Enum Scope 

pub enum Scope {
    None,
    User(String),
    Tenant(String),
}

The subject of a flag check.

Three kinds, because three are what applications actually roll out to:

• a user, by whatever identifier they log in with;
• a tenant, when a feature is bought or enabled per customer rather than per person;
• nobody in particular (Scope::none), for a switch that is on or off for the whole installation.

The identifier is a String and not a generic parameter on purpose. A flag store has to write it down, an operator has to type it into a console, and a percentage rollout has to hash it — all three want text, and a type parameter here would spread through every signature in the crate to buy nothing.

use rustlavel_flags::Scope;

assert_eq!(Scope::user("ada").id(), "ada");
assert_eq!(Scope::user_id(41).id(), "41");
assert_eq!(Scope::tenant("acme").key(), "tenant:acme");
assert_eq!(Scope::none().id(), "");

Variants

None

Everybody. Built with Scope::none.

User(String)

One logged-in user, by their authentication identifier.

Tenant(String)

One tenant, team, organisation — whatever the application calls it.

Implementations

impl Scope

pub fn none() -> Self

The global scope: a flag that is simply on or off, for everyone.

Named none rather than global because of how it reads at the call site — flags.active("maintenance", &Scope::none()) says “there is nobody in particular here”, which is the fact the caller has.

pub fn user(id: impl Into<String>) -> Self

One user, by the identifier they log in with.

pub fn user_id(id: i64) -> Self

One user, by a numeric primary key — the common case in an application whose users table is keyed by bigint.

pub fn tenant(name: impl Into<String>) -> Self

One tenant, by name or by id.

pub fn id(&self) -> &str

The identifier, or "" for Scope::none.

The empty string is deliberate: a resolver that does not care which kind of scope it was given can read scope.id() unconditionally, and a global check falls through whatever test it applies rather than panicking or matching some sentinel value.

pub fn id_as<T: FromStr>(&self) -> Option<T>

The identifier parsed into a type: scope.id_as::<i64>().

None when the scope is global, or when the identifier is not that type — a resolver keyed on a numeric user id gets one answer for both, which is right, because it cannot serve either.

pub fn kind(&self) -> &'static str

"global", "user" or "tenant" — for logs and for the store key.

pub fn is_none(&self) -> bool

Whether this is the global scope.

pub fn key(&self) -> String

The string a FlagStore writes an override under.

The kind is part of the key, so a user called acme and a tenant called acme are two different subjects and cannot inherit each other’s overrides. An identifier containing a colon is left alone rather than escaped — the prefix already separates the namespaces, and the only way two keys can still collide is if one subject’s identifier is literally another kind’s prefix plus another subject’s identifier, which is a collision between two identifiers the application itself issued.

Trait Implementations

impl Clone for Scope

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Scope

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

Formats the value using the given formatter.

impl Default for Scope

fn default() -> Self

Returns the “default value” for a type.

impl Display for Scope

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

Formats the value using the given formatter.

impl Eq for Scope

impl Hash for Scope

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 Scope

fn cmp(&self, other: &Self) -> 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,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for Scope

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for Scope

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

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

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

Tests less than (for self and other) and is used by the < operator.

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

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

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

Tests greater than (for self and other) and is used by the > operator.

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

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

impl StructuralPartialEq for Scope