Struct EnvList 

pub struct EnvList { /* private fields */ }

A fixed list of environment variables.

Use this for an environment that does not come from this process, such as the variables an SSH client forwards or a set read from a configuration file, and for tests that need deterministic lookups.

Variables are stored as an ordered list of (key, value) pairs, matching how an environment is passed around at the process boundary. Duplicate keys are allowed, and lookups return the last matching value.

Implementations

impl EnvList

pub fn new() -> Self

Build an empty environment.

Returns

An EnvList with no variables.

Errors and panics

This method does not fail or intentionally panic.

pub fn from_process() -> Self

Capture the current process environment.

The result is a snapshot: later changes to the process environment are not visible to it. Use ProcessEnv to read through to the live environment instead.

Returns

An EnvList containing all variables yielded by std::env::vars at the time of the call.

Errors and panics

This method does not return errors. It has the same panic behavior as std::env::vars if the process environment contains invalid data.

pub fn from_pairs<I, K, V>(iter: I) -> Self

where I: IntoIterator<Item = (K, V)>, K: Into<String>, V: Into<String>,

Build an environment from (key, value) pairs.

Pair order and duplicate keys are preserved. Later duplicates shadow earlier values for get and has.

Parameters

• iter — variables to store.

Returns

An EnvList containing the supplied variables.

Errors and panics

This method does not return errors. It may panic only if allocation for the stored strings fails.

pub fn set( &mut self, key: impl Into<String>, value: impl Into<String>, ) -> &mut Self

Append a variable to the list.

If key is already present, the new value shadows earlier values for get and has.

Parameters

• key — variable name.
• value — variable value.

Returns

self, for chaining.

Errors and panics

This method does not return errors. It may panic only if allocation for the stored strings fails.

Trait Implementations

impl Clone for EnvList

fn clone(&self) -> EnvList

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for EnvList

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

Formats the value using the given formatter.

impl Default for EnvList

fn default() -> EnvList

Returns the “default value” for a type.

impl Env for EnvList

fn get(&self, key: &str) -> Option<String>

Return a variable’s value.

fn has(&self, key: &str) -> bool

Return whether a variable is present with a non-empty value.