fixed type checking errors.

[SKalt]

Resolves #67.

I had to swap @dataclasses for __init__(self, *args) syntax to placate mypy. It isn't ideal, but it was less dumb than other possible workarounds, such as having self.app be a tuple of (app: ASGIApp,).

demonstration of the trouble with @dataclass

from dataclasses import dataclass
from typing import Callable, Dict

Foo = Callable[[Dict[str, str]], int]


def foo(d: Dict[str, str]) -> int:
    return len(list(d.keys()))


@dataclass
class Bar:
    foo: Foo  # mypy thinks the first argument is `self`!

    def run(self, d: Dict[str, str]) -> None:
        print(self.foo(d))
        # Invalid self argument "Bar" to attribute function "foo" with type "Callable[[Dict[str, str]], int]"mypy(error)
        # Too many argumentsmypy(error)


bar = Bar(foo)
bar.run({"a": "1"})  # works, but doesn't pass the type checker


class Baz(object):
    def __init__(self, foo: Foo):
        self.foo = foo  # explicit enough that mypy doesn't think `self.foo` is passed `self`

    def run(self, d: Dict[str, str]) -> None:
        print(self.foo(d))

baz = Baz(foo)
bar.run({"a": "1"})  # works **and** passes type checking

[SKalt]

@ERM : I can see that travis-ci is firing, but I can't see the test results for this PR. I think you'll need to configure either the github webhooks settings or the travisc-ci run itself.

[jordaneremieff]

@SKalt thanks for this! These are definitely some fixes I'd like to get in here - very much appreciate the PR. :)

I'll give this a proper review soon, but looks good so far.

[jordaneremieff]

@SKalt so I looked into the issue with dataclasses to see if there may be a solution that would allow us to keep using them with mypy. I'm thinking rather than refactoring the class syntax that we could try something like changing the ASGIApp definition to use the callback protocol as suggested in python/mypy#5485 (comment):

# mangum/typing.py

from typing_extensions import Protocol

class ASGIApp(Protocol):
    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
        ...

What do you think? My initial testing with this seems to pass the linter and tests fine, though this definition might require some tweaking.

[SKalt]

The only trade-off I see is having to write ``` try: from typing import Protocol # 3.8+ except ImportError: from typing_extensions import Protocol #2.7-3.7 ``` Which I'll say is better than reverting to full-on classes.

…

On Wed, Nov 20, 2019, 01:01 Jordan Eremieff ***@***.***> wrote: @SKalt <https://github.com/SKalt> so I looked into the issue with dataclasses to see if there may be a solution that would allow us to keep using them with mypy. I'm thinking rather than refactoring the class syntax that we could try something like changing the ASGIApp definition to use the callback protocol <https://mypy.readthedocs.io/en/latest/protocols.html#callback-protocols> as suggested in python/mypy#5485 (comment) <python/mypy#5485 (comment)>: # mangum/typing.py class ASGIApp(Protocol): def __call__( self, scope: Scope, receive: Receive, send: Send ) -> typing.Awaitable[None]: ... What do you think? My initial testing with this seems to pass the linter and tests fine. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#68>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACPUNZO7D6K2HE7BJHDTKNLQUTHFNANCNFSM4JOXGGFA> .

[jordaneremieff]

@SKalt Great, let's go ahead with the Protocol solution here (and your proposed import statements for 3.8 support) - thanks.

[SKalt]

did you happen to do your tests on top of my branch? On Wed, Nov 20, 2019 at 8:35 PM Jordan Eremieff <[email protected]> wrote:

…

The only trade-off I see is having to write try: from typing import Protocol # 3.8+ except ImportError: from typing_extensions import Protocol #2.7-3.7 Which I'll say is better than reverting to full-on classes. … <#m_8069571441260918262_> On Wed, Nov 20, 2019, 01:01 Jordan Eremieff *@*.***> wrote: @SKalt <https://github.com/SKalt> https://github.com/SKalt so I looked into the issue with dataclasses to see if there may be a solution that would allow us to keep using them with mypy. I'm thinking rather than refactoring the class syntax that we could try something like changing the ASGIApp definition to use the callback protocol https://mypy.readthedocs.io/en/latest/protocols.html#callback-protocols as suggested in python/mypy#5485 <python/mypy#5485> (comment) <python/mypy#5485 (comment) <python/mypy#5485 (comment)>>: # mangum/typing.py class ASGIApp(Protocol): def *call*( self, scope: Scope, receive: Receive, send: Send ) -> typing.Awaitable[None]: ... What do you think? My initial testing with this seems to pass the linter and tests fine. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#68 <#68>, or unsubscribe https://github.com/notifications/unsubscribe-auth/ACPUNZO7D6K2HE7BJHDTKNLQUTHFNANCNFSM4JOXGGFA . Great, let's go ahead with the Protocol solution here (and your proposed import statements for 3.8 support) - thanks. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#68>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACPUNZLRLAB7V5R4ULZ2JU3QUXQWBANCNFSM4JOXGGFA> .

[jordaneremieff]

did you happen to do your tests on top of my branch? On Wed, Nov 20, 2019 at 8:35 PM Jordan Eremieff [email protected] wrote:
…
The only trade-off I see is having to write try: from typing import Protocol # 3.8+ except ImportError: from typing_extensions import Protocol #2.7-3.7 Which I'll say is better than reverting to full-on classes. … <#m_8069571441260918262_> On Wed, Nov 20, 2019, 01:01 Jordan Eremieff @.***> wrote: @SKalt https://github.com/SKalt https://github.com/SKalt so I looked into the issue with dataclasses to see if there may be a solution that would allow us to keep using them with mypy. I'm thinking rather than refactoring the class syntax that we could try something like changing the ASGIApp definition to use the callback protocol https://mypy.readthedocs.io/en/latest/protocols.html#callback-protocols as suggested in python/mypy#5485 <python/mypy#5485> (comment) <python/mypy#5485 (comment) <python/mypy#5485 (comment)>>: # mangum/typing.py class ASGIApp(Protocol): def call( self, scope: Scope, receive: Receive, send: Send ) -> typing.Awaitable[None]: ... What do you think? My initial testing with this seems to pass the linter and tests fine. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#68 <#68>?email_source=notifications&email_token=ACPUNZO6SSGBSGS7P7NPFXTQUTHFNA5CNFSM4JOXGGFKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEEQ2IEI#issuecomment-555852817>, or unsubscribe https://github.com/notifications/unsubscribe-auth/ACPUNZO7D6K2HE7BJHDTKNLQUTHFNANCNFSM4JOXGGFA . Great, let's go ahead with the Protocol solution here (and your proposed import statements for 3.8 support) - thanks. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#68?email_source=notifications&email_token=ACPUNZPKUVFB6DEYZGSOWOLQUXQWBA5CNFSM4JOXGGFKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEEX7BEI#issuecomment-556789905>, or unsubscribe https://github.com/notifications/unsubscribe-auth/ACPUNZLRLAB7V5R4ULZ2JU3QUXQWBANCNFSM4JOXGGFA .

Yes. What I did to test was revert the Mangum adapter class back to a dataclass and included the protocol type in mangum/typing.py on this branch.

[jordaneremieff]

Thanks!