LoadError on require './primes.rb' in terminal - ruby

Question

When I do require './primes.rb' in irb I get this:
1.9.3-p392 :004 > require './primes.rb'
LoadError: cannot load such file -- ./primes.rb
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
from (irb):4
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/bin/irb:16:in `<main>'
Here is the primes.rb document:
# primes.rb
require 'debugger'
def prime?(num)
debugger
(1..num).each do |i|
if (num % i) == 0
return false
end
end
end
def primes(num_primes)
ps = []
num = 1
while ps.count < num_primes
primes << num if prime?(num)
end
end
if __FILE__ == $PROGRAM_NAME
puts primes(100)
end
Any suggestions of how to get this to work would be greatly appreciated!
When I do require relative it gives me this:
1.9.3-p392 :010 > require_relative 'primes.rb'
LoadError: cannot infer basepath
from (irb):10:in `require_relative'
from (irb):10
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/bin/irb:16:in `<main>'
When I do the second solution below it gives me this:
1.9.3-p392 :013 > $LOAD_PATH << "."
=> ["/Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby/1.9.1", "/Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby/1.9.1/x86_64-darwin11.4.2", "/Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby", "/Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/vendor_ruby/1.9.1", "/Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/vendor_ruby/1.9.1/x86_64-darwin11.4.2", "/Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/vendor_ruby", "/Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1", "/Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/x86_64-darwin11.4.2", "."]
1.9.3-p392 :014 > require 'primes.rb'
LoadError: cannot load such file -- primes.rb
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
from (irb):14
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/bin/irb:16:in `<main>'
1.9.3-p392 :015 >
When I try it in pry:
[4] pry(main)> require_relative 'primes.rb'
LoadError: cannot infer basepath
from (pry):2:in `require_relative'
[5] pry(main)> require 'primes.rb'
LoadError: cannot load such file -- primes.rb
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
[6] pry(main)> .ls
Applications Movies git-completion.bash
Desktop Music rails_projects
Documents Pictures ruby
Downloads Public runwithfriends
Dropbox code shopify
Library dev sites
[7] pry(main)> require 'ruby/app_acad_mini_curriculum/debugging/primes.rb'
LoadError: cannot load such file -- ruby/app_acad_mini_curriculum/debugging/primes.rb
from /Users/RBonhardt/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'

Answer 1

Try require_relative
require_relative 'primes.rb'
EDIT:
Note that this will only work from within a script. If you are trying to require this script into an irb session then you will need to provide the full path to primes.rb. The reason is where irb's location is. For instance, try Dir.pwd inside irb and you will see where require_relative is attempting to search for primes.rb.
There are a couple things you could do:
# Just need to require the one file.
require_relative File.join('users', 'yourusername', 'prime_folder', 'prime.rb')
# Many files in the same folder
$LOAD_PATH << File.join('users', 'yourusername', 'prime_folder')
require 'prime.rb'
require 'another_file.rb'
Another option, one that I use, is Pry. It is like irb and is very easy to call from a script. It is a gem so:
gem install pry
At the end of your script, you could do:
if $0 == __FILE__
require 'pry'
binding.pry
end
You would then drop into an irb like REPL where you can test and debug your methods. I can't survive without it.

Answer 2

unlike ruby 1.8, you can't require a file that is in the same folder, because the current folder is not on the load path any longer.
To emulate the behavior of ruby 1.8, you could try
$LOAD_PATH << "."
require 'primes.rb'
However, the correct way to do in ruby 1.9, as #CharlesCaldwell pointed, is using relative_require.
Here is a good discussion of the best way to deal with this.
note that relative_require does not work in irb. You can check the motive on #CharlesCaldwell answer.
But looking in your task question, you should not use irb, you should use pry:
We're going to use two gems. One is called Pry, which is a replacement for irb. You'll have to gem install pry. It's not essential for debugging that you use Pry, but it will make life nicer.
Here is an example using relative require:
[fotanus#thing ~]$ cat primes.rb
# primes.rb
def prime?(num)
(1..num).each do |i|
if (num % i) == 0
return false
end
end
end
def primes(num_primes)
ps = []
num = 1
while ps.count < num_primes
primes << num if prime?(num)
end
end
if __FILE__ == $PROGRAM_NAME
puts primes(100)
end
[fotanus#thing ~]$ cat a.rb
require_relative 'primes.rb'
[fotanus#thing ~]$ ruby a.rb