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 Dollar

type Type = Dollar

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

impl ConvertParsed for Group

type Type = Group

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

impl ConvertParsed for ExprWhile

type Type = ExprWhile

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

impl ConvertParsed for In

type Type = In

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

impl ConvertParsed for Slash

type Type = Slash

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

impl ConvertParsed for LitByteStr

type Type = LitByteStr

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

impl ConvertParsed for Gt

type Type = Gt

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

impl ConvertParsed for u64

type Type = LitInt

fn convert(value: LitInt) -> Result<u64>

impl ConvertParsed for Question

type Type = Question

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

impl ConvertParsed for TypeGroup

type Type = TypeGroup

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

impl ConvertParsed for u32

type Type = LitInt

fn convert(value: LitInt) -> Result<u32>

impl ConvertParsed for ExprLoop

type Type = ExprLoop

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

impl ConvertParsed for Typeof

type Type = Typeof

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

impl ConvertParsed for Member

type Type = Member

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

impl ConvertParsed for Priv

type Type = Priv

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

impl ConvertParsed for char

type Type = LitChar

fn convert(value: LitChar) -> Result<char>

impl ConvertParsed for UnOp

type Type = UnOp

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

impl ConvertParsed for Lit

type Type = Lit

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

impl ConvertParsed for ShrEq

type Type = ShrEq

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

impl ConvertParsed for And

type Type = And

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

impl ConvertParsed for Where

type Type = Where

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

impl ConvertParsed for PercentEq

type Type = PercentEq

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

impl ConvertParsed for BareFnArg

type Type = BareFnArg

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