Python decorators.
I finally found a non-trivial reason to implement a Python decorator. I make extensive use of Python keyword arguments in the pysmug API and map those spellings to SmugMug keyword arguments. The algorithm for converting a Python spelling to a SmugMug spelling is pretty straight forward and easily wrapped up in a function. Originally, the first line of every function required formatting the keywords into SmugMug-style spellings by calling self._prepare_keywords(**kwargs). It occurred to me this is a perfect use case for decorators so I converted the code from a class method to a function, moved the call up a line, prefixed a @ and voilà, a far more explicit communication about how this method handles keyword arguments — love it.
In version 0.4 of pysmug I refactored my code from this:
def _login(self, handler, **kwargs): kwargs = self._prepare_keywords(**kwargs) method = kwargs.get("method", None) ...
to this:
@smugmug_keywords def _login(self, handler, **kwargs): method = kwargs.get("method", None) ...
by using this function (the function mg was originally the _prepare_keywords function):
def smugmug_keywords(fn): """Prepare the keywords for sending to SmugMug. The following operations are performed:: 1. If the key is "method", continue. 2. If the key starts with an upper case letter, continue. 3. If the key is in {methods.apikeys}, replace the key. 4. If the key ends with {id}, upper case the first letter and {ID} and replace the key. 5. Else, upper case the first letter only and replace the key. @param fn: the decorated function """ def mg(*args, **kwargs): items = kwargs.items() for k, v, in items: if k == "method": continue if k[0].isupper(): continue lk = k.lower() if lk in apikeys: key, func = apikeys[lk] del kwargs[k] kwargs[key] = func(v) if func else v else: del kwargs[k] if lk.endswith("id"): kwargs[lk[:-2].title() + "ID"] = v else: kwargs[lk.title()] = v return fn(*args, **kwargs) return mg
This function is an argument for Erlang-style pattern matching.
Hi,
I find grey on black to be hard to read. It detracts from the message.
- Paddy.
@Paddy - I listened.
thanks, brian