and is the same as && but with lower precedence. They both use short-circuit evaluation. WARNING: and even has lower precedence than = so you’ll usually want to avoid and. An example when and should be used can be found in the Rails Guide under “Avoiding Double Render Errors”.
Use next: (1..10).each do |a| next if a.even? puts a end prints: 1 3 5 7 9 For additional coolness check out also redo and retry. Works also for friends like times, upto, downto, each_with_index, select, map and other iterators (and more generally blocks). For more info see http://ruby-doc.org/docs/ProgrammingRuby/html/tut_expressions.html#UL.
Usually I do: rspec ./spec/controllers/groups_controller_spec.rb:42 Where 42 represents the line of the test I want to run. You can also use tags. See here. Using bundle exec: bundle exec rspec ./spec/controllers/groups_controller_spec.rb:42
For those who may be confused by the accepted answer, as I was, you also need to have the ruby headers installed [ruby-devel]. The article that saved my hide is here. And this is the revised solution (note that I’m on Fedora 13): yum -y install gcc mysql-devel ruby-devel rubygems gem install -y mysql — … Read more
alias_method can be redefined if need be. (it’s defined in the Module class.) alias‘s behavior changes depending on its scope and can be quite unpredictable at times. Verdict: Use alias_method – it gives you a ton more flexibility. Usage: def foo “foo” end alias_method :baz, :foo
In a case statement, a , is the equivalent of || in an if statement. case car when ‘toyota’, ‘lexus’ # code end Some other things you can do with a Ruby case statement
array = array.uniq uniq removes all duplicate elements and retains all unique elements in the array. This is one of many beauties of the Ruby language.
It appears that the :include functionality was changed with Rails 2.1. Rails used to do the join in all cases, but for performance reasons it was changed to use multiple queries in some circumstances. This blog post by Fabio Akita has some good information on the change (see the section entitled “Optimized Eager Loading”).
How about: Dir[“/path/to/directory/*.rb”].each {|file| require file }
Use gem environment to find out about your gem environment: RubyGems Environment: – RUBYGEMS VERSION: 2.1.5 – RUBY VERSION: 2.0.0 (2013-06-27 patchlevel 247) [x86_64-darwin12.4.0] – INSTALLATION DIRECTORY: /Users/ttm/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0 – RUBY EXECUTABLE: /Users/ttm/.rbenv/versions/2.0.0-p247/bin/ruby – EXECUTABLE DIRECTORY: /Users/ttm/.rbenv/versions/2.0.0-p247/bin – SPEC CACHE DIRECTORY: /Users/ttm/.gem/specs – RUBYGEMS PLATFORMS: – ruby – x86_64-darwin-12 – GEM PATHS: – /Users/ttm/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0 – /Users/ttm/.gem/ruby/2.0.0 … Read more