On Sun, Nov 24, 2013 at 2:45 PM, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > On Sun, 24 Nov 2013 05:04:16 -0800, Devin Jeanpierre wrote: > >> On Sun, Nov 24, 2013 at 4:52 AM, Marc Aymerich <glicer...@gmail.com> >> wrote: >>> Hi, >>> I'm playing with python internals to make objects behave like this: >>> >>> if I access to "object.attribute" I want to return the result of an >>> HTTP GET request. However if i call "object.attribute()" I want an HTTP >>> POST request to be executed. >> >> Uh oh. What you want is impossible. You cannot call an attribute without >> first accessing it. :( > > Not quite impossible. All you need is an object that behaves like a > string, except it has a __call__ method. Here's a sketch of a solution, > completely untested. > > > class CallableString(str): > # Like a string, but callable. > def function(self): > raise NotImplementedError( > "this must be overridden on the instance" > ) > def __call__(self): > return self.function() > > > class Magic_HTTP_Thing: > @property > def attribute(self): > result = CallableStr(self.do_get()) > result.function = lambda: self.do_put() > def do_get(self): > # Do a HTTP GET request. > return "Get stuff" > def do_put(self): > # Do a HTTP PUT request. > return "Put stuff"
OMG steven, it actually works :) >>> class CallableString(str): ... # Like a string, but callable. ... def function(self): ... raise NotImplementedError( ... "this must be overridden on the instance" ... ) ... def __call__(self): ... return self.function() ... >>> >>> class Magic_HTTP_Thing: ... @property ... def attribute(self): ... result = CallableString(self.do_get()) ... result.function = lambda: self.do_put() ... return result ... def do_get(self): ... # Do a HTTP GET request. ... return "Get stuff" ... def do_put(self): ... # Do a HTTP PUT request. ... return "Put stuff" ... >>> >>> Magic_HTTP_Thing().attribute 'Get stuff' >>> Magic_HTTP_Thing().attribute() 'Put stuff' > > Possible or not, it doesn't seem like a reasonable API to me. yeah, this is a "corner case" of our REST API, I have some badly design endpoints that mostly behave like functions, but some of them also contain state information that you can GET, I was trying to map this behavior to python objects and this interface is the best that occurred to me :) -- Marc -- https://mail.python.org/mailman/listinfo/python-list
