Reek 2 just got released!

A couple of days ago we released the new and extremely shiny Reek version 2 to the world!

Reek is a static code analyzer for Ruby detecting so called code smells. Those code smells range from rather trivial ones like UncommunicativeParameterName or TooManyMethods to high-level code smells like FeatureEnvy or DataClump.

In the most simple use case you can just run

reek my/source/files


echo "def dirty(x,y,z); puts 'hossa!'; end" | reek

 So what has happened since 1.*?

There are way too many significant changes to list them all so I restrict this list to my favourite ones (excluding the countless bugfixes):


Parsing with the parser gem allows us to support all major Ruby versions:


We deliberately dropped support for 1.8.

 New smell detectors

We introduced 2 new smell detectors:

 Revised configuration handling

We completely revised our configuration handling, basically there are 3 ways of passing Reek a configuration file:

  1. Using the cli -c switch.
  2. Having a file ending with .reek either in your current working directory or in a parent directory.
  3. Having a file ending with .reek in your HOME directory.

This means that Reek no longer tries to nest configuration files, but instead from Reek‘s point of view there exists only one configuration file and one configuration.

Another cool feature is support for detecting specific smells like this:

reek lib/ --smell FeatureEnvy

This can be very helpful when refactoring when you want to focus on one group of problems.

And last but not least smell detectors can be configured or disabled in code comments like this (in addition to Reek’s regular configuration mechanism):

# This method smells of :reek:NestedIterators
def smelly_method foo
  foo.each {|bar| bar.each {|baz| baz.qux}}

 CLI / Output / UX

We completely restructured and revised the command line interface for Reek:

 rspec matchers

We made the reek_of / reek_only_of rspec matchers a little smarter - you can still just do something like:

expect(src).not_to reek_of(:UncommunicativeParameterName)

but if you really want to be more specific about this you can now add a hash of “smell_details” reek_of will check for as well like this:

expect(src).not_to reek_of(:UncommunicativeParameterName, name: 'x1' )

You can check out the details here.


Now read this

Reek 3 has been released!

My beloved Reek gem has come quite a long way. During the last months we refactored so much of the source code that it almost feels like a new and shiny gem. Right after the release of Reek 2 we started to work on Reek 3 which we... Continue →