Enum Demand 

pub enum Demand {
    Never,
    Expr,
    Value,
    Bool,
    Class(ClassId),
    Shape(ShapeId),
}

How strongly an argument position demands its value be forced.

A Demand is the contract an EvalPolicy consults when preparing call arguments: it states how far a value must be driven before the callable sees it, from “leave it as an unevaluated expression” to “force it to a value of a specific class or shape”. The kernel only defines the demand vocabulary; libraries decide how to satisfy each variant.

Examples

use sim_kernel::eval::Demand;

// The vocabulary is plain, copyable data.
let demand = Demand::Value;
assert_eq!(demand, Demand::Value);
assert_ne!(Demand::Value, Demand::Expr);

Variants

Never

Never force; the argument is passed through untouched.

Expr

Force to an expression form (leave it quoted, do not evaluate).

Value

Force to a fully evaluated value.

Bool

Force to a value and coerce to its boolean truth.

Class(ClassId)

Force to a value required to be of the given class.

Shape(ShapeId)

Force to a value required to match the given shape.

Trait Implementations

impl Clone for Demand

fn clone(&self) -> Demand

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Demand

impl Debug for Demand

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

Formats the value using the given formatter.

impl Eq for Demand

impl PartialEq for Demand

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

Tests for self and other values to be equal, and is used by ==.

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

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

impl StructuralPartialEq for Demand