Question

I’ve been working on my first Ruby project, and in the process of trying to organize my files into different directories, I’ve run into trouble with having .rb files load non-ruby files (e.g. .txt files) local to themselves.

For example, suppose a project has the following structure:

myproject/
    bin/
        runner.rb
    lib/
        foo.rb
        fooinfo.txt
    test/
        testfoo.rb

And the file contents are as follows:

runner.rb

require_relative '../lib/foo.rb'

foo.rb

File.open('./fooinfo.txt') do |file|
    while line = file.gets
        puts line
    end
end

If I cd to lib and run foo.rb, it has no trouble finding fooinfo.txt in its own directory and printing its contents.
However, if I cd to bin and run runner.rb, I get

in `initialize': No such file or directory - ./fooinfo.txt (Errno::ENOENT)

I assume this is because File.open searches relative to whatever directory the top level program is run from.
Is there a way to ensure that foo.rb can find fooinfo.rb regardless of where it is run/required from (assuming that foo.rb and fooinfo.rb always maintain the same location relative to eachother)?
I’d like to be able to run foo.rb from bin/runner.rb, and a test file in test/, and have it be able to find fooinfo.txt in both cases.

Ideally, I’d like to have a solution that would work even if the entire myproject directory were moved.

Is there something like require_relative that can locate a non-ruby file?

Answer 1

In this case, the simplest thing is to just change

File.open('./fooinfo.txt')

to

File.open('../lib/fooinfo.txt')

That will work from from any project subdirectory directly under your project root (including lib/).

The more robust solution, useful in larger projects, is to have a PROJECT_ROOT constant that you can use from anywhere. If you have lib/const.rb:

module Const
  PROJECT_ROOT = File.expand_path("..", File.dirname(__FILE__))
end

Then (assuming you’ve requireed that file) you can use:

File.open(Const::PROJECT_ROOT + '/lib/fooinfo.txt')