"questions?" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] >I am a little confused by an example in python book: > > class wrapper: > def __init__(self,object): > self.wrapped=object > def __getattr__(self,attrname): > print "Trace:",attrname (<<<===) > print getattr(self.wrapped,attrname) (*) > return getattr(self.wrapped,attrname) (**) > > x=wrapper({"a":1, "b":2}) > print x.keys() (**) > > > (*) will output: <built-in method keys of dict object at 0xb7f0f4f4> > while two (**) statements together will print the keys of the > dictionary which is ['a','b'] > > why (*) doen't output the same result as (**)? > > Thanks
Because the line (*) prints out the reference to a method, and the second line labeled (**) calls that method and prints that method's return value. As a hint, what does the line marked by (<<<===) print? I'm guessing it printed the attribute name 'keys'. __getattr__ didn't return the dict's keys, it returned the dict's "keys" method, which the calling code then invoked with ()'s, which invoked the wrapped object's "keys" method, which returned the wrapped object's keys, 'a' and 'b'. -- Paul -- http://mail.python.org/mailman/listinfo/python-list
