Provide fail-fast bang equivalents for each API call

[thbar]

A first pull-request after our discussion at #4.

Not completely happy with the current code, but it works though! Feel free to change whatever suits you.

I can blindly call add_emails! and I will get an exception if the list does not exist, or delete_list! will raise an error if the list does not exist as well.

[JEG2]

I would like to get away from manually specifying all of the bang method variants. Could we read the public method list and wrap all of those or some similar trick?

[thbar]

I thought about that but wanted to have your opinion on the first stab already!

I can have a look at that, maybe with some filtering.

[thbar]

Here's an updated version with less manual work. I added a test to verify the behaviour too.

[JEG2]

Closer to what I had in mind yeah, but can we use an extended() (or included()) hook to avoid the need for bang_method() altogether. Or alternately, we could just define a method_missing() that forwards to the non-bang methods. Thoughts?

[thbar]

Well at this point, I would either leave it that way, or use extended/included, or method_missing, it's fairly equivalent to me given the size of the gem.

Let me know what you prefer and I'll do that!

I'll also add some specs around the verify! behaviour.

[thbar]

Hey @JEG2, any input on that? Let me know and I'll finish it!

[JEG2]

Sorry. I have been busy.

The thing I don't like about the current version is that you purposefully had to move the call to bang_method() to after all the methods definitions. I would rather not need to worry that we keep it in right place as we go forward.

For that reason, I think I would prefer:

1. Define method_missing()
2. When called, check to see if it's a bang variant of what we already support
3. If so, forward with error tossing
4. If not, delegate to super
5. Also override respond_to_missing() (http://robots.thoughtbot.com/post/28335346416/always-define-respond-to-missing-when-overriding)

This seems more maintenance friendly.

Thoughts?

[thbar]

Sure, no worry on the delay really! It's just that I may have a bit of spare time this week-end so I wanted to see if I could have your input before.

All that seems more maintenance friendly, absolutely; I'll update my branch with that.

Thanks!