Bug #13908: Result of Pathname#dirname / File.dirname handling of paths with trailing File::SEPARATOR is surprising

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.4.1p111
• Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN

[davemyron (Dave Myron)]

Given File.dirname("/some/folder/") the result of /some is very surprising because the path is "obviously" a directory without a file specified. (I got bit by this today… yes, I needed more tests)

My expectation was that it would return /some/folder. My expectation seems consistent with the method's documentation which states "Returns all components of the filename given in file_name except the last one." – the "last one" should be the item after the last File::SEPARATOR ("/" on my system)

What is the reasoning for the above being the behavior?

[davemyron (Dave Myron)]

• Subject changed from Result of Pathname#dirname / File.dirname handling of paths with trailing slashes is surprising to Result of Pathname#dirname / File.dirname handling of paths with trailing File::SEPARATOR is surprising

[davemyron (Dave Myron)]

• Description updated (diff)

[davemyron (Dave Myron)]

• Description updated (diff)

[rocifier (Ryan O'Connor)]

davemyron (Dave Myron) wrote:

Given File.dirname("/some/folder/") the result of /some is very surprising because the path is "obviously" a directory without a file specified. (I got bit by this today… yes, I needed more tests)

My expectation was that it would return /some/folder. My expectation seems consistent with the method's documentation which states "Returns all components of the filename given in file_name except the last one." – the "last one" should be the item after the last File::SEPARATOR ("/" on my system)

What is the reasoning for the above being the behavior?

The path is obvious a directory.. true. However, the docs says to call the method with a filename, not a directory name. I'm not quite sure what you would be trying to achieve by calling it with just a directory name. Perhaps you intend to use Pathname.new("/some/folder/") instead?

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset trunk|r59933.

---

file.c: [DOC] separators at dirname and basename

• file.c (rb_file_s_basename, rb_file_s_dirname): [DOC] state
  that trailing separators will be stripped first, like as
  basename(1) and dirname(1). [ruby-core:82828] [Bug #13908]