that
> >is exactly what it is trying to avoid) but i've learned that "import"
> >makes the impossible possible and vice versa.
> >
> >cheers,
> >
> >
> It was a quick fix in my case :).
Everybody says that, see "piles of hacks" earlier :-)
> It shouldn't be hard to figure out a common failing pattern in import
> magic. for example:
> nevow was failing because of namedAny that imports a module from a
> string representing the entire path in PYTHONPATH.
brain shaking already ...
> from nevow import util
> In [6]:util.namedAny('nevow.flat.ten')
> Out[6]:<module 'nevow.flat.ten' from
> '/Volumes/dati/Sviluppo/Nevow/nevow/flat/ten.pyc'>
>
> namedAny is this one:
>
> def namedAny(name):
> """Get a fully named package, module, module-global object, or
> attribute.
> """
> names = name.split('.')
> topLevelPackage = None
> moduleNames = names[:]
> while not topLevelPackage:
> try:
> trialname = '.'.join(moduleNames)
> topLevelPackage = __import__(trialname)
> except ImportError:
> # if the ImportError happened in the module being imported,
> # this is a failure that should be handed to our caller.
> # count stack frames to tell the difference.
>
> # string-matching is another technique, but I think it could be
> # fooled in some funny cases
> #if sys.exc_info()[1] != "cannot import name %s" % trialname:
> # raise
> import traceback
> if len(traceback.extract_tb(sys.exc_info()[2])) > 1:
> raise
> moduleNames.pop()
>
> obj = topLevelPackage
> for n in names[1:]:
> obj = getattr(obj, n)
>
> return obj
>
> But I can't remember exactly the failure. The ML is here to help
> (something about the PYTHONPATH anyway).
I have written similar code and there were always side cases
that made it at least hard to debug and find the actual problem
in the program.
cheers,
holger
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