@reagent -- That's a really good post, though I think the module is a bit overkill for this.  I wasn't aware you could use threequals with regular expressions, so I tried the following in the `main_app_url_helper?` method:

```ruby
/\A\w+(_path|_url)\z/ === method.to_s
```

I feel like it's a bit less clear than the `end_with?`, but maybe that doesn't matter since the method name of `main_app_url_helper?` will hopefully help.  Any thoughts on that?

@efatsi -- Are you concerned that the `main_app` would respond to a method such as `foobar`?  If so, I can keep the `main_app_url_helper?` method and reference in both the `method_missing` and `respond_to_missing?` methods.