RubyGems monkey-patches Kernel. This works "natively" because Ruby has come with RubyGems by default since version 1. Although this works natively, it is also important to know this difference when debugging. A gem is a bunch of related code used to solve a specific problem. Install a gem and get information about the gem environment as follows:. How does RubyGems solve this problem?
It monkey patches the Kernel 's require system with its own require method. With this in-place, when require honeybadger is called, it searches through the gems folder for honeybadger. For example, require 'honeybadger' produces something similar to the following:. At this layer, Bundler helps us easily specify all our project dependencies and optionally specify a version for each. Then, it resolves our gems, as well as installs it and its dependencies. Building real-world applications pre-bundler came with a myriad of challenges, such as the following:.
Bundler solves all three problems and gives us a sane way to manage our app dependencies by doing the following. From the above, the bundler generates the version of httparty to be installed, as well as its own dependencies in the Gemfile. This file is the blueprint of our app dependencies and should be checked into version control. It ensures that our project dependencies are consistent across environments development, staging, or production. It resolves the dependencies for httparty by finding a suitable version for its dependencies and specifying them.
Bundler also tries to resolve dependencies between gems. For example,. This is because two gems have dependencies that are not compatible and cannot be automatically resolved. When you run rspec in a project directory, there is a possibility of running a different version other than what was specified in the Gemfile. This is because the most recent version will be selected to run versus the version specified in the Gemfile.
Often, we read articles where we run commands like. Binstubs are wrappers around Ruby executables to ease the usage of bundle exec. To generate a binstub run, use bundle binstubs gem-name. This creates a binstub in the. Honeybadger has your back when it counts. We're the only error tracker that combines exception monitoring, uptime monitoring, and cron monitoring into a single, simple to use platform.
The final step is to run rbend rehash so the shim binaries get rebuilt. Now lets download and install the release candidate and then have a look at how we can switch between the two versions with rbenv :. Run configure and make as before.
Again we need to be careful with the --prefix path. This time it should point to the RC:. So, if without support library my app size was 1MB, then now with support library the size is 2MB extra, which means 3MB total. Thus, the best option is to have that 2MB support library already in your OS for any number of apps, instead of having it for each application.
So, support libraries are meant to be used when you really want some efficient features in your app to support older versions.
The answer is that there could be a lot of errors. Suppose some user doesn't have that update support library installed There is also the chance that as an update, it may not work as efficient as supposed to be, or may cause problems while integrating with the OS, as we already seen that each OS windows, Linux, mac comes with new versions, instead of just giving updates for life time for all new features.
Suppose you have rails 3. This will create the Gemfile for you, locked to the version of rails you specified on the command-line. I deliberately omitted the idea of keeping a separate copy of gems for the new project, because that goes against the Bundler philosophy, which is to have all gems installed in one place.
When you run rails, Bundler will pick the correct gem versions automatically from that central location. That means a project can share gems instead of installing a fresh copy for itself.
Note, however that each version of ruby you install will have its own gems. This is a good thing because native extensions likely won't work across ruby versions.
You do have to be a bit more aware, because most commands, like rake , will load the newest version of rake that you have installed. You'll need to run bundle exec rake Usually I'll run bundle exec for all commands except rails. You can create an alias to make it shorter I use bex.
To automate this with gem executables, you can use rbenv-binstubs, but you still have to be aware that running non-gem executables like ruby and irb won't automatically use the Gemfile.
Sidenote : rails new will run bundle install , which will check for the newest version of the dependencies. If you want bundler to try to use currently installed gems that satisfy the dependency requirements, you can skip the bundle install with rails new --skip-bundle , then run bundle check in the app dir. Sidenote 2 : suppose you want to use a ruby version for Project2 e. In that case, running gem install as specified above will install the gems under 2. To solve that problem, you can force the commands to use the preferred version via environment variable:.
You could use rbenv shell to set the variable, but I only recommend that if you don't want rbenv to auto-switch based on. It's very easy to forget that you have the variable set, and when you cd to a different project, it won't be using the version you expect. If you want to continuously i.
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