Trait ScopeAttr

pub trait ScopeAttr {
    // Required methods
    fn path(&self) -> SimplePath;
    fn apply(&self, attr: Attribute, scope: &mut Scope) -> Result<()>;

    // Provided method
    fn support_repetition(&self) -> bool { ... }
}

Attribute rule for Scope

Rules are matched via a path, e.g. &["foo"] matches foo and &["", "foo", "bar"] matches ::foo::bar.

Such rules are used to expand attributes within an impl_scope!.

Required Methods

fn path(&self) -> SimplePath

Attribute path

Rules are matched via a path, e.g. &["foo"] matches foo and &["", "foo", "bar"] matches ::foo::bar.

Note that we cannot use standard path resolution, so we match only a single path, as defined.

fn apply(&self, attr: Attribute, scope: &mut Scope) -> Result<()>

Function type of ScopeAttr rule

Input arguments:

• attr: the invoking attribute. It is suggested to parse arguments using Attribute::parse_args or Attribute::parse_args_with.
• scope: mutable reference to the implementation scope. Usually an attribute rule function will read data from the scope and append its output to Scope::generated.

Provided Methods

fn support_repetition(&self) -> bool

Whether repeated application is valid

If this is false (the default), then an error will be omitted on repeated usage of the attribute. This mostly serves to emit better error messages in cases where the first application modifies the input.

Implementors

impl ScopeAttr for AttrImplDefault