Misc #19155: documentation of Pathname#join with absolute path

• Status: Closed
• Assignee: -

[colorbox (box color)]

Pathname#join ignores previous directory name before absolute path

Is this intentional?

irb(main):002:0> require 'pathname'
=> true
irb(main):003:0> Pathname('/foo').join('bar', 'baz')
=> #<Pathname:/foo/bar/baz>
irb(main):004:0> Pathname('/foo').join('bar', '/baz')
=> #<Pathname:/baz>
irb(main):005:0> 

➜✗ ruby -v
ruby 3.0.4p208 (2022-04-12 revision 3fa771dded) [x86_64-darwin19]

I found that this behavior is intentional from test code but I cannot found reason.
https://github.com/ruby/pathname/blob/master/test/pathname/test_pathname.rb#L248-L261

There was no description of this behavior in the documentation.

[sawa (Tsuyoshi Sawada)]

There is a description.

The doc https://docs.ruby-lang.org/ja/latest/class/Pathname.html#I_JOIN says:

path0 = Pathname("/usr")                # Pathname:/usr
path0 = path0.join("bin/ruby")          # Pathname:/usr/bin/ruby
   # 上記の path0 の処理は下記の path1 と同様のパスになります
path1 = Pathname("/usr") + "bin/ruby"   # Pathname:/usr/bin/ruby
path0 == path1                          #=> true

where "上記の path0 の処理は下記の path1 と同様のパスになります" translates to English as "the path of path0 above is handled on a par with path1 below", which means that join follows the specification of +. And here https://docs.ruby-lang.org/ja/latest/class/Pathname.html#I_--2B it says:

self + other -> Pathname[permalink][rdoc][edit]
self / other -> Pathname
パス名を連結します。つまり、other を self からの相対パスとした新しい Pathname オブジェクトを生成して返します。
other が絶対パスなら単に other と同じ内容の Pathname オブジェクトが返されます。

where "other が絶対パスなら単に other と同じ内容の Pathname オブジェクトが返されます。" translates to English as "if other is an absolute path, then simply a Pathname object with the same content as other would be returned".

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset git|b8a73e704ddc77db36317dda293e99fb0ee641f4.

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[ruby/pathname] [Misc #19155] [DOC] Addion of absolute paths

https://github.com/ruby/pathname/commit/3cb5ed2576