braces_vs_do_end.rb

# The general convention is to use do..end for multi-line blocks and curly braces
# for single line blocks, but there is also a difference between the two that can
# be illustrated with this example:

puts [1, 2, 3].map { |k| k + 1 }
# 2
# 3
# 4
# => nil

puts [1, 2, 3].map do |k| k + 1; end
# <Enumerator:0x0000010a06d140>
# => nil

# This means that {} has a higher precedence than do  ..end, so keep that in mind
# when deciding what you want to use. P.S: One more example to keep in mind while
# you develop your preferences. The following code:

task rake: pre_rake_task do
  something
end

# Really means:

task(rake: pre_rake_task) { something }

# And this code:

task rake: pre_rake_task {
  something
}

# Really means:

task rake: (pre_rake_task { something })

# So to get the actual definition that you want, with curly braces, you must do:

task(rake: pre_rake_task) do
  something
end

# Maybe using braces for parameters is something you want to do anyways, but if
# you don 't it' s probably best  to use do .. end in these cases to avoid this
# confusion.