Build Status Checked with mypy

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