hintcast

Decorators that allow for automatic type-casting of arguments for a function or strict enforcement of type hints.

Usage Summary

Import whatever decorators you want with an import statement like from hintcast import cast_hints, strict_hints.

Casting Types

• To add automated type-casting to your function/method, use the @cast_hints decorator for your method. If a type cannot be cast, a warning will be logged.
• To attempt to cast but raise a TypeError exception if unable to, pass the keyword argument "strict". E.g. @cast_hints(strict=True).
• To pass None values without casting, pass the keyword argument "cast_none". E.g. @cast_hints(cast_none=False).

Enforcing strict types

• You can also use the @strict_hints decorator. This will NOT attempt to cast the types, but will raise a ValueError if a type not matching your hint is passed.

Usage Examples

Casting Types

from hintcast import cast_hints

@cast_hints
def add_two(num: int, text: str):
    print(repr(num+2))
    print(repr(text+"2"))

Output

>>> add_two("3", 3)
5
'32'
>>> add_two("3", None)
5
'None2'

Casting types without casting NoneType

from hintcast import cast_hints

@cast_hints(cast_none=False)
def add_two(num: int, text: str):
  print(repr(num+2))
  print(repr(text+"2"))

Output

>>> add_two("3", 3)
5
'32'
>>> add_two("3", None)
5
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

Casting types and raising TypeError when type could not be cast

from hintcast import cast_hints

@cast_hints(strict=True)
def add_two(num: int, text: str):
  print(repr(num+2))
  print(repr(tex+"2"))

Output

>>> add_two("3", 3)
5
'32'
>>> add_two("test", 3)
TypeError: Could not convert num to <class 'int'>. invalid literal for int() with base 10: 'test'

Enforcing strict typing without casting

from hintcast import strict_hints

@strict_hints
def add_two(num: int, text: str):
  print(repr(num+2))
  print(repr(text+"2"))

Output

>>> add_two("3", 3)
TypeError: num is not of type <class 'int'>
>>> add_two(3, 3)
TypeError: text is not of type <class 'str'>

Future Development Plans

• Test support for all primitive types
• Add support for checking function return type hints
• Add support for built-in non-primitive data structures such as arrays, lists, etc.
• Add support for hinting of types within lists, dictionaries, etc.
• Add ability to enforce typing project-wide

When all of the functionality above has been implemented and tested, the version number will be incremented to 1.0.0 and this project will leave beta status.