I use:
rvm 1.25.19 (stable)
ruby 1.9.3p545
I install gem rake command
gem install rake
I understand that $LOAD_PATH should contain the paths:
~/.rvm/rubies/ruby1.9/gems/rake/lib
~/.rvm/rubies/ruby1.9/gems/rake/bin
I execute command:
ruby -e 'puts $LOAD_PATH'
output:
/home/slip/.rvm/rubies/ruby-1.9.3-p545/lib/ruby/site_ruby/1.9.1
/home/slip/.rvm/rubies/ruby-1.9.3-p545/lib/ruby/site_ruby/1.9.1/x86_64-linux
/home/slip/.rvm/rubies/ruby-1.9.3-p545/lib/ruby/site_ruby
/home/slip/.rvm/rubies/ruby-1.9.3-p545/lib/ruby/vendor_ruby/1.9.1
/home/slip/.rvm/rubies/ruby-1.9.3-p545/lib/ruby/vendor_ruby/1.9.1/x86_64-linux
/home/slip/.rvm/rubies/ruby-1.9.3-p545/lib/ruby/vendor_ruby
/home/slip/.rvm/rubies/ruby-1.9.3-p545/lib/ruby/1.9.1
/home/slip/.rvm/rubies/ruby-1.9.3-p545/lib/ruby/1.9.1/x86_64-linux
why path to gem 'rake' don't add?
Installing a gem in Ruby doesn’t automatically add that gem’s files to the load path. When you require a file, first the existing load path is searched and if no matching file is found then Rubygems searches the installed gems for the file. If such a gem is found, then it is activated, which is when the gem’s lib directory is added to the load path.
Here’s an example using the Haml gem:
puts "Before:"
puts $LOAD_PATH
puts
require 'haml'
puts "After:"
puts $LOAD_PATH
This produces:
Before:
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/site_ruby/1.9.1
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/site_ruby/1.9.1/x86_64-darwin10.8.0
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/site_ruby
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/vendor_ruby/1.9.1
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/vendor_ruby/1.9.1/x86_64-darwin10.8.0
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/vendor_ruby
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/x86_64-darwin10.8.0
After:
/Users/matt/.rvm/gems/ruby-1.9.3-p448/gems/tilt-1.4.1/lib
/Users/matt/.rvm/gems/ruby-1.9.3-p448/gems/haml-4.0.5/lib
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/site_ruby/1.9.1
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/site_ruby/1.9.1/x86_64-darwin10.8.0
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/site_ruby
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/vendor_ruby/1.9.1
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/vendor_ruby/1.9.1/x86_64-darwin10.8.0
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/vendor_ruby
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1
/Users/matt/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/x86_64-darwin10.8.0
See how the lib directories for Tilt (which is a dependency of Haml) and Haml have been added to the start of the load path.
In the case of some gems, such as Rake, this is complicated by the fact they are part of the standard library and so are already on the load path. If you changed the example above to use require 'rake' then you wouldn’t see any change in the load path. In this situation you can specify you want to use the gem version with the gem method. This activates the gem in question, placing its lib directory at the start of the load path so when you later call require you will load the correct version.
For example, this script
require 'rake'
puts Rake::VERSION
produces 0.9.2.2 with Ruby 1.9.3, as that is the version of Rake included in the standard library. However this script:
gem 'rake'
require 'rake'
puts Rake::VERSION
produces 10.1.1, since that is the current highest version of the Rake gem installed on my system. You can also specify a particular gem version by providing a second argument to gem (this is the same syntax as used in Gemfiles). Note that the gem method doesn’t require any files, you have to do that as a separate step.
Related
I'm writing a batch script as a setup for a ruby program I'm writing. It needs to be able to
a. Make sure Ruby is installed on the user's computer (and if not point them to the ruby download page)
b. make sure the ruby "yaml" gem is installed, which is a prerequisite for it. I've tried
gem install yaml
in the batch script to no avail. How can I write a batch script that will do these two things?
As far as I know, there is no yaml gem. Although it must be required in code that uses it, it is distributed as part of a Ruby installation. Try this:
ruby -ryaml -e"puts 'YAML found'"
It should work; and if you change the -r token to some nonexistent gem, you'll see an exception raised.
Instead of writing your own script, you could use bundler and create a gemfile. This way people can install all the gems on any operating system.
Example:
require 'rubygems'
require 'bundler/setup'
require 'nokogiri'
require 'rest-client'
#require all your gems like normal
def parse(site)
Nokogiri::HTML(RestClient.get(site))
end
And for the gem file:
source: "https://rubygems.org"
gem 'nokogiri', '~> 1.6.7.2' #<= you can specify which version
gem 'rest-client' #<= you don't have to specify a version though
After you've got everything set up, cd to the directory that has the gemfile and run bundle install this will install all the gems
I'm developing a gem, and I need to load that gem's code into irb for testing purposes without building/publishing the gem and then installing it onto my system the traditional way via gem install <gem's name>.
To illustrate:
$ pwd
Users/me/development/gem_name/
$ irb
2.2.2 :001 > require 'gem_name'
=> true
The problem is that irb isn't loading the gem's code from my working dir because I added a method to the gem in the working dir and it's not available in the version of the gem that irb loaded above.
How can I load the version of the gem that is in the dir that I'm currently working in (i.e. the gem's dir)?
