Add enum namespacing to the Guide. #19616
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| Notice that we need both the enum name and the variant name: `StringResult::StringOK`, but | ||
| we didn't need to with `Ordering`, we just said `Greater` rather than `Ordering::Greater`. | ||
| There's a reason: the Rust prelude imports the variants of `Ordering` as well as the enum | ||
| itself. We can use the `use` keyword to do something similar with `StringResult`: |
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The current use of Ordering the prelude is currently a subject of a bit of debate (rust-lang/rfcs#497, rust-lang/rfcs#504), would it be possible to write this without referencing the prelude or Ordering at all?
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I would love to have it removed, but until then, the guide is still deficient. What's the timeline on the RFC getting accepted? I'd rather not have the guide be wrong for weeks.
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Oh I was thinking that we could accept this now if an example other than Ordering was used. Perhaps Option which will likely always be in the prelude?
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I chose Ordering for a few reasons. One is that it's a classic pattern in C which is different than in Rust. Secondly because it fits nicely into the classic guessing game example. Removing the Ordering example invovles changing almost the first half of the guide.
We do talk about Option in the section with variants, which we haven't gotten to yet at this point, IIRC. Or at least, that's why we do Ordering first: enum without variants, then one with.
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Ok! We can revise slightly as necessary as the prelude changes later on in that case.
| @@ -1160,6 +1160,55 @@ Where a `StringResult` is either an `StringOK`, with the result of a computation | |||
| `ErrorReason` with a `String` explaining what caused the computation to fail. These kinds of | |||
| `enum`s are actually very useful and are even part of the standard library. | |||
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| Enum variants are namespaced under the enum names. For example, here is an example of using | |||
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Just a wee tidbit - I think it might be unnecessary to use "example" twice in
For example, here is an example...
Perhaps this sentence could just be "Here is an example using our StringResult:" ?
Closes #19556.