Ruby Styleguide

We generally follow the Ruby Style Guide maintained by bbatsov, with the following exceptions:

Coercing Boolean Values

It is acceptable to use !! to coerce a value to be true or false.

Collections

It is acceptable to have a comma after the last item of an Array or Hash literal.

Exceptions

raise is acceptable to use instead of fail.

Lambdas

Stabby lambdas (->) are preferred for both single line and multi-line blocks. They solve a syntactic ambiguity with pipes being used in defaults for arguments.

Line Length

Limit lines to 120 characters.

Perl-ish Variables

Ruby allows several special variables which it primarily inherited from Perl. These are a $ followed by one other character. Avoid their use, except for the following, as they are better known than any alternative:

• $? which returns Process::Status for last executed child process (e.g., from ls -l).
• $! which returns the pending exception. This is the second parameter to a raise statement.

Use named captures and Regexp#match rather than Perl variables ($~, $1). See Refactoring Regular Expressions with Ruby 1.9 Named Captures.

Note that =~ is allowed when you don't have any captures. Regexp.last_match is not allowed.

Post-loop conditionals

While a loop … break construction is preferred, post-loop conditionals are acceptable.

While/Until

While we prefer single-line while/until (https://github.com/bbatsov/ruby-style-guide#while-as-a-modifier), use common sense if the line length gets too long. Break it into a multi-line loop.

Long Line Method Invocation

Prefer normal indent over indenting to the first paren:

# bad
def this_is_especially_bad_with_long_method_names(first_attribute: variable_foo,
                                                  second_attribute: variable_bar,
                                                  third_attribute: variable_baz)
end

# good (normal indent)
def send_mail(source)
  Mailer.deliver(
    to: 'bob@example.com',
    from: 'us@example.com',
    subject: 'Important message',
    body: source.text
  )
end

No one likes to wrangle whitespace. Ref: https://github.com/bbatsov/ruby-style-guide#no-double-indent