Increment and Decrement with :initial => nil doesn't return nil on missing key.

[lawrencepit]

This is somewhat related to issue #68.

When calling increment or decrement with the option :initial => nil, then on a missing key it will not return nil, but the increment amount.

[mperham]

Sorry, I guess I never saw this issue. What's the use case for this functionality? Why would you want to create a nil counter?

[lawrencepit]

1. I think it should be consistent with the Rails.cache API (to aid with tests as well) :

#68 (comment)

2. The use case: we want to prevent doing this:

Rails.cache.increment(cache_key, 1, :initial => very_resource_intensive_and_dynamic_operation)

instead we want to do:

next = Rails.cache.increment(cache_key, 1, :initial => nil)
unless next
  initial = very_resource_intensive_and_dynamic_operation
  next = Rails.cache.increment(cache_key, 1, :initial => initial)
end

so the resource intensive operation is performed only once during the lifetime of the service.

[mperham]

Fair enough. Can you send a pull request please and be sure to update History.md with a line to give yourself credit.

[lawrencepit]

See #189