I want to use type hint with string as a key and different classes as a value in a dictionary like below.

configurations: Dict[str, what_class??] = {
    "dev": Dev,
    "product": Product,
    "test": Test,
}

The classes Dev, Product, Test inherit from a base class "Parent".

class Parent:
    pass

class Dev(Parent):
    pass

class Product(Parent):
    pass

class Test(Parent):
    pass

What is the best way to do the type hint for this?

Do I need to set just "Any" as their type?

CodePudding user response：

Depends on how accurate you want your hints to be,

1. Use the parent class

configurations: Dict[str, Parent] = {
    "dev": Dev,
    "product": Product,
    "test": Test,
}

2. Specify the classes in a union

from typing import Union
configurations: Dict[str, Union[Dev, Product, Test]] = {
    "dev": Dev,
    "product": Product,
    "test": Test,
}

3. Create a TypedDict type for this specific dict

from typing import TypedDict

class EnvDict(TypedDict):
    dev: Dev
    product: Product
    test: Test
    
configurations: EnvDict = {
    "dev": Dev,
    "product": Product,
    "test": Test,
}

CodePudding user response：

In your case, creating a dictionary without using type hints seems the most optimal solution, as you can access all classes directly from the dict variable configurations, using the proper string key value:

class Parent:
    pass

class Dev(Parent):
    pass

class Product(Parent):
    pass

class Test(Parent):
    pass

configurations = {
    "dev": Dev,
    "product": Product,
    "test": Test,
}

print(configurations)

Output:

{'dev': <class '__main__.Dev'>, 'product': <class '__main__.Product'>, 'test': <class '__main__.Test'>}

Also, using the Parent class works well if you still want to use type hints:

import typing
class Parent:
    pass

class Dev(Parent):
    pass

class Product(Parent):
    pass

class Test(Parent):
    pass

configurations: typing.Dict[str, Parent] = {
    "dev": Dev,
    "product": Product,
    "test": Test,
}
print(configurations)

It outputs the same dictionary as the above code.