#[non_exhaustive]
pub enum MessageSystemAttributeNameForSends {
    AwsTraceHeader,
    Unknown(UnknownVariantValue),
}
Expand description

When writing a match expression against MessageSystemAttributeNameForSends, it is important to ensure your code is forward-compatible. That is, if a match arm handles a case for a feature that is supported by the service but has not been represented as an enum variant in a current version of SDK, your code should continue to work when you upgrade SDK to a future version in which the enum does include a variant for that feature.

Here is an example of how you can make a match expression forward-compatible:

# let messagesystemattributenameforsends = unimplemented!();
match messagesystemattributenameforsends {
    MessageSystemAttributeNameForSends::AwsTraceHeader => { /* ... */ },
    other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
    _ => { /* ... */ },
}

The above code demonstrates that when messagesystemattributenameforsends represents NewFeature, the execution path will lead to the second last match arm, even though the enum does not contain a variant MessageSystemAttributeNameForSends::NewFeature in the current version of SDK. The reason is that the variable other, created by the @ operator, is bound to MessageSystemAttributeNameForSends::Unknown(UnknownVariantValue("NewFeature".to_owned())) and calling as_str on it yields "NewFeature". This match expression is forward-compatible when executed with a newer version of SDK where the variant MessageSystemAttributeNameForSends::NewFeature is defined. Specifically, when messagesystemattributenameforsends represents NewFeature, the execution path will hit the second last match arm as before by virtue of calling as_str on MessageSystemAttributeNameForSends::NewFeature also yielding "NewFeature".

Explicitly matching on the Unknown variant should be avoided for two reasons:

  • The inner data UnknownVariantValue is opaque, and no further information can be extracted.
  • It might inadvertently shadow other intended match arms.

Variants (Non-exhaustive)§

This enum is marked as non-exhaustive
Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.
§

AwsTraceHeader

§

Unknown(UnknownVariantValue)

Unknown contains new variants that have been added since this code was generated.

Implementations§

Returns the &str value of the enum member.

Returns all the &str values of the enum members.

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