type-enforced 0.0.8

A type enforcer for python type annotations

Type Enforced

Enforce types in python functions

Setup

Make sure you have Python 3.6.x (or higher) installed on your system. You can download it here.

Installation

pip install type_enforced

Getting Started

type_enforcer contains a basic Enforcer wrapper that can be used to enforce most basic python typing hints.

type_enforcer currently supports all single level python types, single level class instances and classes themselves. For example, you can force an input to be an int or an instance of the self defined MyClass, but not a vector of the format list(int). In this case, when using type_enforcer, you would only pass the format list and would not validate that the content of the list was indeed integers.

You can pass multiple types in brackets to validate one of multiple types. For example, you could validate an input was an int or a float with [int, float].

Non specified types for variables are not enforced.

Input and return typing are both supported.

Basic Usage

import type_enforced

@type_enforced.Enforcer
def my_fn(a: int , b: [int, str] =2, c: int =3) -> None:
    pass

Interactive Example

>>> import type_enforced
>>> @type_enforced.Enforcer
... def my_fn(a: int , b: [int, str] =2, c: int =3) -> None:
...     pass
...
>>> my_fn(a=1, b=2, c=3)
>>> my_fn(a=1, b='2', c=3)
>>> my_fn(a='a', b=2, c=3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/conmak/development/personal/type_enforced/type_enforced/enforcer.py", line 47, in __call__
    return self.__validate_types__(*args, **kwargs)
  File "/home/conmak/development/personal/type_enforced/type_enforced/enforcer.py", line 83, in __validate_types__
    self.__check_type__(assigned_vars.get(key), value, key)
  File "/home/conmak/development/personal/type_enforced/type_enforced/enforcer.py", line 56, in __check_type__
    self.__exception__(
  File "/home/conmak/development/personal/type_enforced/type_enforced/enforcer.py", line 37, in __exception__
    raise Exception(f"({self.__fn__.__qualname__}): {message}")
Exception: (my_fn): Type mismatch for typed function (my_fn) with `a`. Expected one of the following `[<class 'int'>]` but got `<class 'str'>` instead.

Class and Method Use

Type enforcer can be applied to methods individually:

import type_enforced

class my_class:
    @type_enforced.Enforcer
    def my_fn(self, b:int):
        pass

You can also enforce all typing for all methods in a class by decorating the class itself.

import type_enforced

@type_enforced.Enforcer
class my_class:
    def my_fn(self, b:int):
        pass

    def my_other_fn(self, a: int, b: [int, str]):
      pass

You can also enforce types on staticmethods and classmethods

import type_enforced

@type_enforced.Enforcer
class my_class:
    @classmethod
    def my_fn(self, b:int):
        pass

    @staticmethod
    def my_other_fn(a: int, b: [int, str]):
      pass

Validate class instances and classes

Type enforcer can enforce class instances and classes easily. There are a few caveats between the two.

To enforce a class instance, simply pass the class itself as a type hint:

import type_enforced

class Foo():
    def __init__(self) -> None:
        pass

@type_enforced.Enforcer
class my_class():
    def __init__(self, object: Foo) -> None:
        self.object = object

x=my_class(Foo()) # Works great!
y=my_class(Foo) # Fails!

Notice how an initialized class instance Foo() must be passed for the enforcer to not raise an exception.

To enforce an uninitialized class object use typing.Type[classHere] on the class to enforce inputs to be an uninitialized class:

import type_enforced
import typing

class Foo():
    def __init__(self) -> None:
        pass

@type_enforced.Enforcer
class my_class():
    def __init__(self, object_class: typing.Type[Foo]) -> None:
        self.object = object_class()

y=my_class(Foo) # Works great!
x=my_class(Foo()) # Fails