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0 pointscornstalks5y ago0 comments

> `as` is not considered idiomatic in Rust code

Yes it is. It's used all the time. There's a reason as_conversions defaults to Allow in clippy.

Of course, there are lots of situations where `as` is the wrong tool for the job, but I think it's a bit of a stretch to call `as` "not idiomatic". It's perfectly idiomatic in lots of situations.

Whether or not it should be idiomatic is a separate question.

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kibwen5y ago

I think the parent poster is jumping the gun, but it is true that the flaws in `as` have been acknowledged for a long time and alternatives for specific use cases have been regularly introduced in order to reduce its use where possible. Giving it dedicated syntax might be one of the bigger warts of Rust 1.0: it may be the most convenient way to cast between primitive types, but it's often not the best way.

IOW, is it currently unidiomatic? No, code reviewers won't generally look sideways at it. But it's certainly getting less idiomatic over time, and that trend doesn't seem likely to stop soon.

nullc5y ago

Well or being a temporal throwback instead of gun jumping. The initial handling of integer overflow was another such decision in my view, but it was ultimately reversed.

fluffy875y ago

Your claim that “as” being used is incompatible with it being unidiomatic is false.

The docs, the reference, and the RFCs all regards “as” as a mistake that should not be used, and _many_ features have been introduced over the years to reduce the cases in which “as” is the only alternative.

There are cases in which there is currently no alternative, so people “must” use “as”. This does not imply that it is idiomatic to do so.

erk__5y ago

But clippy will also scream at you if you convert a larger type to a smaller one.

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