Trait attribute_derive::ConvertParsed

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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§

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type Type

The type this can be converted from

Required Methods§

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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§

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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)

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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()
    }
}

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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.

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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 Enum

type Type = Enum

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

impl ConvertParsed for Async

type Type = Async

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

impl ConvertParsed for ExprContinue

type Type = ExprContinue

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

impl ConvertParsed for ExprBlock

type Type = ExprBlock

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

impl ConvertParsed for f32

type Type = LitFloat

fn convert(value: LitFloat) -> Result<f32>

impl ConvertParsed for GenericParam

type Type = GenericParam

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

impl ConvertParsed for ExprPath

type Type = ExprPath

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

impl ConvertParsed for Await

type Type = Await

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

impl ConvertParsed for LitFloat

type Type = LitFloat

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

impl ConvertParsed for Priv

type Type = Priv

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

impl ConvertParsed for ImplItemMethod

type Type = ImplItemMethod

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

impl ConvertParsed for ExprBinary

type Type = ExprBinary

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

impl ConvertParsed for Receiver

type Type = Receiver

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

impl ConvertParsed for Member

type Type = Member

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

impl ConvertParsed for Mut

type Type = Mut

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

impl ConvertParsed for usize

type Type = LitInt

fn convert(value: LitInt) -> Result<usize>

impl ConvertParsed for Dyn

type Type = Dyn

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

impl ConvertParsed for TypeReference

type Type = TypeReference

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

impl ConvertParsed for File

type Type = File

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

impl ConvertParsed for ItemMacro2

type Type = ItemMacro2

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

impl ConvertParsed for ItemUse

type Type = ItemUse

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

impl ConvertParsed for Star

type Type = Star

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

impl ConvertParsed for BareFnArg

type Type = BareFnArg

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