LOOPS:

1. Never use unless with else. Rewrite these with the positive case first.
   BAD
   unless success?
   message = 'FAIL'
   else
   message = 'PASS'
   end

GOOD
if success?
message = 'PASS'
else
puts 'failure'message = 'FAIL'
end

1. Use unless instead of if for negative conditions.
   BAD
   unless x == 10
   ...
   end

GOOD
if x != 10
...
end

BAD
unless x < 10
...
end

GOOD
if x >= 10
...
end

1. Don't use parentheses around the condition of an if/unless/while.
   BAD
   if (x > 10)
   ...
   end

GOOD
if x > 10
...
end

1. Prefer next in loops instead of conditional blocks.
   BAD
   [0, 1, 2, 3].each do |item|
   if item > 1
   puts item
   end
   end

GOOD
[0, 1, 2, 3].each do |item|
next unless item > 1
puts item
end

STATEMENTS:

1. The and, or, and not keywords are banned. It's just not worth it. Always use &&, ||, and ! instead.

2. Do not include space inside block parameter pipes. Include one space between parameters in a block. Include one space outside block parameter pipes.
   BAD
   {}.each { | x, y |puts x }

GOOD
{}.each { |x, y| puts x }

1. Don't use extra whitespace in range literals.
   BAD
   (0 ... coll).each do |item|

GOOD
(0...coll).each do |item|

1. Omit parentheses for a method call if the method accepts no arguments.
   BAD
   nil?()

GOOD
nil?

1. Use shorthand self assignment operators whenever applicable
   BAD
   x = x + y
   x = x * y
   x = x**y
   x = x / y
   x = x || y
   x = x && y

GOOD
x += y
x *= y
x **= y
x /= y
x ||= y
x &&= y

STRINGS:

1. Omit whitespace when doing string interpolation.
   BAD
   var = "This #{ foobar } is interpolated."

GOOD
var = "This #{foobar} is interpolated."

1. Don’t use Object#to_s on interpolated objects. It’s invoked on them automatically.
   BAD
   message = "This is the #{result.to_s}."

GOOD
message = "This is the #{result}."

GENERAL:

1. Never leave commented-out code in our codebase.

2. Use snake_case for naming files and directories

3. Use block comments if comments are more than 2 lines:
   BAD

1st comment line

2nd comment line

3rd comment line

GOOD
=begin
1st comment line
2nd comment line
3rd comment line
=end

FUNCTIONS:

1. Function should not accept more than 3 parameters.
   More than 3 values should be sent in hash.
   BAD
   def obliterate(things, gently = true, except = [], at = Time.now)
   ...
   end

GOOD
def obliterate(things, options = {})
options = {
:gently => true, # obliterate with soft-delete
:except => [], # skip obliterating these things
:at => Time.now, # don't obliterate them until later
}

...

end

1. A function can return only 2 values. If more than 2 values needs to be returned, use hash