ref: Event Type

[szokeasaurusrex]

Implements type hinting for Event via a TypedDict. This PR mainly adjusts type hints; however, there are also some minor code changes to make the code type-safe following the new changes.

Some items in the Event could have their types expanded by being defined as TypedDicts themselves. These items have been indicated with TODO comments.

Fixes GH-2357

[szokeasaurusrex]

Will need to either:

• Rebase on 2.0 branch
• Move to functional TypedDict syntax

[antonpirker]

Great work @szokeasaurusrex looks great!
I have a few questions.

[szokeasaurusrex]

Thank you for the feedback! I replied to your comments and made some changes

[szokeasaurusrex]

Added for same reason as above, and similarly we don't need it any more

[antonpirker]

Typing rocks!

[ods]

Looks like a breaking change.

Is there a way to use functions with Event type arguments without type: ignore or erasing type with Any? And example from our flow that worked before this:

def before_send(event: dict[str, Any], _: dict[str, Any]) -> dict[str, Any]:
    for frame in iter_event_frames(event):
        do_smth(frame)
    return event

Now checking with mypy gives an errors:

error: Argument 1 to "iter_event_frames" has incompatible type "dict[str, Any]"; expected "Event"  [arg-type]

I'd be happy to switch to using Event typed dict, but 1) it's not publicly exposed, 2) it's defined behind if TYPE_CHECKING which is not always acceptable.

[szokeasaurusrex]

Hi @ods, thank you for reaching out!

I'd be happy to switch to using Event typed dict, but 1) it's not publicly exposed, 2) it's defined behind if TYPE_CHECKING which is not always acceptable.

We released 1.43.0 earlier today, which re-exports Event as a public type in sentry_sdk.types (see #2829).

However, because we need to maintain compatibility with old Python versions, we need to define the Event type behind an if TYPE_CHECKING block. You should be able, however, to use the type hint in your code by importing Event from within an if TYPE_CHECKING block, and then enclosing the type in quotes, like so:

from typing import TYPE_CHECKING
if TYPE_CHECKING:
    from sentry_sdk.typing import Event

def before_send(event: "Event", _: dict[str, Any]) -> "Event":
    ...

Looks like a breaking change.

I understand your frustration, and while I certainly believe we made a mistake by using a private type on publicly exposed functions, our reasoning with this change is that it is not breaking because it only affects type hints, which are not evaluated at runtime and not enforced by the Python language. The code is fully backwards-compatible at runtime, and the runtime public API has remained the same as previously – any code written before this change will continue to work the same now after the change.

[ods]

Thanks for quick response!

However, because we need to maintain compatibility with old Python versions, we need to define the Event type behind an if TYPE_CHECKING block.

Strictly speaking it's not the only option. The type can be defined unconditionally, but imported inside if TYPE_CHECKING block. This way it won't break in old Python versions, because module is not imported.

Ok, anyway we have to find some workaround.

[szokeasaurusrex]

Strictly speaking it's not the only option. The type can be defined unconditionally, but imported inside if TYPE_CHECKING block. This way it won't break in old Python versions, because module is not imported.

This is a good idea! I can certainly look into implementing a conditional import that ensures Event is always defined.