git: clear credentials cache

Clear git credentials cache:

cd .git-credential-cache/
rm -rf .git-credential-cache

Ruby: Metaprogramming

https://rubymonk.com/learning/books/2-metaprogramming-ruby/chapters/32-introduction-to-metaprogramming/lessons/75-being-meta

Metaprogramming is the act of writing code that operates on code rather than on data. This involves inspecting and modifying a program as it runs using constructs exposed by the language.

Rails - helper & helper_method

Rails - helper & helper_method

http://stackoverflow.com/questions/3992659/in-rails-what-exactly-do-helper-and-helper-method-do

Rails: Converting an array of objects to activerecordrelation

http://stackoverflow.com/a/24448317

Rails: How to remove items from a ActiveRecord Query's Resultset

http://stackoverflow.com/questions/7514620/how-to-remove-items-from-activerecord-query-resultset

User 'reject'

Ruby: Checking if a variable is defined?

http://stackoverflow.com/a/288726