Trait attribute_derive::ConvertParsed

source ·

pub trait ConvertParsedwhere
    Self: Sized,
    Self::Type: Error,{
    type Type;

    // Required method
    fn convert(value: Self::Type) -> Result<Self>;

    // Provided methods
    fn default_by_default() -> bool { ... }
    fn default() -> Self { ... }
    fn as_flag() -> Option<Self::Type> { ... }
    fn aggregate(
        this: Option<IdentValue<Self::Type>>,
        other: Option<IdentValue<Self::Type>>,
        error_msg: &str
    ) -> Result<Option<IdentValue<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.

Required Associated Types§

source

type Type

The type this can be converted from

Required Methods§

source

fn convert(value: Self::Type) -> Result<Self>

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§

source

fn default_by_default() -> bool

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, Vec and bool currently)

source

fn default() -> Self

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

This is necessary as the Default trait cannot be used in expanded code, but normally you can easily implement it using it:

impl ConvertParsed for bool {
    fn default() -> Self {
        Default::default()
    }
}

source

fn as_flag() -> Option<Self::Type>

Returns the value when this type is specified as flag i.e. just #[attr(default)] instead of #[attr(default=true)]. This relies on Self::default.

source

fn aggregate( this: Option<IdentValue<Self::Type>>, other: Option<IdentValue<Self::Type>>, error_msg: &str ) -> Result<Option<IdentValue<Self::Type>>>

Should values of this type be aggregated instead of conflict if specified multiple times

Currently this is only implemented for Arrays

Trait attribute_derive::ConvertParsed

Required Associated Types§

type Type

Required Methods§

fn convert(value: Self::Type) -> Result<Self>

Provided Methods§

fn default_by_default() -> bool

fn default() -> Self

fn as_flag() -> Option<Self::Type>

fn aggregate( this: Option<IdentValue<Self::Type>>, other: Option<IdentValue<Self::Type>>, error_msg: &str ) -> Result<Option<IdentValue<Self::Type>>>

Implementations on Foreign Types§

impl ConvertParsed for Mut

type Type = Mut

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for RArrow

type Type = RArrow

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Question

type Type = Question

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Loop

type Type = Loop

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for CaretEq

type Type = CaretEq

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Semi

type Type = Semi

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for TypeParamBound

type Type = TypeParamBound

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for DeriveInput

type Type = DeriveInput

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for f64

type Type = LitFloat

fn convert(value: LitFloat) -> Result<f64>

impl ConvertParsed for Meta

type Type = Meta

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Pound

type Type = Pound

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for TypeReference

type Type = TypeReference

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Impl

type Type = Impl

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Virtual

type Type = Virtual

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for ExprMacro

type Type = ExprMacro

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Async

type Type = Async

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for MinusEq

type Type = MinusEq

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Enum

type Type = Enum

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for ExprBlock

type Type = ExprBlock

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Match

type Type = Match

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Index

type Type = Index

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for ExprTuple

type Type = ExprTuple

fn convert(s: Self) -> Result<Self>

impl ConvertParsed for Ge

type Type = Ge

fn convert(s: Self) -> Result<Self>