I am using Python RPyC to communicate between two machines. Since the link may be prone to errors I would like to have a generic wrapper function which takes a remote function name plus that function's parameters as its input, does some status checking, calls the function with the parameters, does a little more status checking and then returns the result of the function call. The wrapper should have no knowledge of the function, its parameters/parameter types or the number of them, or the return value for that matter, the user has to get that right; it should just pass them transparently through.
I get the getattr(conn.root, function)()
pattern to call the function but my Python expertise runs out at populating the parameters. I have read various posts on the use of *arg
and **kwarg
, in particular this one, which suggests that it is either difficult or impossible to do what I want to do. Is that correct and, if so, might there be a scheme which would work if I, say, ensured that all the function parameters were keyword parameters?
I do own both ends of this interface (the caller and the called) so I could arrange to dictionary-ise all the function parameters but I'd rather not make my API too peculiar if I could possibly avoid it.
Edit: the thing being called, at the remote end of the link, is a class with very ordinary methods, e.g.;
def exposed_a(self)
def exposed_b(self, thing1)
def exposed_c(self, thing1=None)
def exposed_d(self, thing1=DEFAULT_VALUE1, thing2=None)
def exposed_e(self, thing1, thing2, thing3=DEFAULT_VALUE1, thing4=None)
def exposed_f(self, thing1=None, thing2=None)
...where the types of each argument (and the return values) could be string, dict, number or list.
And it is indeed, trivial, my Goggle fu had simply failed me in finding the answer. In the hope of helping anyone else who is inexperienced in Python and is having a Google bad day:
One simply takes
*arg
and**kwarg
as parameters and passes them directly on, with the asterisks attached. So in my case, to do my RPyC pass-through, whereconn
is the RPyC connection:Then, for example, a call to my
exposed_e()
method above might be:(the
exposed_
prefix being added automagically by RPyC in this case).And of course one could put a
try:
/except ConnectionRefusedError:
around thegetattr()
call inmy_passthru()
to generically catch the case where the connection has dropped underneath RPyC, which was my main purpose.