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0 pointsFreakLegion1y ago0 comments

TypedDicts solve the linting problem, but refactoring tools haven't caught up (unlike e.g. ForwardRef type annotations, which are strings but can be transformed alongside type literals).

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tomjakubowski1y ago

Is there any advantage to using a TypedDict for a record over a dataclass?

FreakLegionOP1y ago

TypedDicts "aren't real" in the sense that they're a compile-time feature, so you're getting typing without any deserialization cost beyond the original JSON. Dataclasses and Pydantic models are slow to construct, so that's not nothing.

This of course means TypeDicts don't give you run-time validation. For that, and for full-blown custom types in general, I tend to favor msgspec Structs: https://jcristharif.com/msgspec/benchmarks.html#json-seriali....

orf1y ago

> Dataclasses and Pydantic models are slow to construct

Citation needed? Pydantic is really quite fast, and you can pass raw JSON responses into it.

It may be slower (depending on the validators or structure), but I’d expect it to be comparably fast to the stdlib JSON module.

newaccountman21y ago

> Citation needed? Pydantic is really quite fast

Pydantic v1 was slow enough for them to write a lot of the core logic in Rust for Pydantic v2, and for the previous sloth to have been an argument people launched against it if you look back at threads on here and Reddit comparing it to other libraries.

FreakLegionOP1y ago

Pydantic's JSON parsing is faster than the built-in module, on par with orjson, but creating model instances and run-time type checking net out to be much slower. I linked msgspec's benchmarks in the previous post.

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tomjakubowski1y ago

Is there any advantage to using a TypedDict for a record over a dataclass?

FreakLegionOP1y ago

orf1y ago

> Dataclasses and Pydantic models are slow to construct

Citation needed? Pydantic is really quite fast, and you can pass raw JSON responses into it.

It may be slower (depending on the validators or structure), but I’d expect it to be comparably fast to the stdlib JSON module.

newaccountman21y ago

> Citation needed? Pydantic is really quite fast

FreakLegionOP1y ago

j / k navigate · click thread line to collapse