On Feb 28, 4:00 pm, "Alf P. Steinbach" <al...@start.no> wrote: > * vsoler: > > > > > I have a class that is a wrapper: > > > class wrapper: > > def __init__(self, object): > > self.wrapped = object > > def __getattr__(self, attrname): > > print 'Trace: ', attrname > > #print arguments to attrname, how? > > return getattr(self.wrapped, attrname) > > > I can run it this way: > > >>>> x = wrapper([1,2,3]) > >>>> x.append(4) > > Trace: append > >>>> x.wrapped > > [1, 2, 3, 4] > > > I am able to capture the attribute name to x (that is, append). > > However, I do not know how to capture and print all of its arguments > > (in this case number 4). > > > How should I proceed? > > If your goal is just learning then in your __getattr__ you might return a > wrapper for the attribute instead of the attribute itself. Equip the wrapper > with a __call__ method if it is a method. And equip it with other special > methods as appropriate. > > I can imagine that that approach will lead to some practical problems, but it > may be great for learning. > > If your goal is tracing, then I suggest looking at the "trace" module. > > If your goal is something else purely practical, like intercepting method > calls > to do arbitrary things (logging, marshaling, whatever) then I suspect that it > might getspretty complicated, hairy. For specific method calls you might just > use subclassing, but for doing this in general, parameterized, you'd need to > about the same kinds of things as the trace module does. So I guess then one > idea might be to look at the source code of that module. > > But if that's what you intend to do, then best check first if there is an > existing solution. ParcPlace did this thing for a number of languages and > introduced a special term for it, I can't recall but something like > "cross-whatever mumbo jumbo concerns" plus one single catchy name. There might > be an existing Python implementation. > > Cheers & hth., > > - Alf
Alf, My goal is just learning. In the code provided in the post I just can't think of a method to "see", "capture" or "use" the parameters. I am going to study the __call__ method and see if I can figure out how I can capture the parameters. Thank you Alf -- http://mail.python.org/mailman/listinfo/python-list
