typediterable

typediterable is a simple python package for the actual typing of each element of an iterable with type hint notation.

Install

pip install git+ssh://git@github.com/osoken/typediterable.git

Features and Examples

Actual Typing with Type Hint Notation

The following example shows how the main component typediterable.TypedIterable works:

from dataclasses import dataclass
from typediterable import TypedIterable

@dataclass
class User:
    id: int
    name: str

raw_data = [{"id": 0, "name": "Alice"}, {"id": 1, "name": "Bob"}]
for d in TypedIterable[User](raw_data):
    assert isinstance(d, User)

It is equivalent to write:

from dataclasses import dataclass
from typediterable import TypedIterable

@dataclass
class User:
    id: int
    name: str

raw_data = [{"id": 0, "name": "Alice"}, {"id": 1, "name": "Bob"}]
for d in (User(**d) for d in raw_data):
    assert isinstance(d, User)

Error Handling

typediterable.TypedIterable also has the error handling feature.

from dataclasses import dataclass
from typediterable import TypedIterable
from collections.abc import Mapping
from typing import Union

@dataclass
class User:
    id: int
    name: str

def error_handler(d: Mapping[str, Union[int, str]], i: int, e: Exception) -> None:
    print(f"{i}th element `{d}` is invalid due to the following error: {e}")

raw_data = [{"id": 0, "name": "Alice"}, {"name": "lack of id"}, {"id": 1, "name": "Bob"}]
for d in TypedIterable[User](raw_data, on_error=error_handler):
    assert isinstance(d, User)

The above example prints the following string:

1th element `{'name': 'lack of id'}` is invalid due to the following error: User.__init__() missing 1 required positional argument: 'id'

and it doesn't stop iterating. The example is equivalent to write:

from dataclasses import dataclass
from typediterable import TypedIterable
from collections.abc import Mapping
from typing import Union

@dataclass
class User:
    id: int
    name: str

raw_data = [{"id": 0, "name": "Alice"}, {"name": "lack of id"}, {"id": 1, "name": "Bob"}]
for i, raw_d in enumerate(raw_data):
    try:
        d = User(**raw_d)
    except Exception as e:
        print(f"{i}th element `{raw_d}` is invalid due to the following error: {e}")
    assert isinstance(d, User)

Automatic Unpacking Arguments

typediterable.TypedIterable checks the signature and automatically unpacks the arguments. For functions which takes multiple positional arguments or multiple keyword arguments, such as dataclass and pydantic.BaseModel, it unpacks just like the above example. If the function is single-argument, no unpacking is done.

from typediterable import TypedIterable

raw_data = ["1", "2", "3", "4"]
for d in TypedIterable[int](raw_data):
    assert isinstance(d, int)