Added the or_default method to EitherOrBoth
#538
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Looks good to me. Maybe we can collect all the |
Thanks! So how would we do that if there are different bounds on the generics in different |
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Put the bounds on the methods, rather than the block. |
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Oh that makes sense. I'll add another commit which does that. |
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bors r+ |
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Dec 29, 2021
593: EitherOrBoth: Add or and or_else methods to simplify getting default values r=phimuemue a=carl-anders
## Introducing `or` and `or_else` methods to `EitherOrBoth`
This feature reduces the amount of code required to get specific default values when using EitherOrBoth.
An example of the current way of using `zip_longest` with custom default values:
```rust
let a = (0..=4).into_iter();
let b = (0..=2).into_iter();
let c = a.zip_longest(b).map(|e| match e {
EitherOrBoth::Both(l, r) => (l, r),
EitherOrBoth::Left(l) => (l, 2),
EitherOrBoth::Right(r) => (4, r),
});
// c will now contain an iterator with (0,0), (1,1), (2,2), (3,2), (4,2).
```
An example with the proposed `or` method:
```rust
let a = (0..=4).into_iter();
let b = (0..=2).into_iter();
let c = a.zip_longest(b).map(|e| e.or(4, 2));
// c will now contain an iterator with (0,0), (1,1), (2,2), (3,2), (4,2).
```
I have also included the `or_else` method which does the same but with closures.
## Contribute questions
> Include tests for your new feature, preferably a QuickCheck test
There are no tests for the other `EitherOrBoth` methods, so I was unsure how to place them. However, I have added **DocTest**'s to both methods. These examples allows for easier to understand documentation, and also tests the validity of the methods.
> For new features, please first consider filing a PR to rust-lang/rust
The EitherOrBoth struct does not exist in rust std library.
## Concerns
The naming is slightly inconsistent when compared to rust's `std::Option`, considering the naming from there the added methods should be named `unwrap_or` and `unwrap_or_else`.
However, this would then become inconsistent with the existing method `EitherOrBoth::or_default`. Which is why I went with the chosen names.
I can change the method names if needed, but then we should consider changing `or_default` too.
## P.S.
The `CHANGELOG.md` file has the text `Add EitherOrBoth::or_default (#583)`. This number is wrong, it should be #538.
Co-authored-by: Carl Andersson <carl@carlandersson.net>
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This commit is motivated by the context explained in issue #537
Allows for doing things like padding out an iterator with a default value while the other one is consumed.