You could use require_relative to manually load the source code of your gem, for example require_relative './lib/gem_name/gem_name' assuming you have a file located at ./lib/gem_name/gem_name.rb that loads your gem. This guarantees that it is the version you have in your source code.
I created a simple gem by doing:
testgem.gemspec
Gem::Specification.new do |s|
s.name = 'testgem'
s.version = '0.0.1'
s.summary = "code generation"
s.authors = ['asdf']
end
created the following file layout:
testgem.gemspec
Gemfile
lib/
lib/testgem.rb
lib/testgem/other.rb
ran the following:
gem build testgem.gemspec
WARNING: no description specified
WARNING: no email specified
WARNING: no homepage specified
Successfully built RubyGem
Name: testgem
Version: 0.0.1
File: testgem-0.0.1.gem
installed it:
gem install ./testgem-0.0.1.gem
Successfully installed testgem-0.0.1
1 gem installed
tested to see if irb can see it:
irb
require 'testgem'
oadError: cannot load such file -- testgem
I'm using Ruby 1.9.3-p194
It seems to be installed if I do:
gem list
..
testgem (0.0.1)
..
What could be the issue?
You need to add your lib to the search path. Just add
$:.push File.expand_path("../lib", __FILE__)
on top of your .gemspec
When you use require in Ruby, you are trying to load a file, not a gem. The file could of course be contained in a gem, and by convention a gem will have a file with the same name as the gem itself so that if you wanted to use the gem foo you would use require 'foo'. This isn’t always the case though, for example to use the bcrypt-ruby gem you need to require 'bcrypt'.
Additionally a gem doesn’t necessarily have to contain any filles at all. An example of this is the rails gem, which doesn’t contain any files itself (at least in version 3.2), but has dependencies to the various Rails components, so that you can install them all in one step.
In your case, although you have a lib/testgem.rb file in your gems project directory, you are not including it in your gem. You need to specify which files should be included, the default is to not include anything.
To simply include all the files in your project directory, you can add something like:
s.files = Dir.glob '**/*'
to your gemspec.
You need to require 'rubygems' first.
I've got a wrapper for my Gem, socks, inside socks.rb. The entire file is made up of require statements, and a module declaration:
# lib/socks.rb
require 'socks/version'
require 'socks/base_controller'
require 'socks/templates'
require 'socks/tasks'
require 'socks/rake_tasks'
module Socks
end
However, require 'socks/tasks' and socks/rake_tasks is giving me a LoadError: no such file to load -- socks/tasks / rake_tasks error.
Is this a problem with the alignment of the require statements, or just the code?
Code is on Github: https://github.com/Beakr/socks
EDIT: require './socks/tasks' is now working, however require './socks/rake_tasks' is not.
Ruby load files using its $LOAD_PATH. This global array is changed by e.g. rubygems and bundler to allow to find libraries in various locations. In your sock.gemspec you have defined
gem.require_paths = ["lib"]
which means that rubygems will add the lib directory of your gem to ruby's $LOAD_PATH. But it odes so only if you have installed the gem and the gemspec is thus evaluated. If you don't want to install your gem, you can test your gem using
bundle exec irb
in your gem directory, or alternatively by first adapting your $LOAD_PATH in your irb session like so:
$LOAD_PATH.push "/path/to/your/gem/lib"
require 'socks'
I'm trying to use rake in my ruby script...(Ruby 1.8.6, JRuby 1.6.5)
Downloaded rake using gem install --remote rake, looks ok on install...
Fetching: rake-0.9.2.2.gem (100%)
Successfully installed rake-0.9.2.2
1 gem installed
I've got a simple ruby script which works fine, but when I import rake to using any of the following requires, it starts complaining....
require 'rake'
LoadError: no such file to load -- rake
or
require '/lib/rake'
LoadError: no such file to load -- lib/rake
After some searching, I found that adding require 'rubygems' just before rakefixes the issue....
require 'rubygems'
require 'rake'
Even though it's working, I've got some questions...
The gem spec on rake shows the require_path as lib, so why
doesn't require '/lib/rake' work? Am I misunderstanding the significance of require_path?
Why is it necessary to place require 'rubygems' before require
'rake'
Yes, you are misunderstanding the significance. The require_paths in the specification is an array of subdirectories of that gem's installation directory that should be searched for files belonging to the gem.
To find out where rake really is, try this:
$ gem which rake
You'll see that it is actually installed somewhere completely unrelated to /lib; on my system, it's under /var/lib/gems. Ruby gems, in general, live in their own directory structure; the only file in the standard Ruby include path ($:) is rubygems itself, which you used to have to explicitly require in order to make any actual gems visible. (Since Ruby 1.9, that has not been necessary.)
Gems are more complex than just libraries to load; you can have multiple versions of the same gem installed, and specify which one you want at a time, and do other things that wouldn't work if the gems were just dumped into the standard Ruby include path.
The require_path in the gemspec tells ruby where the files of this gem are located within the gem. It makes you able to type require 'rake', and ruby then knows it needs to look for /lib/rake within the gem installation folder.
In Ruby 1.8, rubygems (the mechanism responsible for making gems available to your app) is not loaded by default, and the default ruby isn't aware of any gem on your system. You need to load rubygems before being able to require any other gem. This is not the case anymore with Ruby 1.9.