Ruby Code Formatter

The Ruby community standardized on 2-space indentation early on through the Ruby Style Guide and the original RuboCop defaults. Two-space indents keep deeply nested blocks (closures inside iterators, nested classes, when arms inside case) horizontally compact, which complements Ruby’s preference for short methods and expressive block syntax. Most popular Ruby projects, including Rails, follow this convention.

Functionally, do...end et { ... } describe the same construct — a block passed to a method — but they bind differently because of operator precedence. do...end binds loosely (so arr.each do |x| ... end.size calls .size on the result of each, not on the block’s return), while { ... } binds tightly to the nearest method call. Style guides typically reserve braces for single-line blocks and do...end for multi-line blocks.

Ruby lets you place a conditional after a statement, e.g. return nil if value.nil?. This is called the modifier form. It is syntactically a single expression, not a block, so it does not require an end. Modifier form reads naturally for short guard clauses but is generally avoided for complex conditions, where a multi-line if block is clearer.

A heredoc is a multi-line string literal opened with <<TAG and closed by a line containing only TAG. Plain <<TAG requires the closing tag to start at column zero, which clashes with indented code. <<-TAG allows the closing tag to be indented, but keeps every line of the body verbatim. <<~TAG (the squiggly heredoc, added in Ruby 2.3) removes the smallest common leading indentation from every line of the body, so the literal can match the surrounding code indent without leaking spaces into the resulting string.