Sometimes opts passed in might respond to ==, e.g. `Arel::Nodes::Grouping`. In this case, `opts == :chain` returns `Arel::Nodes::Equality` which causes odd behaviour. Prefer `if :chain == opts` which guarantees that `Symbol#==` would be invoked. Alternatively consider `eql?`.
Since the strings are dynamically computed from a constant, the actual strings we're creating are a known set. We can compute them ahead of time, and reduce the number of allocations in that method.
Commit bff61ba, while reducing allocations, caused a regression when an empty format is passed to a route. This can happen in cases where you're using an anchor tag, for example: `https://example.com/parent/575256966.#child_1032289285`. Because of this change `format` was getting sent in `parameterized_parts` when previously it was not included. This resulted in blank `format`'s being returned as `.` when if there was an extension included it would be `.extension`. Since there was no extension this caused incorrect URL's. The test shows this would result in `/posts/show/1.` instead of `/posts/show/1` which causes bad urls since the format is not present.
tested on Ubuntu Desktop 15.04
…ion_controller_overview file Rails' -> Rails" [ci skip]