Installation

pip install easy_flags

Basic example

foo.py

from easy_flags import SimpleConfig

class MyConfig(SimpleConfig):
    int_val = 4
    bool_val = True
    with_doc = 0.4, 'some docs'  # type: float
    without_default = None, int, 'another docs'  # type: bool

if __name__ == '__main__':
    # command line arguments will be parsed after ::define call
    c = MyConfig().define().print()
    print('bool_val:', c.bool_val)

Run:

$ python foo.py

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|  bool_val        : True
|  int_val         : 4
|  with_doc        : 0.4
|  without_default : None
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bool_val: True

Process finished with exit code 0


$ python foo.py -h

usage: foo.py [-h] [--bool_val | --no-bool_val] [--int_val INT_VAL]
                     [--with_doc WITH_DOC] [--without_default WITHOUT_DEFAULT]

optional arguments:
  -h, --help            show this help message and exit
  --bool_val            bool, default: True
  --no-bool_val
  --int_val INT_VAL     int, default: 4
  --with_doc WITH_DOC   float, default: 0.4 - some docs
  --without_default WITHOUT_DEFAULT
                        int, default: None - another docs

Alternative definition

from easy_flags import Config, IntField, BoolField, FloatField

class MyConfig(Config):
    int_val = IntField(4)
    bool_val = BoolField(default=True)
    with_doc = FloatField(0.4, 'some docs')
    without_default = IntField(doc='another docs')

Reusabillity

from easy_flags import Config

class ModelConfig(Config):
    layers = 4
    time_steps = 256
    cell_size = 256
    dropout = 1.0

# same as model config + additional parameters
class TrainingConfig(ModelConfig):
    lr = 0.001
    epochs = 10000
    dropout = 0.9  # change parent arg

Docstrings

If you want to add help message for field (which will be displayed if you run script with --help flag), then you need to add it after flags’ default value:

class ExampleConfig(BaseConfig):
    foo = 5.0, 'Some float field.'
    bar = 'field with only default docstring'

./script.py --help
usage: test_base.py [-h] [--bar BAR] [--foo FOO]

optional arguments:
  -h, --help  show this help message and exit
  --bar BAR   String field, default='field with default docstring'.
  --foo FOO   Float field, default=5.0. Some float field.

Booleans

Boolean flag with spefied in config name will set destination value to True, and the same flag prefixed with ‘no-’ will set value to False

class ExampleConfig(BaseConfig):
    cache = True
    f = False

./script --cache -f
# cache=True, f=True

./script --no-cache --no-f
# cache=False, f=False

Short flag names

If flag name consists only from one letter then it can be specified with one dash instead of two.

class ExampleConfig(BaseConfig):
    e = 100, 'number of epochs'
    b = True

./train.py -e 42 -b
# also valid with two dashes
./train.py --e 42 --b
./train.py --e 42 --no-b

Specify type for tuples

class ExampleConfig(BaseConfig):
    lr = 0.001, 'learning rate'
conf = ExampleConfig()
conf.define()

In example above pre-defined conf.lr is obviously not a float and some static checkers after typec hecking will make a warning that they expected a float as argument for some function but got tuple instead. Fortunately we can help IDE by adding special comment with proper after-define type:

class ExampleConfig(BaseConfig):
    lr = 0.001, 'learning rate'  # type: float