On 11/29/06, Tom Plunket <[EMAIL PROTECTED]> wrote: > Erik Max Francis wrote: > > > In dynamically-typed languages in general, explicit typechecks are not > > a good idea, since they often preclude user-defined objects from being > > used. Instead, try performing the call and catch the resulting > > TypeError: > > Good point, although I need to figure out if the thing can be called > without calling it, so I can build an appropriate UI. Basically I > expect three types of things in the 'value' field of the top-level > dictionary. The three sorts of things that I will deal with in the UI > are callable things (e.g. functions, for which Chris Mellon reminds me > about callable()), mappings (e.g. dictionaries, used similarly to the > top-level one), and sequences of strings. > > So I think callable() works for me in the general case, but now > trawling the documentation in that area I'm not sure how I can tell if > something is a mapping or if it's a sequence. > > The gist of the UI generation may be envisioned as: > > key is the name that gets assigned to the control. > value indicates that the UI element is a: > "group box" if the value is a mapping > series of "radio buttons" if the value is a sequence of strings > "check box" if the value is a function > > ...I've still gotta figure out the exact API, this is for a plugin > sort of system that'll be used by the manually-driven version of the > build process and this data is explicitly to build the UI for the > various tools that are available. >
Since a sequence can be viewed as a special case of a mapping (a dict with integer keys) I don't think there's a good general case way to tell. You could try indexing it with a string, a sequence will throw a TypeError, while a mapping will give you a result or a KeyError. You could also just rely on isinstance() checks. > thanks, > -tom! > -- > http://mail.python.org/mailman/listinfo/python-list > -- http://mail.python.org/mailman/listinfo/python-list
