From: Gary Wright <gwtmp01@...>
Date: 2007-04-20T14:06:08+09:00
Subject: Re: Unless Expression Parsing


On Apr 19, 2007, at 11:50 PM, bbiker wrote:
> p (( 3 unless true))       => nil      #  you're asking for the result
> of '3 unless true', )


if 'x unless y' is a valid expression then why is the *extra* set
of parenthesis needed when that expression is used as a method argument?

foo(x unless y)     # syntax error
foo((x unless y))   # not a syntax error

This seems to be a problem with any of the statement modifier forms:
if, rescue, while, until.

Looking at parse.y it seems that the grammar differentiates between
arguments and statements.  Adding the parens forces the statement to
become an expression.