Trait FromEnvVar

pub trait FromEnvVar:
    Debug
    + Sized
    + 'static {
    type Error: Error;

    // Required method
    fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>;
}

Trait for loading primitives from the environment. These are simple types that should correspond to a single environment variable. It has been implemented for common integer types, String, url::Url, tracing::Level, and std::time::Duration.

It aims to make FromEnv implementations easier to write, by providing a default implementation for common types.

Required Associated Types

type Error: Error

Error type produced when parsing the primitive.

Required Methods

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

Load the primitive from the environment at the given variable.

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 FromEnvVar for bool

type Error = ParseBoolError

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for i8

type Error = <i8 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for i16

type Error = <i16 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for i32

type Error = <i32 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for i64

type Error = <i64 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for i128

type Error = <i128 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for isize

type Error = <isize as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for u8

type Error = <u8 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for u16

type Error = <u16 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for u32

type Error = <u32 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for u64

type Error = <u64 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for u128

type Error = <u128 as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for usize

type Error = <usize as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for String

type Error = Infallible

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for Duration

type Error = ParseIntError

fn from_env_var(s: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for Address

type Error = <Address as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for Bytes

type Error = <Bytes as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for Level

type Error = <Level as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for Url

type Error = <Url as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl FromEnvVar for U256

type Error = <Uint<256, 4> as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl<T> FromEnvVar for Option<T>

where T: FromEnvVar,

type Error = <T as FromEnvVar>::Error

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

impl<const N: usize> FromEnvVar for FixedBytes<N>

Available on crate feature alloy only.

type Error = <FixedBytes<N> as FromStr>::Err

fn from_env_var(env_var: &str) -> Result<Self, FromEnvErr<Self::Error>>

Implementors