Specifications¶

The Specification pattern is a composable predicate over candidate objects.

Core contract¶

Specification — Abstract base with is_satisfied_by(candidate) → bool
ComposableSpecification — Adds &, |, ~ for fluent logical composition
ExpressionSpecification — Wraps a user-provided callable predicate

Logical operators¶

AndSpecification — Satisfied when both specs are satisfied (a & b)
OrSpecification — Satisfied when at least one spec is satisfied (a | b)
NotSpecification — Satisfied when the wrapped spec is not satisfied (~a)

Composed results remain composable. (a & b) | c chains naturally.

When to use¶

Specifications are ideal for querying, validation, and filtering. Define a predicate once, then compose it with others rather than writing nested if-statements.