This should prove most enlightening: import Tkinter dir(Tkinter.Canvas)
On 10 Nov 2005 14:53:04 -0800, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > Suppose you want to write a subclass of some existing class you are > importing from a module you didn't write and that you don't want to > study the internals of, and you want to define a data member i in your > constructor. > > As in the following: > > from module1 import A > > class B(A): > def __init__(self): > A.__init__(self) > self.i= 0 > b= B() > > Now, 'i' might have already been defined by A or by the call to > A.__init__() so if you define it without knowing that, you could be > changing the behavior of A's methods in unknown ways, which is > obviously a bad thing. > > One way to avoid this is to run the following program to clear the name > 'i' first: > > from module1 import A > a= A() > print a.i > > If you get an AttributeError, you know the name 'i' is safe to use. If > you actually get some sort of report from the print statement, then you > will know that 'i' is not safe to use. > > This strikes me as a rather odd procedure to go through, but I don't > see any way around it. > > It there some other way to handle this issue? > > Do I actually need to study the sources for / implementation of > Tkinter.Canvas before I can safely subclass it (and assign attributes > to an instance of the subclass) or clear attribute names as I outlined > above? > > Chris Marshall > > -- > http://mail.python.org/mailman/listinfo/python-list > -- Steve Juranich Tucson, AZ USA -- http://mail.python.org/mailman/listinfo/python-list
