com2ann

Tool for translation of type comments to type annotations in Python.

The tool requires Python 3.8 to run. But the supported target code version is Python 3.4+ (can be specified with --python-minor-version).

Currently, the tool translates function and assignment type comments to type annotations. For example this code:

from typing import Optional, Final

MAX_LEVEL = 80  # type: Final

class Template:
    default = None  # type: Optional[str]

    def apply(self, value, **opts):
        # type (str, **bool) -> str
        ...

will be translated to:

from typing import Optional, Final

MAX_LEVEL: Final = 80

class Template:
    default: Optional[str] = None

    def apply(self, value: str, **opts: str) -> str:
        ...

The philosophy of the tool is to be minimally invasive, and preserve original formatting as much as possible. This is why the tool doesn't use un-parse.

The only (optional) formatting code modification is wrapping long function signatures. To specify the maximal length, use --wrap-signatures MAX_LENGTH. The signatures are wrapped one argument per line (after each comma), for example:

    def apply(self,
              value: str,
              **opts: str) -> str:
        ...

For working with stubs, there are two additional options for assignments: --drop-ellipsis and --drop-none. They will result in omitting the redundant right hand sides. For example, this:

var = ...  # type: List[int]
class Test:
    attr = None  # type: str

will be translated with such options to:

var: List[int]
class Test:
    attr: str