advantage of tap method in ruby

Question

I was just reading a blog article and noticed that the author used tap in a snippet something like:

user = User.new.tap do |u|
  u.username = \         


        

Answer 1

This can be useful with debugging a series of ActiveRecord chained scopes.

User
  .active                      .tap { |users| puts "Users so far: #{users.size}" } 
  .non_admin                   .tap { |users| puts "Users so far: #{users.size}" }
  .at_least_years_old(25)      .tap { |users| puts "Users so far: #{users.size}" }
  .residing_in('USA')

This makes it super easy to debug at any point in the chain without having to store anything in in a local variable nor requiring much altering of the original code.

And lastly, use it as a quick and unobtrusive way to debug without disrupting normal code execution:

def rockwell_retro_encabulate
  provide_inverse_reactive_current
  synchronize_cardinal_graham_meters
  @result.tap(&method(:puts))
  # Will debug `@result` just before returning it.
end