Trait AttributeResultExt

Source

pub trait AttributeResultExt<O> {
    // Required method
    fn attribute(self, attr: QualName) -> Result<O, ElementError>;
}

Expand description

Helper for converting Result<O, E> into Result<O, ElementError>

A ElementError requires a QualName that corresponds to the attribute to which the error refers, plus the actual ValueErrorKind that describes the error. However, parsing functions for attribute value types will want to return their own kind of error, instead of ValueErrorKind. If that particular error type has an impl From<FooError> for ValueErrorKind, then this trait helps assign attribute values in set_atts() methods as follows:

fn parse_foo(value: &str) -> Result<(), FooError>

// It is assumed that there is an impl From<FooError> for ValueErrorKind
let result = parse_foo("value").attribute(attr);
assert!(result.is_err());

The call to .attribute(attr) converts the Result from parse_foo() into a full ElementError with the provided attr.