From: Yukihiro Matsumoto Date: 2006-03-16T15:14:01+09:00 Subject: Re: [ ruby-Bugs-3843 ] "not" operator used in expression that is a method parameter can generate syntax error Hi, In message "Re: [ ruby-Bugs-3843 ] "not" operator used in expression that is a method parameter can generate syntax error" on Thu, 16 Mar 2006 13:29:20 +0900, 卜部昌平 writes: |Nobu, you are not answering to the question.... You have to unveil why |that syntax is a statement rather than an expression, and why |statements are not allowed as an argument. OK. Keyword logical operators (and, or, not) are far lower precedence than comma, even lower than method calls without argument parentheses (in parser, they are called as commands), so that they are not allowed be a part of argument expression. matz.