From the Elements of Ruby Style
Ruby allows you to leave out parenthesis, in general, resist this
Parenthesis make the code easier to
follow. General Ruby style is to use
them, except in the following cases:
- Always leave out empty parentheses
- The parentheses can be left out of a single command that is surrounded by
ERb delimiters — the ERb markers make
sure the code is still readable
- A line that is a single command and a single simple argument can be
written without the parenthesis.
Personally, I find that I do this less
and less, but it’s still perfectly
readable. I tend not to like single
lines in regular ruby code that have
multiple arguments and no parentheses.
- A lot of Ruby-based Domain Specific Languages (such as Rake) don’t use
parenthesis to preserve a more natural
language feel to their statements.