framework/validators/Validator.php
public static function createValidator($type, $model, $attributes, $params = [])
    {
        $params['attributes'] = $attributes;

        if ($type instanceof \Closure || ($model->hasMethod($type) && !isset(static::$builtInValidators[$type]))) {
            // method-based validator
            $params['class'] = __NAMESPACE__ . '\InlineValidator';
            $params['method'] = $type;
        } else {
            if (isset(static::$builtInValidators[$type])) {
                $type = static::$builtInValidators[$type];
            }
            if (is_array($type)) {
                $params = array_merge($type, $params);
            } else {
                $params['class'] = $type;
            }
        }

        return Yii::createObject($params);
    }
public static function createValidator($type, $model, $attributes, $params = [])
    {
        $params['attributes'] = $attributes;

        if ($type instanceof \Closure || ($model->hasMethod($type) && !isset(static::$builtInValidators[$type]))) {
            // method-based validator
            $params['class'] = __NAMESPACE__ . '\InlineValidator';
            $params['method'] = $type;
        } else {
            if (isset(static::$builtInValidators[$type])) {
                $type = static::$builtInValidators[$type];
            }
            if (is_array($type)) {
                $params = array_merge($type, $params);
            } else {
                $params['class'] = $type;
            }
        }

        return Yii::createObject($params);
    }
Creates a validator object.
@param string|\Closure $type the validator type. This can be either:
* a built-in validator name listed in [[builtInValidators]];
* a method name of the model class;
* an anonymous function;
* a validator class name.
@param \yii\base\Model $model the data model to be validated.
@param array|string $attributes list of attributes to be validated. This can be either an array of
the attribute names or a string of comma-separated attribute names.
@param array $params initial values to be applied to the validator properties.
@return Validator the validator