aio-libs
Feature request: in the server, modifying the response headers after they have been sent should raise
Simple feature: I think after the response has been prepared (ie after the headers are sent back to the client), the Response.headers object should become a read-only dict (ie a CIMultiDictProxy), so that it cannot be modified.
Would you accept a patch doing this?
I have no strong opinion. It makes sense but mutation of attribute type sounds weird from type hinting perspective.
I agree that the type should stay the same.
Ideally, the response.headers object should be a CIMultiDict, but it should raise exceptions when it is mutated after the headers are sent. Replacing the object with a CIMultiDictProxy achieves that, but will give poor error messages to the users, and breaks the type-hinting. Would you prefer an approach that set headers to be a ResponseHeader object, extending CIMultiDict but with an option to raise an explicit error when trying to use __setitem__, add, pop, popall, … The downside to this is that we will have to maintain here the list of "mutating methods" that are forbidden after the response is sent
As an option, we can use multidict's version number: store it on headers sending and compare with the current value on exiting from web-handler. If numbers are different -- raise a warning or something like this. Not ideal (no stack trace pointing on the bad code) but better than nothing.
I think not providing the right stacktrace is a deal breaker, especially when we could provide it. Using a warning instead of making this an error immediately is a good idea of course, to avoid a breaking change
On Tue, 4 Sep 2018 at 15:01, Andrew Svetlov [email protected] wrote:
As an option, we can use multidict's version number: store it on headers sending and compare with the current value on exiting from web-handler. If numbers are different -- raise a warning or something like this. Not ideal (no stack trace pointing on the bad code) but better than nothing.
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