Delta Flora

DESCRIPTION

Delta-flora is set of classes and functions which enable interactive analysis of Ruby code histories in an interactive Ruby shell.

The primary class is named Repository. It builds a representation of the history of all Ruby method changes in a repository. These changes are called events. You can access them in irb like this:

  2.0.0p0 :001 > load 'repository.rb'
  2.0.0p0 :002 > es = Repository.new('/Users/joe-shmoe/Projects/rails').events

Each event describes the state of a method at a particular point in time. There are three types of event: added, changed, and deleted.

Regardless of type, each event contains the following information:

field	description
type	added, changed, or deleted
commit	sha1 of the git commit for the code change
date	date of the commit
file_name	name of the file containing the method
committer	author of the commit
class_name	name of the class containing the method
method_name	name of the method (fully-qualified by class and module name)
start_line	start line of the method at that commit
end_line	end line of the method at that commit

The file analytics.rb contains a set of functions that can be used to analyze histories. Here is function which produces a frequency histogram of the classes by the number of methods they contain:

  def class_method_count_freq es
    es.group_by(&:class_name)
      .map {|_,v| v.map(&:method_name).uniq.count }
      .freq
  end

Let's do that analysis:

2.0.0p0 :003 > load 'analytics.rb'
2.0.0p0 :004 > class_method_count_freq(es)

 => [[1, 1393], [2, 937], [3, 576], [4, 442], [5, 371], [6, 253], [7, 208], [8, 176] .. ]

Events are created from the repository using the --topo-order flag on git log. This ordering puts branches one after another rather than using strict date ordering. This allows us to do simple analyses like seeing how method lengths have changed over time without the complications that we would have with strict date ordering. Although branch information is disgarded in this linear history, you can expect runs of events within branches to be date ordered.

USAGE

Use of delta-flora is easy. The steps in the description should get you started. But, it's important to note that the first time you run delta-flora on a repo it takes considerable amount of time rip the repo and produce method events.

To make use easier, the Repository class has been designed to check for a file named methodevents.csv in the repository directory. If it exists and there are no commits with a later datestamp in the repo, then methodevents.csv is assumed to be current and it is loaded. If methodevents.csv does not exist or it is out of date, Repository rips the repo and produces a methodevents.csv file.

The phrase es = Repository.new('some repostory path').events is a bit verbose, so delta-flora supplies a convenience method that has the same effect:

  es = load_events('some repository path')

NAMING

Delta Flora is the name of an album by Hughscore: a group formed by the late Hugh Hopper of Soft Machine. I chose the name because its literal meaning is the flowering/bountiful mouth of a river. It seemed like a good name for a tool that produces useful information from repositories. Aside from that, the pun on the word delta with regard to version control systems was too good to pass up.

REQUIREMENTS

Ruby 2.6 or greater

LICENSE

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

michaelfeathers / delta-flora