Where is my :nodoc:?

Rubydoc.info uses YARD for all of its documentation generation. Although YARD is mostly compatible with RDoc, it does not support RDoc "directives" such as :stopdoc: or :nodoc:. There are a few reasons for this, but the most important is that it is very easy to misuse :nodoc:, and this misuse often causes your readers to miss out on vital information in your documentation.

The @private Tag

Fortunately, YARD has a few alternatives to :nodoc: that allow you to benefit from powerful documentation while trimming down on certain unwanted details. YARD has a meta-data based "tag style" formatting, and has a @private tag that can be applied to any documentable element. This marks the element as having "private" visibility, and is meant to be used when the element cannot be marked as private (because it is a class/module/constant or other non-method object).

How to Use @private

Note that this tag alone does not hide the object from your documentation. You need to also specify --no-private (not --private) in your .yardopts file (see how to setup a .yardopts file here). This is done to ensure that @private is not used as a "drop-in" replacement for :nodoc:. The extra step is intentional, and we want you to take this time to reflect on why you are hiding information from your documentation.

When to Use @private

The @private tag is simply meant to fill the visibility gap that is currently missing from Ruby for constants.
It is not recommended practice to overuse @private, and is generally never acceptable for use with methods (since they can be marked as private quite easily). In general, you should only use this tag to hide internal classes that can never be used externally. However, carefully note the connotation of the term "private" versus "nodoc". We still want you to think about documenting these objects, since they might be valuable to an internals API! By marking an object as private, you should not be saying "I will not document this", you should be saying that the documentation for the object is not meant for public consumption.

Also note that Ruby 1.9.3 will introduce the concept of private constants, and @private might eventually disappear completely.