Value-to-value conversion in Python.
First, let's create a model for conversion. The model can be any class.
For convenience, let's take dataclass:
from dataclasses import dataclass
from convertible import Convertible
@dataclass
class User(Convertible):
name: str
age: intNow User has conversion methods try_from and try_into. But we haven't
implemented any converter. Let's do this.
from typing import Tuple
from convertible import From
class UserFromTuple(From[tuple[str, int], User]):
def try_from(self, value: tuple[str, int]) -> User:
return User(name=value[0], age=value[1])Now we can instantiate User from tuple:
user = User.try_from(("John", 23))
assert user.age == 23We can convert user into another type. Let's define the converter:
# note that User is now the first parameter:
class UserIntoDict(From[User, dict]):
def try_from(self, user: User) -> dict:
return {
"username": user.name,
"age": user.age
}
data = user.try_into(dict)
assert data["username"] == user.nameImplementing From for two Convertible classes automatically provides the
second Convertible with an implementation for try_into:
@dataclass
class Admin(Convertible):
name: str
class AdminFromUser(From[User, Admin]):
def try_from(self, user: User) -> Admin:
return Admin(name=user.name)
# these are equivalent
assert user.try_into(Admin) == Admin.try_from(user)You may need to define converters for types that are not Convertible.
This can be done using the register_converter function:
class IntFromString:
def try_from(self, value: str) -> int:
return int(value)
From[int, str].register_converter(IntFromString)
value = From[int, str].try_from("123")
assert value == 123