Add namespaces to task decorators

[fny]

The current mechanism to create namespaces is a lot of work. I've hacked together an example tasks decorator dynamically creates namespaces as needed.

@task('ns1.ns2.ns3') # or @task(collection='ns1.ns2.ns3') or @task(namespace=...)
def do_something(c):
    pass

I'm also of the opinion that anything marked with @task in tasks.py should be added to the root collection by default.

Here's a working example. I'd be more that happy to contribute this as a feature.

import invoke
from collections import deque
namespace = invoke.Collection()

def resolve_collection(namespace_str):
    """
    Returns an existing subcollection for a path (e.g. 'a.b.c') or creates them
    and returns the "leaf" subcollection.
    """
    collection_names = deque(namespace_str.split('.'))
    curr = namespace
    while True:
        collection_name = collection_names.popleft()
        try:
            subcollection = curr.subcollection_from_path(collection_name)
        except KeyError:
            subcollection = None
        # if theres not a matching subcollection add it
        if not subcollection:
            subcollection = invoke.Collection(collection_name)
            curr.add_collection(subcollection)
        curr = subcollection 

        if not collection_names:
            return subcollection

def task(collection = namespace, **kwargs):
    """invoke.task wrapped with some extra goodies"""
    def wrapper(task_fn):
        if isinstance(collection, invoke.Collection):
            collection.add_task(invoke.task(task_fn, **kwargs))

        if isinstance(collection, str):
            resolve_collection(collection).add_task(invoke.task(task_fn, **kwargs))
    return wrapper

#
# Usage
#

@task()
def this_task_will_be_in_the_default_namespace(c):
    pass

@task(collection='docs')
def this_task_will_be_in_docs(c):
    pass

[jzohrab]

Nice add. I don't feel that the current collection implementation is a lot of work, but it is error-prone, especially when managing a bunch of tasks. It would be nice to have something like this, where fqdn = "fully qualified domain name" (maybe too cryptic):

@task(fqdn='docs.build')    # nice-to-have equivalent to @task(collection='docs', name='build')
def do_build(c):
    "Do build"
    pass

and then a listing like:

inv --list

docs:
    docs.build    Do build