Enhancement Proposal: Generalized DI system

[adriangb]

A high-level proposal for enhancements to the DI system.

[adriangb]

I believe tbe original request in #3620 also be made to work by having a dependency scope that goes out of scope before the request is returned (in addition to the default/current which goes out of scope after the request is returned)

[ghandic]

@adriangb does this PR help this issue too? #3953

[adriangb]

@adriangb does this PR help this issue too? #3953

I can't tell just from the description of the issue, but if it is about raising exceptions after yield in dependencies, then yes, this could potentially help certain use cases

[ghandic]

It derives from this issue raised in the discussions where exceptions are raised in the Depends - for instance, pydantic validation errors coming from BaseModel Query parmeters #3426 (reply in thread)

[adriangb]

I think I understand. Truth be told, that seems like a bug in FastAPI exception handling or an unsupported feature, depending on how you look at it. This proposal may help in cleaning up the implementations, which might indirectly help with that issue, but since this proposal doesn't say anything about exception handling, I don't think it directly addresses that issue

[adriangb]

Seems like #3902 and #639 are also related. di is currently able to parallelize both sync and async dependencies: https://github.com/adriangb/di/tree/main/benchmarks

[adriangb]

Relevant discussion: #4035