jrpfinch wrote: > I am constructing a simple class to make sure I understand how classes > work in Python (see below this paragraph). > > It works as expected, except the __add__ redefinition. I get the > following in the Python interpreter: > >>>> a=myListSub() >>>> a > [] >>>> a+[5] > Traceback (most recent call last): > File "<stdin>", line 1, in ? > TypeError: 'str' object is not callable >>>> > > Please could you let me know where I am going wrong. I have hacked > around with the code and tried googling this error message but am > having difficulty finding the source of the problem.
> class myList: > def __init__ (self,value=[]): > self.wrapped=[] > for x in value : > self.wrapped.append(x) > def __repr__ (self): > return `self.wrapped` > def __getattr__ (self,attrib): > return getattr(self.wrapped,attrib,'attribute not found') When Python is looking for an attribute that neither exists in myList nor the 'wrapped' list, you give back a string. In your case this happens for the __coerce__() method, and the interpreter ends up calling "attribute not found" which of course must fail. The solution: - Don't provide a bogus default for getattr(), and get a traceback that is easier to understand. - Use new-style classes (i.e. class myList(object): ...) which look for special methods in the class, not the instance. Peter -- http://mail.python.org/mailman/listinfo/python-list
