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Carol (Nichols || Goulding) 2016-12-28 20:25:34 -05:00
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src/ch09-02-recoverable-errors-with-result.md
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@ -236,10 +236,11 @@ The condition `if error.kind() == ErrorKind::NotFound` is called a *match
guard*: it's an extra condition on a `match` arm that further refines the arm's
pattern. This condition must be true in order for that arm's code to get run;
otherwise, the pattern matching will move on to consider the next arm in the
`match`. The `ref` in the pattern is needed so that the `error` is
not moved into the guard condition but is merely referenced by it.
<!-- Hm, how come we use `ref` as the syntax here and not &? -->
`match`. The `ref` in the pattern is needed so that the `error` is not moved
into the guard condition but is merely referenced by it. The reason `ref` is
used to take a reference in a pattern instead of `&` will be covered in detail
in Chapter XX. In short, in the context of a pattern, `&` matches a reference
and give us its value, but `ref` matches a value and gives us a reference to it.
The condition we want to check in the match guard is whether the value returned
by `error.kind()` is the `NotFound` variant of the `ErrorKind` enum. If it is,