Struct Context

pub struct Context<State> {
    pub action: ActionContext<State>,
    pub state: Option<State>,
}

The context of the action. This is handed into actions when they’re invoked, and is the underpinning mechanism for distributing side-effects, as well as action composition.

At compile time, the action context grants us, and the consumers, the ability to structure action systems in typesafe ways. At runtime, the context is used to distribute the state of the system, as well as any additional crate-specific plumbing that the action may require.

Fields

action: ActionContext<State>

The action context, describing any additional context that the action may carry.

state: Option<State>

The state of the system, determined by the consumer. This can be absent if the various actions are called before being properly initialized. The type system should prevent this most of the time by requiring the state to be present before invoking actions or calling them as services.

Implementations

impl<State> Context<State>

pub fn from_action(action: ActionContext<State>) -> Self

Create a new context with the given action.

pub fn from_state(state: State) -> Self

Create a new context with the given state.

pub fn state(&self) -> Result<State, StateNotReadyError>

where State: Clone,

Return the state. Returns an error if the state is not ready.

pub fn with_action(action: ActionContext<State>, state: State) -> Self

Create a new context with the given state and action context.

Trait Implementations

impl<State: Clone> Clone for Context<State>

fn clone(&self) -> Context<State>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<State: Debug> Debug for Context<State>

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

Formats the value using the given formatter.

impl<State: Default> Default for Context<State>

fn default() -> Context<State>

Returns the “default value” for a type.

impl<State> From<ActionContext<State>> for Context<State>

fn from(action: ActionContext<State>) -> Self

Converts to this type from the input type.

impl<State> From<State> for Context<State>

fn from(state: State) -> Self

Converts to this type from the input type.