On Mon, 25 Feb 2008 04:20:37 -0800 (PST), John Machin <[EMAIL PROTECTED]> wrote: > On Feb 25, 10:42 pm, Doug Morse <[EMAIL PROTECTED]> wrote: > > Hi, > > > > My apologies for troubling for what is probably an easy question... it's > > just > > that can't seem to find an answer to this anywhere (Googling, pydocs, > > etc.)... > > > > I have a class method, MyClass.foo(), that takes keyword arguments. For > > example, I can say: > > > > x = MyClass() > > x.foo(trials=32) > > > > Works just fine. > > > > What I need to be able to do is call foo() with a string value specifying > > the > > keyword (or both the keyword and value would be fine), something along the > > lines of: > > > > x = MyClass() > > y = 'trials=32' > > x.foo(y) # doesn't work > > > > or > > > > x.MyClass() > > y = 'trials' > > x.foo(y = 32) # does the "wrong" thing > > > > Surely there's some way to use a string's value as the key for making a > > method > > call with a keyword argument? > > > > Just for completeness, my goal is simply to read a bunch of key/value pairs > > from an INI file (using ConfigObj) and then use those key/value pairs to > > set a > > (3rd party) object's parameters, which must be done with a call along the > > lines of "instance.set(key=value)". Obviously, I could create a huge > > if..elif > > statement along the lines of "if y = 'trials': x.foo(trials=32); elif y = > > 'speed': x.foo(speed=12);" etc., but then the statement has to be maintained > > every time a new parameter is added/changed etc. Plus, such a solution > > seems > > to me grossly inelegant and un-Pythonic. > > > > I'm not quite sure what foo() is really supposed to do ... however the > built-in function setattr is your friend. Assuming that ini_dict > contains what you have scraped out of your .ini file, you can do: > x = MyCLass() > for key, value in ini_dict.items(): > setattr(x, key, value) > You may prefer (I would) to do it inside the class, and maybe do some > checking/validation: > class MyClass(object): > def load(self, adict): > for k, v in adict.items(): > # do checking here > setattr(self, k, v) > # much later > x = MyClass() > x.load(ini_dict) > > HTH, > John
Hi John, Your response is most helpful and informative -- thanks! I don't think that setattr() is exactly what I need, though, as foo() doesn't actually create or update its instance attributes. What I need to be able to do is call foo() specifying keyword arguments not directly but viz a viz another variable or variables that contain the keywords and values. I'm pretty sure I just found the solution, which is to use the **-operator on a dictionary. Actually, ConfigObj (the INI file reader) subclasses from __builtin__.dict (i.e., the class/object *is* a dictionary), so the following seems to work perfectly: x.foo(**config) This sends ALL the key/value pairs in config as keyword/value pairs to foo(), which is exactly what I need. Just FYI, I located this solution via Google shortly after posting, so I have sent a cancel request on my original post. Thanks again! Doug -- http://mail.python.org/mailman/listinfo/python-list
