I'm not sure I quite get the scenario, but you might want to look at conditional rules: http://laravel.com/docs/validation#conditionally-adding-rules

I think you need to make it required (if the other option is set), otherwise the field is optional

Thanks elite123, I hadn't seen the 'sometimes' attribute before. I don't think it quite works for what I'm doing though (maybe I'm just not connecting the dots?).

As an example, I have a validator that requires a field only if a certain value is in an array (from HTML checkboxes). The problem is that just using Validate::extend(), it doesn't require this check. In other words, it only runs the validation against the value if it's present, it doesn't fail if it isn't. In order to require the check, I had to call on the Validator->addImplicitExtension() method. This works but I feel like it breaks the separation of logic because now I have validation declarations (acting on an instance of the Validation class) inside my CustomValidator class. Smells bad. :)

Am I missing something? Is there another way to do this?

What if instead closure I want to extend the Validator class itself like shown in laravel 4.2 docs. How can I create implicit method extension ?

<?php

class CustomValidator extends Illuminate\Validation\Validator {

    public function validateFoo($attribute, $value, $parameters)
    {
        return $value == 'foo';
    }

}

@filipzelic

A bit late, i know (also my first post here). This is what you can do:

<?php

class CustomValidator extends Illuminate\Validation\Validator {
    
    public function __construct( $translator, $data, $rules, $messages = array(), $customAttributes = array() )
    {
        parent::__construct( $translator, $data, $rules, $messages, $customAttributes );
        $this->implicitRules[] = Str::studly('foo_bar');
    }    

    public function validateFooBar($attribute, $value, $parameters)
    {
        return $value == 'foo' || $value == 'bar';
    }

}

Just add the rule to the $implicitRules array.