From: "mame (Yusuke Endoh)" Date: 2013-12-17T12:49:02+09:00 Subject: [ruby-core:59152] [ruby-trunk - Bug #9251] ! operator has lower precedence than = in an assignment expression Issue #9251 has been updated by mame (Yusuke Endoh). I think you are confused because you know lvalue. In C, lvalue is indeed an expression. But in Ruby, "lhs" (not lvalue) is NOT an expression. This is a matter of taste of the language design. As the thought, the book may be slightly unkind if it lists "=" in the precedence table without notes. (Again, I don't have the book.) Anyway, the current behavior is useful and actually used for some people. It must not change to an inconvenient behavior just because of a philosophical reason. -- Yusuke Endoh ---------------------------------------- Bug #9251: ! operator has lower precedence than = in an assignment expression https://bugs.ruby-lang.org/issues/9251#change-43714 Author: rits (First Last) Status: Feedback Priority: Low Assignee: Category: doc Target version: ruby -v: ruby 2.0.0p353 (2013-11-22 revision 43784) [i686-linux] Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN irb(main):001:0> !a = 1 (irb):1: warning: found = in conditional, should be == => false irb(main):002:0> a => 1 ! is supposed to have higher precedence than =, so !a = 1 should be (!a) = 1, and thus an error, not !(a = 1) -- http://bugs.ruby-lang.org/