I'm trying to build a decorator-based dispatcher, such as you find used by Flask or Pyramid. I got something that works, but ran into a bit of a catch-22. The following code works, but only because foo() gets executed and sets the .mq_path-attribute. When starting the application and building a list of the dispatchable functions no attributes are thus set yet. I want to execute foo() driven by events.
I could "manually" prepare a list of functions ahead and updated as I add functions, but I enjoy the way Flask works, by just adding a decorator to a function that handles an URL (or in this case a MQ path).
list_of_paths = []
path_dispatcher = {}
def handle_mq(path):
def decorator(fn):
def decorated(*args,**kwargs):
decorated.mq_path = path
print "Hello from the handle_mq() decorator, your path is: {0}".format(path)
return fn(*args,**kwargs)
return decorated
return decorator
@handle_mq('/some/path')
def foo():
print "foo!"
foo() # <- this code only works if I first call the decorated function
for k, v in globals().items():
if hasattr(v, 'mq_path'):
list_of_paths.append(v.mq_path)
path_dispatcher[v.mq_path] = v
print list_of_paths
print path_dispatcher
path_dispatcher['/some/path']()
So basically the question is, how to gather a list of the decorated functions before they are first executed?
I'm on Python 2.7.
I found the answer!
list_of_paths = []
path_dispatcher = {}
def handle_mq(path):
def decorator(fn):
list_of_paths.append(path)
path_dispatcher[path] = fn
def decorated(*args,**kwargs):
print "Hello from handl_mq decorator, your path is: {0}".format(path)
return fn(*args,**kwargs)
return decorated
return decorator
@handle_mq('/some/path')
def foo():
print "foo!"
print list_of_paths
print path_dispatcher
path_dispatcher['/some/path']()