Struct Requirement 

pub struct Requirement { /* private fields */ }

A single boolean check over some set of cells, attached to a cell.

Its predicate must be a pure, deterministic function of its input values and immutable captured constants, with no externally observable side effects. Equal inputs produce equivalent results or errors. There is no guarantee that the predicate executes, or when or how often it executes.

Implementations

impl Requirement

pub fn new<F>(inputs: Vec<CellId>, input_types: Vec<TypeId>, f: F) -> Self

where F: Fn(&[&dyn Any]) -> Result<bool, Error> + 'static,

Creates a requirement from explicit TypeIds and a type-erased predicate.

• Precondition: inputs.len() == input_types.len().
• Precondition: f satisfies Requirement’s purity contract.

pub fn from_fn_1<A, F>(input: CellId, f: F) -> Self

where A: Any + 'static, F: Fn(&A) -> Result<bool, Error> + 'static,

Creates a 1-input requirement from a typed closure.

The TypeId for A is captured automatically. The requirement is validated against its cell registration when passed to crate::sheet::Sheet::add_requirement.

• Precondition: f satisfies Requirement’s purity contract.

pub fn from_fn_2<A, B, F>(inputs: [CellId; 2], f: F) -> Self

where A: Any + 'static, B: Any + 'static, F: Fn(&A, &B) -> Result<bool, Error> + 'static,

Creates a 2-input requirement from a typed closure.

inputs[0] maps to A and inputs[1] maps to B. TypeIds are captured automatically. The requirement is validated when passed to crate::sheet::Sheet::add_requirement.

• Precondition: f satisfies Requirement’s purity contract.