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Value implementation for `Option<T> where T: Value #878

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Value implementation for `Option<T> where T: Value #878

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4996eb3
lifetime error
akshatagarwl Aug 3, 2020
afe04fd
fix lifetime mismatch
hawkw Aug 5, 2020
eefcfc0
Merge pull request #1 from tokio-rs/eliza/humancalico/option
akshatagarwl Aug 5, 2020
2756881
cannot invoke record_option on a trait object
akshatagarwl Aug 17, 2020
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19 changes: 19 additions & 0 deletions tracing-core/src/field.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,14 @@ pub trait Visit {

/// Visit a value implementing `fmt::Debug`.
fn record_debug(&mut self, field: &Field, value: &dyn fmt::Debug);

/// Visit an Option
fn record_option(&mut self, field: &Field, value: Option<&(dyn Value + 'static)>) {
if let Some(inner_value) = value {
self.record_debug(field, &inner_value)
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I don't think this implements the recording of the interior type using the appropriate type-specific record_* method as described in the linked task.

You probably want to call the record method on the inner_value.

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Yup, that's right.

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Is this right inner_value.record(field, self)?

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Is this right inner_value.record(field, self)?

Yeah, that's right.

} else {
}
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Can this else { } be removed if we aren't going to do anything with it? If a serializer cares about the lack of a value they can always override this method and do a match themselves.

}
}

/// A field value of an erased type.
Expand Down Expand Up @@ -441,6 +449,15 @@ impl<'a> Value for fmt::Arguments<'a> {
}
}

impl<T> Value for Option<T>
where
T: Value + 'static,
{
fn record(&self, key: &Field, visitor: &mut dyn Visit) {
visitor.record_option(key, self.as_ref().map(|v| v as &dyn Value))
}
}

impl fmt::Debug for dyn Value {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// We are only going to be recording the field value, so we don't
Expand Down Expand Up @@ -476,6 +493,8 @@ impl fmt::Display for dyn Value {
}
}

impl<T> crate::sealed::Sealed for Option<T> {}

// ===== impl DisplayValue =====

impl<T: fmt::Display> crate::sealed::Sealed for DisplayValue<T> {}
Expand Down