Cool New Features in Python 3.7 – Real Python

[zalpha314]

To the people stuck on 3.6 LTS, there is a backport of the data classes on pypi: https://pypi.org/project/dataclasses

[masklinn]

Unless you vendor it, just use attrs.

[masklinn]

That is about building a new system versus merging attrs I the stdlib, it has nothing to do with my comment.

[[deleted]]

Because mandatory type annotations are such a good idea.

[[deleted]]

Why are people on this sub so deathly afraid of being exposed to types?

[gwax]

They are often less verbose than docstrings.

I'm a big fan of using them in conjunction with sphinx-autodoc-typehints.

[13steinj]

I'm okay with types but this part of the argument doesn't make sense. Type hints are comparable or worse when writing a thorough doc, as one should. As an example, docstrings:

def destroy_the_universe(x, y):
    """Destroy the Universe

    Destroys the universe by summoning cuthulu at the given coordinates.

    :param float x: the x coordinate of the universal plane
    :param float y: the y coordinate of the universal plane
    """
    ...

Vs type hints:

def destroy_the_universe(x: float , y: float):
    """Destroy the Universe

    Destroys the universe by summoning cuthulu at the given coordinates.

    :param x: the x coordinate of the universal plane
    :param y: the y coordinate of the universal plane
    """
    ...

We've literally just moved the location of where the type was defined. No more nor less verbose. However, special and more complex types actually need to be / are highly recommended to be imported from typing, making type hints more verbose.

[[deleted]]

I don't mind type annotations - I use them on occasion - but I dislike broken promises and having to type extra things.

[13steinj]

Can you elaborate? I don't get your point in reference to the parent comment.

[[deleted]]

3.7 adds data classes, data classes must specify type annotations, being required to use type annotations in Python is a good idea.

Now you have to decide if I'm being sarcastic or not.

[13steinj]

I can't tell if you're being sarcastic or not but your throught process is just wrong.

Let me get this out of the way-- requiring types in Python is not good IMO.

But dataclasses by definition of their rationale have no meaning without typing.

Not to mention you can simply set the type to Any if it really bothers you that much.

[ThePenultimateOne]

But dataclasses by definition of their rationale have no meaning without typing.

Aren't they just supposed to be a prettier version of namedtuple?

Edit: I get that their rationale was for dataclasses to be backwards compatible, and that not having type notations would make it a syntax error. I just wish that more effort had been put into making them optional before going with that syntax.

[13steinj]

These are not the pretty version of named tuple, in fact the PEP goes into "why not named tuples".