On Mar 31, 2016, at 14:17 , William Stein wrote: > On Thu, Mar 31, 2016 at 2:08 PM, Justin C. Walker <jus...@mac.com> wrote: >> Hi, all, >> >> I have couple of questions regarding "attributes" in Python/Sage: >> >> 1. If hasattr(X, "foo") returns True, does that mean that "X.foo" should not >> blow up? > > What's the definition of "blow up"? I think X.foo could -- due to > Python "properties" -- run arbitrary Python code, e.g., to launch a > missile (or raise an exception).
Ooh...I have to try that... In my particular case, I'm not expecting percussion. I'm seeing exceptions (see following email). >> >> 2. Is there a way to tell, when hasattr(X, "foo") returns True, whether >> "X.foo" can be called? >> >> 3. If "X.foo" is callable, is it expected that "X.foo()" will *not* blow up >> with "Not Implemented"? > > Not necessarily. > > try: > X.foo() > except (NotImplementedError, AttributeError): > .... That's always the fall-back, I know. I suppose with object orientation, one has to expect this kind of thing... Thanks! -- Justin C. Walker, Curmudgeon at Large Institute for the Absorption of Federal Funds ----------- I'm beginning to like the cut of his jibberish. ----------- -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
