JacobNinja

# For loop
# suggested: replace with each
for i in x
end

# each_with_object mutates array
# suggested: replace with map
each_with_object([]) |list, i|
  list << i
end

JacobNinja

class RenameTableToLongerName < ActiveRecord::Migration
  def change
    remove_index :table, name: 'index_table_on_something_id'
    remove_index :table, name: 'index_table_on_something_id'
    rename_table :table, :incredibly_long_table_name_overflowing_index_length
    add_index :incredibly_long_table_name_overflowing_index_length, :something_id, name: 'index_iltnoil_on_something_id'
    add_index :incredibly_long_table_name_overflowing_index_length, :something_id, name: 'index_iltnoil_on_something_id'
  end
end

JacobNinja

jacob@Ninja:$ bin/benchmark_rails
Rehearsal ------------------------------------
 "Codeminer encountered 2 errors parsing 1711 files"
  6.520000   0.040000   6.560000 (  6.564404)

"RubyParser encountered 26 errors parsing 1711 files"
 17.110000   0.240000  17.350000 ( 17.340777)
-------------------------- total: 23.910000sec

       user     system      total        real

JacobNinja

2.1.1 :001 > def test(foo:)
2.1.1 :002?>   puts foo
2.1.1 :003?>   end
 => :test
2.1.1 :004 > test()
ArgumentError: missing keyword: foo

JacobNinja

(defn unsafe-deserialization? [node]
  (and (call-with-receiver-node? node)
       (eq-receiver? node "YAML")
       (some #(eq-method-name? node %)
             ["load" "load_documents" "load_stream" "parse_documents" "parse_stream"])))

JacobNinja

repo = Bugwatch::Repo.discover('bugwatch', Dir.pwd)
# => #<Bugwatch::Repo:0x00000101c98ae0 @name="bugwatch", @url="/Users/jacobr/code/bugwatch">
commit = repo.commits.first
# => #<Bugwatch::Commit:0x00000101ca0100 @attributes={:sha=>"d7ecd8b082906df27be6d973a196f32621d5ad1f", :message=>"add the rest of the headers", :diffs=>#<Enumerator: #<Enumerator::Generator:0x00000101ca0218>:each>, :stats=>#<Enumerator: #<Enumerator::Generator:0x00000101ca0290>:each>, :tree=>#<Bugwatch::Tree:0x00000101ca01c8 @grit=#<Grit::Tree "658dc44b7abec270b90121798e111202ac040dd9">>, :author_name=>"Jacob Richardson", :author_email=>"jacobr@groupon.com", :authored_date=>2013-07-23 12:22:49 -0600, :committer_name=>"Jacob Richardson", :committer_email=>"jacobr@groupon.com", :committed_date=>2013-07-23 12:22:49 -0600}>
commit.author_name
# => "Jacob Richardson"
commit.authored_date
# => 2013-07-23 12:22:49 -0600
commit.files
# => ["Gemfile", "Rakefile", "bugwatch.gemspec", "features/exceptions/commit_finder.feature", "features/step_defin

JacobNinja

# Example of chunking an operation that would use too much memory
# Grit is a git repository library 

all_commits = -> grit_repo {
  Enumerator.new do |y|
    total_commit_count = grit_repo.commit_count    
    # we can safely handle 500 commits in memory
    amount = 500
    offset = 0
    ((total_commit_count / amount) + 1).times do

JacobNinja

urls = ['http://www.google.com', 'http://www.github.com', 'http://www.twitter.com']
 
concurrent_url_grabber = Enumerator.new do |y|
  urls.map do |url|
    Thread.new do
      result = http_request(url)
      # Need a mutex here for multithreaded VMs
      y << result
    end
  end.each(&:join)

JacobNinja

class CommitScore

  ScoreValue = Struct.new(:email, :score)

  def initialize(commit_values)
    @commit_values = commit_values
  end

  def score
    grouped_commits_by_email.map {|(email, commits) score_value(email, commits) }

JacobNinja

def fib(n)
  if (n < 2)
    n
  else
    fib(n-1) + fib(n-2)
  end
end

JRuby 1.7.2