Validated<T extends Object?>.check constructor

Validated<T extends Object?>.check(T value, bool predicate(T value), { required String error, })

Validates a value against a predicate and returns the result.

This is the primary factory method for starting validation chains. Evaluates predicate on value and returns either a Validated.valid or Validated.invalid result. For chaining additional validations, use the ValidatedOps.check extension method on the returned result.

Parameters:

• value: The value to validate
• predicate: Function that returns true if valid, false if invalid
• error: Error message to include if validation fails

Example:

// Single validation
final result = Validated.check(
  userInput,
  (input) => input.isNotEmpty,
  error: 'Name cannot be empty',
);

// Chaining multiple validations
final validation = Validated.check(
  email,
  (e) => e.isNotEmpty,
  error: 'Required',
)
  .check((e) => e.contains('@'), error: 'Must contain @')
  .check((e) => !e.endsWith('.'), error: 'Cannot end with period');

Implementation

factory Validated.check(
  T value,
  bool Function(T value) predicate, {
  required String error,
}) => predicate(value) ? Valid._(value) : Invalid._({error});