Struct spinoso_env::System

pub struct System { /* private fields */ }

A hash-like accessor for environment variables using platform APIs.

System is an accessor to the host system’s environment variables using the functions provided by the Rust Standard Library in the std::env module.

Use of this ENV backend allows Ruby code to access and modify the host system. It is not appropriate to use this backend in embedded or untrusted contexts.

Examples

Fetching an environment variable:

const ENV: System = System::new();
assert!(ENV.get(b"PATH")?.is_some());

Setting an environment variable:

const ENV: System = System::new();
ENV.put(b"ENV_BACKEND", Some(b"spinoso_env::System"))?;
assert_eq!(
    std::env::var("ENV_BACKEND").as_deref(),
    Ok("spinoso_env::System")
);

Implementations

impl System

pub const fn new() -> Self

Constructs a new, default ENV System backend.

The resulting environment variable accessor has access to the host system via platform APIs.

Examples

const ENV: System = System::new();

pub fn get( self, name: &[u8] ) -> Result<Option<Cow<'static, [u8]>>, ArgumentError>

Retrieves the value for environment variable name.

Returns None if the named variable does not exist. If the retrieved environment variable value cannot be converted from a platform string to a byte vector, None is returned.

Implementation notes

This method accesses the host system’s environment using env::var_os.

Examples

const ENV: System = System::new();
assert!(ENV.get(b"PATH")?.is_some());

Errors

If name contains a NUL byte, e.g. b'\0', an error is returned.

If the environment variable name or value cannot be converted from a byte vector to a platform string, an error is returned.

pub fn put(self, name: &[u8], value: Option<&[u8]>) -> Result<(), Error>

Sets the environment variable name to value.

If the value given is None the environment variable is deleted.

Implementation notes

This method accesses the host system’s environment using env::set_var and env::remove_var.

Examples

const ENV: System = System::new();
ENV.put(b"RUBY", Some(b"Artichoke"))?;
assert_eq!(ENV.get(b"RUBY")?.as_deref(), Some(&b"Artichoke"[..]));
ENV.put(b"RUBY", None)?;
assert_eq!(ENV.get(b"RUBY")?, None);

Errors

If name contains a NUL byte, e.g. b'\0', an argument error is returned.

If name contains an ‘=’ byte, e.g. b'=', an EINVAL error is returned.

If value is Some and contains a NUL byte, e.g. b'\0', an argument error is returned.

If the environment variable name or value cannot be converted from a byte vector to a platform string, an error is returned.

pub fn to_map(self) -> Result<HashMap<Vec<u8>, Vec<u8>>, ArgumentError>

Serialize the environ to a HashMap.

Map keys are environment variable names and map values are environment variable values.

Implementation notes

This method accesses the host system’s environment using env::vars_os.

Examples

const ENV: System = System::new();
let map = ENV.to_map()?;
assert!(map.contains_key(&b"PATH"[..]));

Errors

If any environment variable name or value cannot be converted from a platform string to a byte vector, an error is returned.

Trait Implementations

impl Clone for System

fn clone(&self) -> System

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for System

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

Formats the value using the given formatter.

impl Default for System

fn default() -> System

Returns the “default value” for a type.

impl Hash for System

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for System

fn cmp(&self, other: &System) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl PartialEq for System

fn eq(&self, other: &System) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for System

fn partial_cmp(&self, other: &System) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for System

impl Eq for System

impl StructuralPartialEq for System