Wouldn't it be a little confusing to remember that __FILE__ is uppercase and
__dir__ is downcase? Doesn't sound very POLS to me...

//Magnus Holm


On Wed, Aug 19, 2009 at 16:57, Yutaka HARA <redmine / ruby-lang.org> wrote:

> Feature #1961: Kernel#__dir__
> http://redmine.ruby-lang.org/issues/show/1961
>
> Author: Yutaka HARA
> Status: Open, Priority: Normal
>
> = Proposal
>
>  Kernel#__dir__
>  returns the value of File.dirname(__FILE__)
>
> According to the google code search, about 60% of uses of __FILE__
> are of the form File.dirname(__FILE__). Ruby 1.9.2 provides
> require_relative for this problem; but File.dirname(__FILE__) is
> not always used for requiring ruby scripts, but also for reading
> data files. __dir__ helps these cases.
>
> (Note: my proposal does not include __dir_dir__ this time :-)
> It should be discussed in another threads)
> Related ticket: http://redmine.ruby-lang.org/issues/show/642
>
> = Problem
>
> File.dirname(__FILE__) is frequently used and too long.
>
> = Analysis
>
> There are 222 uses of __FILE__ listed by the google code search,
> classified into these categories:
>
>  (A) 30.6% (68) are used with require and File.dirname.
> In Ruby 1.9.2, this case is supported by require_relative.
>
>  (B) 31.1% (69) are with File.dirname, but not with require.
> For example, reading data files of unit tests.
>
>  (C) 21.6% (48) are the idiom, $0 == __FILE__.
>
> B is as many as A (and even more than C), so it is reasonable to
> add a shortcut for File.dirname(__FILE__) in addition to require_relative.
>
> * code: http://gist.github.com/170336
> * result: http://route477.net/files/__file__.html
>
> = Solutions
>
> (1) add a toplevel constant __DIR__
> pros: looks like __FILE__
> cons: adding new keyword
>
> (2) add Kernel#__DIR__
> pros: no new keyword
> cons: it should have a lower-case name (like 1.9's __method__),
> because it is not a constant but a method.
>
> (3) add Kernel#__dir__
> pros: no new keyword, and it is clearer than (4) that it has
> some associations with __FILE__.
>
> (4) make __FILE__ to the default argument of File.dirname
> pros: no new keyword nor new method
> cons: it is not clear that 'File.dirname' is expanded to
> the path of directory of __FILE__.
>
> = Conclusion
>
> I think (3) (Kernel#__dir__) is the best.
>
> Thanks,
> --
> yhara (Yutaka HARA)
> http://route477.net/
>
>
> ----------------------------------------
> http://redmine.ruby-lang.org
>
>