Trait FromArg 

pub trait FromArg: Sized {
    // Required method
    fn from_arg(arg: &Arg) -> Result<Self>;
}

Converts a single Arg into a typed value.

Implement this trait to support a type as a field in #[derive(Attribute)] structs. Built-in impls cover bool, String, integer/float primitives, char, Ident, Path, Expr, LitStr, LitInt, Option<T>, Vec<T>, and Args.

Required Methods

fn from_arg(arg: &Arg) -> Result<Self>

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl FromArg for Expr

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for bool

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for char

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for f32

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for f64

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for i8

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for i16

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for i32

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for i64

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for i128

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for u8

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for u16

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for u32

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for u64

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for u128

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for String

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for Ident

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for LitInt

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for LitStr

fn from_arg(arg: &Arg) -> Result<Self>

impl FromArg for Path

fn from_arg(arg: &Arg) -> Result<Self>

impl<T: FromArg> FromArg for Option<T>

fn from_arg(arg: &Arg) -> Result<Self>

impl<T: FromArg> FromArg for Vec<T>

fn from_arg(arg: &Arg) -> Result<Self>

Implementors

impl FromArg for Args