Water

Like fire

This python library parses classes so that they can be executed as commands.
In contrast with fire, there is no "automatic" type casting -- the type casting is 100% based on type hints.

Type casting

When calling execute_command the values passed in the command get casted to the annotated types on the function signature.

Supported types:

• int, float
• bool: the strings ['true', '1', 't', 'y'] are considered true.
• lists, tuples: input is split by comma (,) and each element is casted independently.
• enum
• Union[]: gets casted to all options in order, first success is returned.
  • Optional[type] is Union[type, NoneType]
• water.Flag: flag, only denotes the switch was present.
• water.Repeated[T]: Effectively the same as List[T] but allows flags to be repeated and values will be concatenated

Utilities

• exclusive_flags forbids certain flag combinations to be used at the same time.
  • If --a and --b are exclusive, executing command --a --b causes an error.
• required_together requires certain flag combinations to be used at the same time.
  • If --a and --b are required together, executing command --a or command --b causes an error.

Examples

Type casting

class Math1:

    def add_list(self, items: Optional[List[int]] = None):
        if not items:
            return 0
        return sum(items)

    def add_numbers(self, number: Repeated[int]):
        return sum(number)

# `items` casted to a list of `int`
res = execute_command(Math1, 'add_list --items 1,2,3')
assert res == 6

# `items` casted to a list of `int`, even though there is only one entry
res = execute_command(Math1, 'add_list --items 1')
assert res == 1

# `number` casted to a list of `int`, even though there is only one entry
res = execute_command(Math1, 'add_numbers --number 1')
assert res == 1

# `number` casted to a list of `int`, even though there is only one entry
res = execute_command(Math1, 'add_numbers --number 1 --number 2')
assert res == 3

Nested commands

class NestedObj:
    class Inside1:
        def fn1(self, number: int):
            return number

res = execute_command(NestedObj, 'Inside1 fn1 --number 1')
assert res == 1

Testing

Python3.9, 3.11:

docker build -f dockerfiles/3.9-Dockerfile .
docker build -f dockerfiles/3.11-Dockerfile .

Development

poetry run pytest

Releasing

poetry publish --build --username $PYPI_USERNAME --password $PYPI_PASSWORD