cached method
Wraps this validator with single-value caching.
Returns the cached result if the input value hasn't changed, avoiding redundant validation computations.
final cached = emailRule.cached();
cached.validate('test@example.com'); // Computed
cached.validate('test@example.com'); // Cached!
cached.validate('other@example.com'); // Computed
This is ideal for form fields that validate on every keystroke.
Note: Returns a CachedFormix instance with mutable state.
Implementation
CachedFormix<T, E> cached() => CachedFormix(this);