How to build a portable absolute path in Ruby?

Question

Let's assume a script needs access a directory, say /some/where/abc on an "arbitrary" OS. There are a couple options to build the path in Ruby:

• File.join('', 'some', 'where', 'abc')
• File.absolute_path("some#{File::SEPARATOR}where#{File::SEPARATOR}abc", File::SEPARATOR)
• Pathname in the standard API

I believe the first solution is clear enough, but idiomatic. In my experience, some code reviews ask for a comment to explain what it does...

The Question

Is there a better way to build an absolute path is Ruby, where better means "does the job and speaks for itself"?

Answer 1

What I would pick up if I was doing a code review is that on Windows /tmp is not necessarily the best place to create a temporary directory, and also the initial '', argument is perhaps not obvious to the casual reviewed that it creates <nothing>/tmp/abc. Therefore, I would recommend this code:

File.join(Dir.tmpdir(), 'abc')

See Ruby-doc for an explanation.

UPDATE

If we expand the problem to a more generic solution that does not involve using tmpdir(), I cannot see a way round using the initial '' idiom (hack?). On Linux this is not too much of a problem, perhaps, but on Windows with multiple drive letters it will be. Furthermore, there does not appear to be a Ruby API or gem for iterating the mount points.

Therefore, my recommendation would be to delegate the mount point definition to a configuration option that might be '/' for Linux, 'z:/' for Windows, and smb://domain;[email protected]/mountpoint for a Samba share, then use File.join(ProjectConfig::MOUNT_POINT, 'some', 'where', 'abc').