spinoso_env

Struct System

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pub struct System { /* private fields */ }
Expand description

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§

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impl System

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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();
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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.

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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.

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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§

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impl Clone for System

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fn clone(&self) -> System

Returns a copy of the value. Read more
1.0.0 · source§

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

Performs copy-assignment from source. Read more
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impl Debug for System

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

Formats the value using the given formatter. Read more
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impl Default for System

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fn default() -> System

Returns the “default value” for a type. Read more
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impl Hash for System

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

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl Ord for System

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

This method returns an Ordering between self and other. Read more
1.21.0 · source§

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

Compares and returns the maximum of two values. Read more
1.21.0 · source§

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

Compares and returns the minimum of two values. Read more
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fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized,

Restrict a value to a certain interval. Read more
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impl PartialEq for System

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

Tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl PartialOrd for System

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

This method returns an ordering between self and other values if one exists. Read more
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fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator. Read more
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fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator. Read more
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fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator. Read more
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fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl Copy for System

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impl Eq for System

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impl StructuralPartialEq for System

Auto Trait Implementations§

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impl Freeze for System

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impl RefUnwindSafe for System

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impl Send for System

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impl Sync for System

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impl Unpin for System

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impl UnwindSafe for System

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.