Issue #20518 has been reported by akr (Akira Tanaka). ---------------------------------------- Bug #20518: Escaped-newline in %W https://bugs.ruby-lang.org/issues/20518 * Author: akr (Akira Tanaka) * Status: Open * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- I found an escaped-newline in %W literal is interpreted as a newline character. ``` % ./ruby -e ' p %W[a\ b]' ["a\nb"] ``` I expected it to be interpreted as a line continuation but actually not. I'm considering to describe `\<newline>` as a kind of escape sequence in the document. (Related to https://bugs.ruby-lang.org/issues/20503#note-4 ) Unfortunately, this behavior contradicts: `\<newline>` doesn't behave as usual escape sequences. Note that %W is interpolable string-array literal. https://docs.ruby-lang.org/en/master/syntax/literals_rdoc.html#label-25w+and... "interpolable" means that interpolation and escape sequences are enabled. Other escape sequences and interpolation work well. ``` % ./ruby -e ' p %W[a\ b c\x21d e#{6*7}f]' ["a\nb", "c!d", "e42f"] ``` `\x21` is interpreted as "!" and `#{6*7}` is iterpreted as "42". It is the usual interpretation of escape sequences and interpolation. But `\<newline>` is interpreted as "\n". It is not the usual interpretation of escape sequences (line continuation). It is interpreted as a line continuation in a double-quoted string: ``` % ./ruby -e ' p %Q[a\ b c\x21d e#{6*7}f]' "ab c!d e42f" ``` `\<newline>` is interpreted as empty (line continuation) as expected. `\x21` is interpreted as "!" and `#{6*7}` is interpreted as "42". I found this behavior changed between Ruby 1.8.0 and 1.8.1. Ruby 1.8.0 interprets `\<newline>` as line continuation. ``` % ruby-1.8.0 -e ' p %W[a\ b c\x21d e#{6*7}f]' ["ab", "c!d", "e42f"] % ruby-1.8.1 -e ' p %W[a\ b c\x21d e#{6*7}f]' ["a\nb", "c!d", "e42f"] ``` I think this is the commit to change the behavior. ``` commit e168b64b03403fb4efbd8dcbbdaeed83710b4d39 0d1896a88fe091000ce0d9c8ef3cf7ef1e2e991b Author: Nobuyoshi Nakada <nobu@ruby-lang.org> Date: 2003-09-04 14:59:43 +0000 * parse.y (tokadd_string): newlines have no special meanings in %w/%W, otherwise they are ignored only when interpolation is enabled. [ruby-dev:21325] git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@4496 b2dd03c8-39d4-4d8f-98ff-823fe69b080e ``` I read the discussion from [ruby-dev:21325]. https://public-inbox.org/ruby-dev/5FD2F0CF7F5D7F44B00F36870B9E78B508DE5071@S... It discusses about %w. %W is not considered well. The behavior of %w is also changed between Ruby 1.8.0 and 1.8.1. ``` % ruby-1.8.0 -e ' p %w[a\ b c\x21d e#{6*7}f]' ["ab", "c\\x21d", "e#{6*7}f"] % ruby-1.8.1 -e ' p %w[a\ b c\x21d e#{6*7}f]' ["a\nb", "c\\x21d", "e#{6*7}f"] ``` I understand the intent of this behavior for %w: it makes it possible to include white spaces in the word. Without this behavior, there is no way to include a newline character in the word. But I don't understand the intent for %W. Including a newline character using `\n` is possible because escape sequences are enabled. ``` % ./ruby -v ruby 3.4.0dev (2024-05-25T10:15:25Z master 0bae2f0002) [x86_64-linux] ``` -- https://bugs.ruby-lang.org/