Formation

A generic functional middleware infrastructure for Python.

Take a look:

from datetime.datetime import now
from formation import wrap
from requests import get

def log(ctx, call):
    print("started")
    ctx = call(ctx)
    print("ended")
    return ctx

def timeit(ctx, call):
    started = now()
    ctx = call(ctx)
    ended = now() - started
    ctx['duration'] = ended
    return ctx

def to_requests(ctx):
    get(ctx['url'])
    return ctx

fancy_get = wrap(to_requests, middleware=[log, timeit])
fancy_get({'url':'https://google.com'})

Quick Start

Install using pip/pipenv/etc. (we recommend poetry for sane dependency management):

$ poetry add formation

Best Practices

A context object is a loose bag of objects. With that freedom comes responsibility and opinion.

For example, this is how Formation models a requests integration, with data flowing inside context:

• It models a FormationHttpRequest which abstracts the essentials of making an HTTP request (later shipped to requests itself in the way that it likes)
• It tucks FormationHttpRequest under the fmtn.req key.
• Additional information regarding such a request is kept alongside fmtn.req. For example a request id is kept in the req.id key. This creates a flat (good thing) dict to probe. The reason additional data does not have the fmtn prefix is that you can always build your own that uses a different prefix (which you cant say about internal Formation inner workings).

Thanks:

To all Contributors - you make this happen, thanks!

Copyright

Copyright (c) 2018 @jondot. See LICENSE for further details.