A couple of OOPython questions

David C. Fox davidcfox at post.harvard.edu
Tue Sep 9 19:55:38 CEST 2003


Alexy Khrabrov wrote:

> OK, now I go to my python prompt and I want to inspect my objects as
> returned by the CORBA server.  One of them represents an atom site.  I
> merrily type just its name to see the great unknown unwrap before my
> eyes.  Here:
> 
> 
>>>>a
> 
> <MMS.StructConf instance at 0x8cb1b44>
> 
> Hmm.  That's not what I hoped for.  Some fragments of code I saw run
> through my mind and I type in,
> 
> 
>>>>dir(a)
> 
> ['_NP_RepositoryId', '__doc__', '__init__', '__module__', 'beg_auth',
> 'beg_label', 'conf_type', 'details', 'end_auth', 'end_label', 'id']
> 
> Good, we're getting somewhere.  I also googled out vars(a), which
> seems to be the same as a.__dict__ (are they?...  why is __dict__ not
> shown above then?  2.2...)
> 
> Printing out gazillion fields by hand for each class is silly, they
> only wrap strings and numbers and other objects of that nature.  I am
> ready to dive in a recursive descent.  No such luck -- whoever created
> CORBA bindings for python didn't make those objects dictionary-like! 
> I can't get members by name, although they _are_ in some __dict__,
> useless apparently, until I supply __getitem__!
> 
> Is there an easy way to write something _once_, general enough, to
> print out a hierarchy of nested objects which just don't have
> __getitem__, although every field is either a string or a number or
> another object?

I'm not sure exactly what you are looking for, but here's a first 
attempt.  Save the following to a Python file called recursive_repr, 
import recursive_repr, and try print recursive_repr.pr(x).

import types

def type_or_class(x):
     """returns the type of a variable x, or its class when the latter is
     more specific, so that the types of two variables can be compared
     """
     t = type(x)
     if t is types.InstanceType:
# for old-style classes, __class__ is more specific
         return x.__class__
# for built-in types and new-style classes
     return t

def name_of_class(x):
     t = type_or_class(x)
     return "%s.%s" % (t.__module__, t.__name__)

def pr(x):
     if hasattr(x, '__dict__'):
#        return "class %s: %s" % (name_of_class(x), pr(x.__dict__))
         return {'class %s' % name_of_class(x) : pr(x.__dict__)}
     elif type(x) is type({}):
         d = {}
         for key, value in x.items():
             d[key] = pr(value)
#        return repr(d)
         return d
     return x


> 
> Cheers, 
> Alexy Khrabrov





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