Skip to main content
Join the official 2019 Python Developers SurveyStart the survey!

A command line argument parsing utility using python class-based namespace for better IDE static auto-completion

Project description

  • 2019/06/11: Now supports tab-completion at the command line!
  • 2018/11/08: Now supports both python 3.52 as well as 3.6! :bangbang::star:

What is “Experiment Parameter Hell”?

“Experiemnt Parameter Hell” occurs when you have more than twenty parameters for your ML project that are all defined as string/function parameters with click or argparse. Sometimes these parameters are defined in a launch script and passes through five layers of function calls during an experiment.

Your Python IDEs work very hard on static code-block analysis to intelligently make you more productive, and the “parameter hell” breaks all of that.

In your ML project, you want to avoid using dictionaries or opaque argparse definitions as much as you can. You want to write those parameters declaratively instead. This way, your IDE can actually help you navigate through those layers of function calls.

Writing documentation as uhm…, man page?

Params-Proto exposes your argument namespace’s doc string as the usage note. For users of your code-block, there is no better help than the one that comes with the script itself!

With params-proto, your help is only one -h away :)

And Your code-block becomes the documentation.

Why Use Params_Proto Instead of Click or Argparse?

Because this is declarative, which makes it easy to refactor your code-block and find variable references.

  • You want to place all of the arguments under a namespace that can be statically checked.
  • This allows your IDE to:
    1. Find usage of each argument
    2. jump from anywhere in your code-block base to the declaration of that argument
    3. refactor your argument name in the entire code-block base automatically

Params_proto is the declarative way to write command line arguments, and is the way to go for ML projects.

Tab-completion for your script!

params_proto uses argparse together with argcomplete, which enables command line autocomplete on tabs! To enable run

pip install params-proto
# then:

For details, see `argcomplete’s documentation <>`__.

Simple Example (with batteries included!!):battery:

from params_proto import cli_parse, BoolFlag, Proto

class Args:
        Generator for the 2D Particle Map Dataset. See Usage help below:
    load = Proto(None, dtype=str, help="to visualize existing data located at this path")
    x_dim = Proto(2, help="The dimension for the observation space")
    data_size = Proto(20, help="The size of the dataset. Note we x2 because we generate transitions.")
    show_plot = BoolFlag(True, help="Shows the plot when true.")

def train():
    D = Discriminator(Args.x_dim)

def launch(**kwargs):

if __name__ == "__main__":

now, if you run this code-block, it gives you this help in the command line:

(/Users/ge/anaconda/envs/some-project)  git:(master) python -m -h
usage: [-h] [--load LOAD] [--x-dim X_DIM] [--data-size DATA_SIZE]

[README] Generator for the 2D Particle Map Dataset. See Usage help below:

optional arguments:
  -h, --help            show this help message and exit
  --load LOAD           to visualize existing data located at this path
  --x-dim X_DIM         The dimension for the observation space
  --data-size DATA_SIZE
                        The size of the dataset. Note we x2 because we
                        generate transitions.
  --show-plot           Shows the plot when true.

Now, isn’t this awesome? :bang::stars:

How to override when calling from python

It is very easy to over-ride the parameters when you call your function: have most of your training code-block directly reference the parser namespace (your configuration namespace really), and just monkey patch the attribute.

params-proto works very well with the clound ML launch tool jaynes. Take a look at the automagic awesomeness of jaynes:)



  • [x] publish
  • [x] add test
  • [x] add python3.52 test on top of python3.6 test.


pip install params-proto


To use a python namespace to declare commandline argments

Updated We now use a Proto helper function to declare the argparse arguments! See example below:

Simple example showing how to use python namespace to declare command line arguments:

note: for boolean, use bool or "bool". params_proto will automatically use distutils.util.strtobool to parse it into bool. Details look here

from .params_proto import cli_parse, is_hidden, Proto, ParamsProto, proto_signature

def test_cli_proto():
    class G(ParamsProto):
        """Supervised MAML in tensorflow"""
        npts = Proto(100, help="number of points to sample from distribution")
        num_epochs = Proto(70000, help="number of epochs to train")
        num_tasks = Proto(10, help="number of tasks in the inner loop")
        num_grad_steps = Proto(1, help="number of gradient descent steps in the inner loop")
        num_points_sampled = Proto(10, help="effectively the k-shot")
        eval_grad_steps = Proto([0, 1, 10], type=bool, help="the grad steps evaluated with full sample")
        fix_amp = Proto(False, help="controls the sampling, fix the amplitude of the sample distribution if True")

    assert G.npts == 100
    G.npts = 10
    assert G.npts == 10
    assert vars(G) == {'npts': 10, 'num_epochs': 70000, 'num_tasks': 10, 'num_grad_steps': 1,
                       'num_points_sampled': 10, 'fix_amp': False,
                       'eval_grad_steps': [0, 1, 10]}
    assert G._proto is not None, '_proto should exist'

Setting Function Signatures using Python Namespace

sometimes, you have a function with wildcard keyword argument signature. It is annoying to work with such functions because the static type analysis of the IDE doesn’t tell you what needs to go in.

I originally wrote this decorator to help with that case, however the dynamically set function signature won’t show up in the IDE in general. Use this for inspection purposes if you like.

Below si the usage example and the test case:

def test_proto_signature():
    class G(ParamsProto):
        """some parameter proto"""
        n = 1
        npts = Proto(100, help="number of points to sample from distribution")
        ok = True

    def main_demo(**kwargs):
        print('npts = ', kwargs['npts'])
        return kwargs['npts']

    # First way is to use proto_signature decorator. The dynamically generated signature
    # however does not show up in pyCharm. It does however, show during run time.
    import inspect

    assert main_demo(npts=10) == 10
    print("main_demo<Function> signature:", inspect.signature(main_demo))
    assert str(inspect.signature(main_demo)) == "(n=1, npts=100, ok=True)"

To Develop

git clone
cd params_proto
make dev

To test, run the following under both python 3.52 and 3.6.

make test

This make dev command should build the wheel and install it in your current python environment. Take a look at the for details.

To publish, first update the version number, then do:

make publish

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for params-proto, version 2.6.0
Filename, size File type Python version Upload date Hashes
Filename, size params_proto-2.6.0-py3-none-any.whl (13.8 kB) File type Wheel Python version py3 Upload date Hashes View hashes

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN SignalFx SignalFx Supporter DigiCert DigiCert EV certificate StatusPage StatusPage Status page