Enum AllowableValue 

pub enum AllowableValue {
    Any,
    Empty,
    Effective(InterpretedValue),
    Implied(&'static str),
}

Allowable values for the attribute.

Variants

Any

Any value is accepted.

Empty

Indicates the attribute doesn’t require an explicit value. The attribute is simply turned on by being set.

Effective(InterpretedValue)

In some cases, an empty value is interpreted by the processor as one of the allowable non-empty values. This effective value is prefixed with an equals sign and enclosed in square brackets (e.g., [=auto]). An attribute reference will resolve to an empty value rather than the effective value.

Implied(&'static str)

Built-in attributes that are not set may have an implied value. The implied value is enclosed in parentheses (e.g., (attributes)). An implied value can’t be resolved using an attribute reference.

Trait Implementations

impl Clone for AllowableValue

fn clone(&self) -> AllowableValue

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AllowableValue

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for AllowableValue

fn eq(&self, other: &AllowableValue) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for AllowableValue

impl StructuralPartialEq for AllowableValue