Struct Env 

pub struct Env { /* private fields */ }

Current context of environment variable parsing.

Env keeps track of nesting by storing the name of the “current” variable. A type’s parser may choose to read the value of the current variable using value, or use it to parse its fields using nest and field.

Implementations

impl Env

pub fn value(&self) -> Result<OsString, Error>

Read the value of the current variable.

Errors

Returns Error::Missing if the current variable is missing.

Examples

enum Color {
    Orange,
    Blue,
}

impl Tenvy for Color {
   fn from_env(env: &Env) -> Result<Self, Error> {
      #[derive(Debug, thiserror::Error)]
      #[error("expected `orange` or `blue`")]
      struct InvalidColor;

      match env.value()?.to_str() {
          Some("orange") => Ok(Self::Orange),
          Some("blue") => Ok(Self::Blue),
          _ => Err(Error::invalid_value(env, InvalidColor)),
      }
   }
}

pub fn nest<K: AsRef<OsStr>>(&self, field: K) -> Self

Construct a new context for a field, i.e. append field to the current variable name. The separator _ is added automatically.

pub fn field<K: AsRef<OsStr>, T: Tenvy>(&self, field: K) -> Result<T, Error>

Parse a value in a nested context.

Examples

impl Tenvy for Database {
    fn from_env(env: &Env) -> Result<Self, Error> {
        Ok(Self {
            url: env.field("URL")?,
        })
    }
}

Trait Implementations

impl Debug for Env

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.