Running rails generate controller Foo home results in:
class FooController < Application Controller
def home
end
end
(There's nothing on this line in the actual file, just a blank line)
Is there a purpose to this blank line?
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Neil Kelty
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2 Answers
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It's common to use a newline to indicate end of line, even for the last line. Many editors (like vi, which I use) add in this newline silently. The consensus is that text files (especially in the Unix world) should end in a newline, and there have been problems historically if it wasn't present. Why should text files end with a newline?
The tool I used to count the lines in a file "wc" just counts the newlines in a file, so without that trailing newline it would show 3 instead of 4.
It also improves the readability of the templates used in the generator. Consider: https://github.com/rails/rails/blob/master/railties/lib/rails/generators/rails/controller/templates/controller.rb
To remove the trailing newline, that template would have the last line of:
end<% end -%>
instead of:
end
<% end -%>
That seems less readable to me.
The discussion below refers to a blank line earlier in the file, instead of the trailing newline character.
It was an oversight and fixed in a later version of rails.
You can see in the commit history here where the blank lines get removed:
This is the commit where it was removed:
Remove redundant blank line at the bottom
It also shows you why it was there, previously they were just adding a blank line after each action.
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Shawn Balestracci
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Can you point to the specific commit? There are a few newline related commits, but none that I can see about the file ending. – Simon Perepelitsa Apr 18 '13 at 05:04
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This commit removes newline after the final action. There is still one at the end of the file. – Simon Perepelitsa Apr 18 '13 at 05:20
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What version of rails are you using? I tried several and none had a trailing newline. – Shawn Balestracci Apr 18 '13 at 05:35
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The latest Rails 3.2.13. Are you sure we are talking about the same newline? I mean the newline right at the end of a file. (See snippet in the question above.) – Simon Perepelitsa Apr 18 '13 at 05:42
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Hmm, There's no newline when I generate a controller in 3.2.13 wc ap/controllers/foo_controller.rb 4 8 65 app/controllers/foo_controller.rb – Shawn Balestracci Apr 18 '13 at 05:47
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There is if you have 4 lines for 1 controller and 1 action. This is what I mean: `ruby -e 'p File.read("app/controllers/foo_controller.rb").end_with?("\n")'` outputs true. – Simon Perepelitsa Apr 18 '13 at 07:17
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It is a common practice to end a file with a newline when keeping your source code in SCM such as git. Suppose, you add something at the end and commit the changes. Now compare the diffs in two cases.
1) Ending with newline:
--- foo_controller.rb 2013-04-18 09:14:48.000000000 +0800
+++ foo_controller2.rb 2013-04-18 09:15:10.000000000 +0800
@@ -1,4 +1,7 @@
class FooController < ApplicationController
def home
end
-end
\ No newline at end of file
+end
+
+p FooController.methods
\ No newline at end of file
2) No newline:
--- foo_controller.rb 2013-04-18 09:16:28.000000000 +0800
+++ foo_controller2.rb 2013-04-18 09:16:35.000000000 +0800
@@ -2,3 +2,5 @@
def home
end
end
+
+p FooController.methods
You see that diff treats "end" and "end\n" as two different lines which causes less clean view in the first case.
Simon Perepelitsa
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