Using do block vs brackets {}

Question

New to ruby, put on your newbie gloves.

Is there any difference (obscure or practical) between the following two snippets?

my_array = [:uno, :dos, :tres]
my_array.each { |item| 
    puts item
}

my_array = [:uno, :dos, :tres]
my_array.each do |item| 
    puts item
end

I realize the bracket syntax would allow you to place the block on one line

my_array.each { |item| puts item }

but outside of that are there any compelling reasons to use one syntax over the other?

Answer 1

Ruby cookbook says bracket syntax has higher precedence order than do..end

Keep in mind that the bracket syntax has a higher precedence than the do..end syntax. Consider the following two snippets of code:

1.upto 3 do |x|
  puts x
end

1.upto 3 { |x| puts x }
# SyntaxError: compile error

Second example only works when parentheses is used, 1.upto(3) { |x| puts x }

Answer 2

Generally the convention is to use {} when you are doing a small operation for example a method call or a comparison, etc. so this makes perfect sense

some_collection.each { |element| puts element }

But if you have slightly complex logic that goes to multiple lines then use do end like

1.upto(10) do |x|
  add_some_num = x + rand(10)
  puts '*' * add_some_num
end

Basically it comes down to, if your block logic goes to multiple lines and cannot be fitted on the same line then use 'do end' and if your block logic is simple and just a simple/single line of code then use {}.