Forum: Ruby Require within a module: path question

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94cc3e46cfc5bc361e409e2e884ecfa4?d=identicon&s=25 Drew Olson (dfg59)
on 2007-03-06 14:59
All -

It seems to me that if I create a module, a.rb, and a script that
require's that module, b.rb, something interesting happens. In this
case, my a relies on other external files in the project, so I must
require these files within a.rb. However, I've noticed that because b
requires module a, all the require statements within the file a.rb must
be relative to b's location in the directory structure. Thus, when these
files are stored in different places, it becomes very confusing when
looking at file a.rb as to why the require statements don't seem to be
relative to that file. Is this intended functionality? Have I done
something stupid?

Thanks,
Drew
753dcb78b3a3651127665da4bed3c782?d=identicon&s=25 Brian Candler (Guest)
on 2007-03-06 15:32
(Received via mailing list)
On Tue, Mar 06, 2007 at 10:59:15PM +0900, Drew Olson wrote:
> It seems to me that if I create a module, a.rb, and a script that
> require's that module, b.rb, something interesting happens. In this
> case, my a relies on other external files in the project, so I must
> require these files within a.rb. However, I've noticed that because b
> requires module a, all the require statements within the file a.rb must
> be relative to b's location in the directory structure.

No - they just have to be relative to any of the directories in $: (the
load
path array)

On my machine I get:

$ ruby1.8 -e 'puts $:'
/usr/local/lib/site_ruby/1.8
/usr/local/lib/site_ruby/1.8/i486-linux
/usr/local/lib/site_ruby/1.8/i386-linux
/usr/local/lib/site_ruby
/usr/lib/ruby/1.8
/usr/lib/ruby/1.8/i486-linux
/usr/lib/ruby/1.8/i386-linux
.

The last entry (.) means "the current directory".

So if I do "require 'a/b'" then the system will try

/usr/local/lib/site_ruby/1.8/a/b.rb
/usr/local/lib/site_ruby/1.8/i486-linux/a/b.rb
/usr/local/lib/site_ruby/1.8/i386-linux/a/b.rb
/usr/local/lib/site_ruby/a/b.rb
/usr/lib/ruby/1.8/a/b.rb
/usr/lib/ruby/1.8/i486-linux/a/b.rb
/usr/lib/ruby/1.8/i386-linux/a/b.rb
./a/b.rb

> Thus, when these
> files are stored in different places, it becomes very confusing when
> looking at file a.rb as to why the require statements don't seem to be
> relative to that file. Is this intended functionality? Have I done
> something stupid?

If you don't want to install your own module files in one of the
locations
listed above, then install them in some other directory and use

  ruby -I /path/to/my/lib a.rb

to run the program; or else at the top of a.rb you can write

  $:.unshift("/path/to/my/lib")

In both cases this just adds additional entries to the load path.

HTH,

Brian.
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