Struct StartPrecondition 

pub struct StartPrecondition {
    pub workflow: WorkflowKey,
    pub phases: Vec<Value>,
    pub reason: LocalizedText,
}

What must already be true of another case before this workflow may be started.

Why a declaration

A projector is pure and cannot read another case, and the executor is the wrong place for a domain rule about when a case may exist: «a traveler is registered only while a trip is open» belongs to neither. The workflow declares what it needs; the runtime, which has the other cases in hand already, decides whether it is there.

What it costs when it is not met

The start act is not offered at all, so it cannot be proposed and cannot be refused later. The reason travels in the catalogue instead, which is the honest limit of this shape: with no act there is no refusal to attach a notice to, so whether the user hears why depends on the sentence the writing stage produces. A deployment that needs the reason guaranteed should keep an operation that refuses it rather than one that is absent.

Fields

workflow: WorkflowKey

The workflow the required case belongs to.

phases: Vec<Value>

The phases that satisfy it, as that workflow’s phase serializes.

reason: LocalizedText

Why, in words a user can read, when it is not met.

Implementations

impl StartPrecondition

pub fn new( workflow: impl Into<WorkflowKey>, phases: impl IntoIterator<Item = Value>, reason: LocalizedText, ) -> Self

Requires a case of workflow to be in one of phases, already serialized.

The infallible primitive. Prefer Self::requires, which takes the other workflow’s own phase type so the compiler checks the spelling.

pub fn requires<P: Serialize>( workflow: impl Into<WorkflowKey>, phases: &[P], reason: LocalizedText, ) -> Result<Self, HashError>

Requires a case of workflow to be in one of phases.

The phases are serialized here, so an adopter names them with the other workflow’s own type and the compiler checks the spelling.

Errors

HashError when a phase does not serialize, which is the workflow’s own type failing to round-trip.

pub fn satisfied_by(&self, view: &ErasedWorkflowView) -> bool

Whether view is a case that satisfies this precondition.

Trait Implementations

impl Clone for StartPrecondition

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 StartPrecondition

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for StartPrecondition

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for StartPrecondition

impl PartialEq for StartPrecondition

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for StartPrecondition

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for StartPrecondition