module Jekyll::External

Public Class Methods

blessed_gems() click to toggle source

Gems that, if installed, should be loaded. Usually contain subcommands.

# File lib/jekyll/external.rb, line 10
def blessed_gems
  %w(
    jekyll-compose
    jekyll-docs
    jekyll-import
  )
end
require_if_present(names) { |name, version_constraint(name)| ... } click to toggle source

Require a gem or file if it’s present, otherwise silently fail.

names - a string gem name or array of gem names

# File lib/jekyll/external.rb, line 23
def require_if_present(names)
  Array(names).each do |name|
    require name
  rescue LoadError
    Jekyll.logger.debug "Couldn't load #{name}. Skipping."
    yield(name, version_constraint(name)) if block_given?
    false
  end
end
require_with_graceful_fail(names) click to toggle source

Require a gem or gems. If it’s not present, show a very nice error message that explains everything and is much more helpful than the normal LoadError.

names - a string gem name or array of gem names

# File lib/jekyll/external.rb, line 54
      def require_with_graceful_fail(names)
        Array(names).each do |name|
          Jekyll.logger.debug "Requiring:", name.to_s
          require name
        rescue LoadError => e
          Jekyll.logger.error "Dependency Error:", <<~MSG
            Yikes! It looks like you don't have #{name} or one of its dependencies installed.
            In order to use Jekyll as currently configured, you'll need to install this gem.

            If you've run Jekyll with `bundle exec`, ensure that you have included the #{name}
            gem in your Gemfile as well.

            The full error message from Ruby is: '#{e.message}'

            If you run into trouble, you can find helpful resources at https://jekyllrb.com/help/!
          MSG
          raise Jekyll::Errors::MissingDependencyException, name
        end
      end
version_constraint(gem_name) click to toggle source

The version constraint required to activate a given gem. Usually the gem version requirement is “> 0,” because any version will do. In the case of jekyll-docs, however, we require the exact same version as Jekyll.

Returns a String version constraint in a parseable form for RubyGems.

# File lib/jekyll/external.rb, line 41
def version_constraint(gem_name)
  return "= #{Jekyll::VERSION}" if gem_name.to_s.eql?("jekyll-docs")

  "> 0"
end