Trait attribute_derive::ConvertParsed

source · [−]
pub trait ConvertParsed where
    Self: Sized,
    Self::Type: Error, {
    type Type;
    fn convert(value: Self::Type) -> Result<Self>;

    fn default_by_default() -> bool { ... }

    fn default() -> Self { ... }

    fn as_flag() -> Option<Self::Type> { ... }
}
Expand description

Helper trait to convert syn types implementing Parse like LitStr to rust types like String

You probably don’t need to implement this trait, as most syn types like LitStr and Type or that have a direct equivalent in those like String, char or f32 are already implemented. A special treatment have Vecs which are parsed using the helper Array with the syntax [a, b, c] and Options that will be None if not specified and Some when the value is specified via the attribute. It is not specified via Some(value) but as just value.

Associated Types

The type this can be converted from

Required methods

This takes Self::Type and converts it to Self.

This can return an error, e.g. when parsing an integer too large for a u8 into an u8

Provided methods

Should values of this type return their default when they are not specified even when the default flag is not specified (only returns true for Option currently)

The default value, this is necessary to implement the implicit default behavior of Option

Should values of this type be able to be defined as flag i.e. just #[attr(default)] instead of #[attr(default=true)]

Implementations on Foreign Types

Implementors