There is similar question here.
Ruby: Rails: Which version of a gem is used?
But it's about when Gemfile is used.
I want to know if there is no Gemfile, which version of gem is used.
For example I have 4 versions of selenium-webdriver in my system.
% gem list | grep selenium
selenium-webdriver (2.53.0, 2.48.1, 2.46.2, 2.45.0)
And I just use it by pry and require 'selenium-webdriver. How can I know which version is used? Only the latest is selected?
You probably have more than one gem because each project with Gemfile in your machine have one different version of it.
When using the gem via require or command line without specifying the version the last one - the greater version - will be automatically used.
By convention, in the most part of the cases, you can print the version doing the following:
require 'some_gem'
puts SomeGem::VERSION
# => "3.0.3"
Related
If I have a local gem (gemfile.gem) how can I get the name and version information from code or the command line without installing the gem.
Reason: I'm installing a user gem to validate it and want to uninstall it to clean up. User gem is not something I control so I can't depend on naming conventions.
CLI Solution:
gem spec gemfile.gem name
gem spec gemfile.gem version
Ruby Solution:
name = Psych.safe_load(`gem spec gemfile.gem name`).to_s
version = Psych.safe_load(`gem spec gemfile.gem version`, permitted_classes: [Gem::Version]).to_s
# Now you can uninstall the gem with
Gem::Uninstaller.new(name, {:version => version, :force => true}).uninstall
You can see locked version in Gemfile.lock
cat Gemfile.lock | grep gem-name
Other option, but need bundle install first
bundle exec gem dependency | grep gem-name
Update:
If you need to check local gem version, for example some-gem.gem, you can use such command to parse all information from binary
gem specification some-gem.gem
or just
gem spec some-gem.gem
You can also look it with Ruby format
gem spec some-gem.gem --ruby
Of course you can use grep to filter lines with version word
But it's better to pass it as argument like this
gem spec some-gem.gem version
Your question is ambiguous. If you mean "How can I read in the gem name and version from the gemspec?" then you can use the output of Gem::Specification#load. For example, assuming you have a gem with a standard layout and foo_bar.gemspec in the root of your gem's project directory, you can use Git to find the top-level of your project and read in the gemspec:
$ cd "$(git rev-parse --show-toplevel)
$ ruby -e 'puts Gem::Specification.load "#{File.basename Dir.pwd}.gemspec"'
#<Gem::Specification name=foo_bar version=0.1.0>
You can then parse the output with sed, awk, or cut.
A Gemfile does not (necessarily) specify an exact version of a dependency. It might specify nothing (i.e. "any version is fine"), or ~> 1.0 (i.e. >= 1.0 and < 2.0), or whatever. Also, dependency constraints might further restrict the valid range of versions.
I'm assuming that this isn't what you meant by your question. Instead, you'd like to know what exact versions of dependencies will be installed by running bundle install, given a Gemfile.lock.
One way to achieve this reliably (i.e. rather than using grep and eyeballing which line(s) are most relevant) is by parsing the Gemfile.lock:
require 'bundler'
lockfile = Bundler::LockfileParser.new(Bundler.read_file('Gemfile.lock'))
puts lockfile.specs.find { |spec| spec.name == 'the-gem-you-want-to-check' }.version
I'm just trying to use the simple career_builder gem and just get it imported by running the simple script:
require 'career_builder'
puts 'Hello world!'
and yet get the following error: /Library/Ruby/Site/2.0.0/rubygems/dependency.rb:315:in 'to_specs': Could not find 'activesupport' (~> 2.3.5) - did find: [activesupport-4.2.1,activesupport-3.1.12,activesupport-3.0.3] (Gem::LoadError)
I installed the gem with gem install career_builder and ran bundle install and even updated activesupport to the most recent version, but for some reason, the program can't find the newer version of activesupport. Does the gem require version 2.3.5?
http://guides.rubygems.org/patterns/
The ~>or 'twiddle-waka' is a ruby gems shortcut to specify the earliest version of the gem you can use without letting you go up to the next major release.
Your gem is being a bit unorthodox and also specifying a patch level.
So the gem_specification you're working with (activesupport' (~> 2.3.5)) really means minimum version of 2.3.5 maximum of the last patch released before 2.4.0.
The activesupport versions you have installed are all for subsequent major releases and won't work. Install something between 2.3.5 and 2.4.0 and you should be good to go.
Yes. It does require Active Support version >= 2.3.5 and < 2.4.0. All of your Active Support versions are > 2.4.0.
~> is called the spermy operator. See Meaning of tilde-greater-than (~>) in version requirement?
The gem has not been updated in 4 years, so it uses Rails 2.
FWIW, I don't think you'll have much luck getting it to work, so you may want to find a similar gem that works with Rails 4 and has been updated within the last few months.
I think I have a basic understanding of what require/include statements at the top of a ruby script are doing, like
require 'rspec'
These statements are easy to google and find relevant results. But sometimes I have seen a gem statement like
gem 'rspec'
What does this line do?
In ruby code, gem(gem_name, *requirements) defined in Kernel tells Ruby to load a specific version of gem_name. That's useful when you have installed more than one version of the same gem.
For example, if you have installed two versions of rspec, say 2.12.0 and 2.13.0, you can call gem before require to use specific version. Note that gem should come before the require call.
gem 'rspec', '=2.12.0'
require 'rspec'
A gem 'gem_name' without version uses the latest version on your machine, and that's unnecessary. You can call require without gem to get the same behavior.
And besides, in Bundler::Dsl, gem is used to tell bundler to prepare/install specific version of ruby gems. You'll see that in Gemfile
The original behaviour of require, before Rubygems, was to search all the directories listed in the $LOAD_FILES variable for the file, and to load the first one it finds that matches. If no matching file was found, require would raise a LoadError.
