I'm trying to require the new (i.e. not the one bundled with ruby) version of test/unit. As per the instructions I installed it with gem i test-unit. But now when I require test/unit I seem to be requiring the old version. For example, I don't have the method Test::Unit.at_start. This happens even when I explicitly require the full path to the new test/unit installation.
Is there any way for me to investigate which symbols are being loaded and why?
Since Ruby comes with an implementation of test/unit (it’s actually a Minitest compatibility wrapper) calling require 'test/unit' will load that version, since it is already on the load path. Calling require '/absolute/path/to/test/unit' will load the new file, but when that file calls e.g. require 'test/unit/testcase it will load the files from stdlib, resulting in a mix of classes (so don’t do that).
What you need to do is activate the gem with the gem method before you require it. That will ensure the gem lib path is on your load path before the stdlib, so require will find those files first.
gem 'test-unit' # You can also pass a specific version as a second
# argument to `gem` if you want.
require 'test/unit' # This will find the gem version.
# Now the gem version will be loaded.
Related
If I understand correctly puting
require 'rubygems'
require 'bundler/setup'
at the top of my ruby source file will ensure that subsequent requires will load the versions of the gems specified in the Gemfile located in the same directory, thus allowing me to develop multiple projects which use different versions of the same gem - is this correct? How is this different from using Bundler.setup()?
When you require 'bundler/setup' it loads this file which calls Bundler.setup for you. This means there's no need for you to include that in your own code.
RubyGems is loaded implicitly by Ruby, unless you're using a really old version, so require 'rubygems' isn't needed.
I am working on learning Ruby and one thing that I have seen in several instances and cannot understand are scripts that start with the keyword gem.
An example can been seen in the Sensu code.
gem "amqp", "1.3.0"
require "amqp"
require File.join(File.dirname(__FILE__), "base")
I understand the require statement for accessing another gem, but what does the exact gem "amqp", "1.3.0" mean?
This is the gem method that Rubygems adds to Kernel (Rubygems is required by default in current Ruby versions). It activates a specific version of a gem (version 1.3.0 of the amqp gem in this case), meaning that the gems lib dir (or whatever dirs the gem specifies) is added to your LOAD_PATH, as are the lib dirs of any dependent gems it has.
It also checks that there are no version incompatibilities with any already activated gems.
All gems are activated when you use them. This normally happens when you call require. Calling gem activates the gem but doesn’t require any files from it, hence the line require "amqp" below (note the difference between amqp the gem, which the gem method refers to, and amqp the file, which is contained in the amqp gem and is what the require method is refering to).
This method is used to ensure you are using a specific version of a gem, without needing to use Bundler (or something similar). Bundler also has a gem method used in Gemfiles, but this is a different (but similar) method.
It’s also used to specify that you want to use the gem version of a library that is also part of the standard library (say if you want to use a more recent version). For example the Yaml library distributed with Ruby is Psych which is also available as a gem.
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 just wanted to understand for my self.
I'm using the nokogiri gem (for parsing HTML). If I got it right to open URLs I need to use a method from the gem 'open-uri'.
But when I include it in my Gemfile (on Windows developer's machine):
gem 'open-uri' - there is an error while bundle install that it can not find gem.
So If I use require 'open-uri' - its working.
So can some explain what is going on?
You're using bundler for your gem dependecies and you're doing it right but OpenUri is part of the Ruby standard library. That's why you only need to require it if you want to use it in your code.
require is used to load another file and execute all its statements. This serves to import all class and method definitions in the file. require also keeps track of which files have been previously required so it doesn't execute it twice.
A RubyGem is a software package, commonly called a “gem”. Gems contain a packaged Ruby application or library. The RubyGems software itself allows you to easily download, install, and manipulate gems on your system.
- What is a Gem?:
The Gemfile is then used by bundler to install the specified gems.
open-uri is not a gem but part of the Ruby Standard Library so it just needs to be required.
I have seen many samples of Ruby code with this line (for example, http://www.sinatrarb.com/). What is purpose of this require?
# require 'rubygems'
require 'sinatra'
get '/hi' do
"Hello world!"
end
In all cases the code works without this line.
require 'rubygems' will adjust the Ruby loadpath allowing you to successfully require the gems you installed through rubygems, without getting a LoadError: no such file to load -- sinatra.
From the rubygems-1.3.6 documentation:
When RubyGems is required, Kernel#require is replaced with our own
which is capable of loading gems on demand.
When you call require 'x', this is what happens:
If the file can be loaded from the existing Ruby loadpath, it
is.
Otherwise, installed gems are searched for a file that
matches. If it's found in gem 'y', that gem is activated
(added to the loadpath).
The normal require functionality of returning false if that file
has already been loaded is preserved.
See the documentation for Kernel#require to understand why this is necessary.
It is often superfluous. It will allow you to require specific versions of particular gems though, with the gem command.
https://guides.rubygems.org/patterns/#requiring-rubygems
As an addition to prior (and correct answers): Ruby 1.9 and newer ship with RubyGems built-in, so there is no real need to require 'rubygems'. Source here