From: "sikachu (Prem Sichanugrist)" <s@...>
Date: 2013-11-14T03:26:46+09:00
Subject: [ruby-core:58316] [ruby-trunk - Feature #9098] Indent heredoc	against the left margin by default when "indented closing	identifier" is turned on.


Issue #9098 has been updated by sikachu (Prem Sichanugrist).


@drbrain I could, but then the code would look ugly when the non-heredoc section is well-indented, and especially if the heredoc is pretty long. Consider this example code:

    module Rails
      class CommandsTasks # :nodoc:
        attr_reader :argv

        HELP_MESSAGE = <<-EOT
    Usage: rails COMMAND [ARGS]

    The most common rails commands are:
     generate    Generate new code (short-cut alias: "g")
     console     Start the Rails console (short-cut alias: "c")
     server      Start the Rails server (short-cut alias: "s")
     dbconsole   Start a console for the database specified in config/database.yml
                 (short-cut alias: "db")
     new         Create a new Rails application. "rails new my_app" creates a
                 new application called MyApp in "./my_app"

    In addition to those, there are:
     application  Generate the Rails application code
     destroy      Undo code generated with "generate" (short-cut alias: "d")
     plugin new   Generates skeleton for developing a Rails plugin
     runner       Run a piece of code in the application environment (short-cut alias: "r")

    All commands can be run with -h (or --help) for more information.
    EOT

        COMMAND_WHITELIST = %(plugin generate destroy console server dbconsole application runner new version help)

Compared to this:

    module Rails
      class CommandsTasks # :nodoc:
        attr_reader :argv

        HELP_MESSAGE = <<-EOT
          Usage: rails COMMAND [ARGS]

          The most common rails commands are:
           generate    Generate new code (short-cut alias: "g")
           console     Start the Rails console (short-cut alias: "c")
           server      Start the Rails server (short-cut alias: "s")
           dbconsole   Start a console for the database specified in config/database.yml
                       (short-cut alias: "db")
           new         Create a new Rails application. "rails new my_app" creates a
                       new application called MyApp in "./my_app"

          In addition to those, there are:
           application  Generate the Rails application code
           destroy      Undo code generated with "generate" (short-cut alias: "d")
           plugin new   Generates skeleton for developing a Rails plugin
           runner       Run a piece of code in the application environment (short-cut alias: "r")

          All commands can be run with -h (or --help) for more information.
        EOT

        COMMAND_WHITELIST = %(plugin generate destroy console server dbconsole application runner new version help)

From the code example, you could see that it looks much nicer when it's properly indented based on the level. The heredoc doesn't feel foreign and stand out-of-place anymore.
----------------------------------------
Feature #9098: Indent heredoc against the left margin by default when "indented closing identifier" is turned on.
https://bugs.ruby-lang.org/issues/9098#change-42911

Author: sikachu (Prem Sichanugrist)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: syntax
Target version: Next Major


tl;dr: I would like to port +String#strip_heredoc+ (http://api.rubyonrails.org/classes/String.html#method-i-strip_heredoc) from Rails and enable it on `<<-` heredoc.

Hi,

I've been using here document (heredoc) for a while, and I've found out that it's very annoying that the content is always treated as flushed left. Per syntax doc:

    Note that the while the closing identifier may be indented, the content is
    always treated as if it is flush left.  If you indent the content those spaces
    will appear in the output.

So, this is the current result if you use heredoc in Ruby:

    class FancyHello
      def self.hello
        puts <<-README.inspect
          Hello
            World!
        README
      end
    end
    
    FancyHello.hello # => "      Hello\n        World!\n"

In Rails, the core team has implemented +String#strip_heredoc+, which handles this scenario by remove leading white spaces  from the string. However, not many user know that Rails has that method, and instead doing this to get around it:

    class FancyHello
      def self.hello
        puts <<-README.inspect
    Hello
      World!
        README
      end
    end
    
    FancyHello.hello # => "Hello\n  World!\n"

I really think that we could do better on this by removing the leading white spaces, matching +String#strip_heredoc+ method.

So, after the change, I want to be able to do this, and get this result:

    class FancyHello
      def self.hello
        puts <<-README.inspect
          Hello
            World!
        README
      end
    end
    
    FancyHello.hello # => "Hello\n  World!\n"

Note: the behavior on `<<HEREDOC` will stay the same, as I feel like in that case you really want the input to be flushed left.

I'll write up a patch and submit it if you think this is a good idea. Please let me know any question or concern you may have.

Thank you,

Prem


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