forge (python signatures)
forge (python) signatures for fun and profit
forge is an elegant Python package for revising function signatures at runtime. This libraries aim is to help you write better, more literate code with less boilerplate.
forge is a Python-only package hosted on PyPI for Python 3.5+.
$ pip install python-forge
Consider a library like requests that provides a useful API for performing HTTP requests. Every HTTP method has it’s own function which is a thin wrapper around requests.Session.request. The code is a little more than 150 lines, with about 90% of that being boilerplate. Using forge we can get that back down to about 10% it’s current size, while increasing the literacy of the code.
import forge import requests request = forge.copy(requests.Session.request, exclude='self')(requests.request) def with_method(method): revised = forge.modify( 'method', default=method, bound=True, kind=forge.FParameter.POSITIONAL_ONLY, )(request) revised.__name__ = method.lower() return revised post = with_method('POST') get = with_method('GET') put = with_method('PUT') delete = with_method('DELETE') options = with_method('OPTIONS') head = with_method('HEAD') patch = with_method('PATCH')
So what happened? The first thing we did was create an alternate request function to replace requests.request that provides the exact same functionality but makes its parameters explicit:
# requests.get() looks like this: assert forge.repr_callable(requests.get) == 'get(url, params=None, **kwargs)' # our get() calls the same code, but looks like this: assert forge.repr_callable(get) == ( 'get(url, params=None, data=None, headers=None, cookies=None, ' 'files=None, auth=None, timeout=None, allow_redirects=True, ' 'proxies=None, hooks=None, stream=None, verify=None, cert=None, ' 'json=None' ')' )
Next, we built a factory function with_method that creates new functions which make HTTP requests with the proper HTTP verb. Because the method parameter is bound, it won’t show up it is removed from the resulting functions signature. Of course, the signature of these generated functions remains explicit, let’s try it out:
response = get('http://google.com') assert 'Feeling Lucky' in response.text
You can review the alternate code (the actual implementation) by visiting the code for requests.api.
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