Rubygems changes this process. With Rubygems, require will search the existing $LOAD_PATH as before, but if there is no matching file found then Rubygems will search the installed gems on your machine for a match. If a gem is found that contains a matching file, that gem is activated, and then the $LOAD_PATH search is repeated. The main effect of activating a gem is that the gems lib directory is added to your load path. In this way the second search of the load path will find the file being required.
Normally this will mean that the latest version of a gem that you have installed gets activated. Sometimes you will want to use a different version of a gem, and to do that you can use the gem method. The gem method activates a gem, and you can specify the version you want, but doesn’t require any files. When you later require the files you want, you’ll get them from the gem version you specified.
In Ruby, gems are packages with functionality that can be used out of the box (as libraries in other Programming languages).
The gems that you use with your Ruby Project can easily be managed with a tool called "bundler", just google it. The snippet of code you posted is part of the spec file that bundler uses to install and update all the libraries that you specify for your project.
If you are developing a Ruby on Rails, using gems an managing them with bundler is very common and so to say best practice.
Gems are just great because there are so many useful libraries that extend default functionality, eg of rails, and that you can use out of the box!
For a list of gems, visit rubygems.org
I have seen many
You have already activated rake 0.9.x, but your Gemfile requires rake 0.x.x
errors.
Of course, they can be solved (temporarily or always) by some methods like the following.
bundle exec rake
The method above works but you always have to type bundle exec.
It can also be solved by
bundle update
But bundle update also updates your other gems.
Some say it can be solved by
gem uninstall unwanted_rake_version
Yes, the unwanted rake can be installed but it is still marked as activated thus, still giving the error.
One solution would be to explicitly specify the rake version in your Gemfile but, that is not the question. It is on how to set the default rake version, or activate that specific version in rvm or other types of ruby installations?
The newer versions of rake can be activated by supplying an optional first argument, that is the gem version.
$ rake 0.9.2
Alternatively, if you have an older version of rake you can update the rake script manually to include this parameter (or specify any specific version you want).
The rake script usually lives in /usr/bin/rake (or ~/.rvm/gems/ruby-#{ruby-name}/rake if using rvm). And dictates the version of them gem to load before parsing paramaters.
It looks like this on my system.
$ cat ~/.rvm/gems/ruby-1.9.2-p180/bin/rake
#!/home/tomcat/.rvm/rubies/ruby-1.9.2-p180/bin/ruby
#
# This file was generated by RubyGems.
#
# The application 'rake' is installed as part of a gem, and
# this file is here to facilitate running it.
#
require 'rubygems'
version = ">= 0"
if ARGV.first =~ /^_(.*)_$/ and Gem::Version.correct? $1 then
version = $1
ARGV.shift
end
gem 'rake', version
load Gem.bin_path('rake', 'rake', version)
The important bit is gem 'rake', version changing version will force rake to a specific version system/rvm wide.
For more info, Katz' article explains nicely how binaries run under rubygems
When I get that error, its usually a result of working between projects that depend on different versions of rake. An easy fix is
gem uninstall rake
And then in your project directory (assuming you're working with Bundler) simply
bundle
I always uninstall rake first, command like this:
gem uninstall rake -v=version
then install another version
gem install rake -v=version
Is it possible to add a gem dependency only if the person is using a certain version of ruby?
Background: I'm working on a fork of a project that uses Test::Unit::Autorunner and the like. They are part of the standard library in ruby 1.8, but aren't part of the standard library in 1.9.1, and is instead in the "test-unit" gem. I want to add a dependency that says that if someone's using ruby 1.9.1 or later, install the "test-unit" gem, but if they're using 1.8 or earlier, they don't need to install anything.
If you look at the gemspec documentation for add_dependency, there isn't an option for a ruby version. Perhaps you could use the post_install_message attribute to tell the user to install the gem if they're using ruby 1.9.
I did this exact thing for a project. The trick is to add the script as an extension, which will then get executed at install time on the user's machine.
Here are code snippets and links to our github:
First, when in the gemspec (we're actually using a Rakefile to generate it, but the result ends up the same) source
# This file *needs* to be named this, there are other files
# for other extension processors
s.extensions << 'ext/mkrf_conf.rb'
And then the relevant lines in that mkrf_conf.rb source
require 'rubygems/dependency_installer.rb'
inst = Gem::DependencyInstaller.new
inst.install "test-unit" if RUBY_VERSION > "1.9"
Gem doesn't support conditional dependencies (except on gem builder's environment -as noted above), and bundler is not a viable option to solve this either - see https://github.com/carlhuda/bundler/issues/1281
hay ... i'm kind of a ruby newbie ... if this is the best way to do it.
any way ... i wish i can do that using only Ruby .... though u can use your operating system shell to do that, by using this in your program installer, just execute (works for Linux based operating systems):
$ruby --version
(u can execute that from a ruby installer file, just like: ruby --version)
and put a possibility according to output, if it's 1.9.1 add an extra line to execute:
$ sudo gem install gem_name
else, just leave it be.
Checkout this tutorial in the Ruby Programming wikibook.
Tt shows how to install different versions of dependencies depending on what version of ruby the installee is using.
(short answer--it ain't as easy as it should be)
You can't. You need to build two gems, one with
spec.required_ruby_version = '~> 1.8.6'
and one with
spec.required_ruby_version = '~> 1.9.1'
spec.add_dependency 'test-unit', '~> 2.0.5'
Gemspecs are just ruby files anyway, so you can execute any ruby code inside them, so:
spec.add_dependency = 'test-unit', '>= 2.0' if RUBY_VERSION =~ '1.9'
EDIT: Specs run only on the builders machine.