class Bundler::Dsl

def gem(name, *args)
  if name.is_a?(Symbol)
    raise GemfileError, %{You need to specify gem names as Strings. Use 'gem "#{name.to_s}"' instead.}
  end
  options = Hash === args.last ? args.pop.dup : {}
  version = args
  _normalize_options(name, version, options)
  dep = Dependency.new(name, version, options)
  # if there's already a dependency with this name we try to prefer one
  if current = @dependencies.find { |d| d.name == dep.name }
    if current.requirement != dep.requirement
      if current.type == :development
        @dependencies.delete current
      elsif dep.type == :development
        return
      else
        raise GemfileError, "You cannot specify the same gem twice with different version requirements.\n" \
                        "You specified: #{current.name} (#{current.requirement}) and #{dep.name} (#{dep.requirement})"
      end
    else
      Bundler.ui.warn "Your Gemfile lists the gem #{current.name} (#{current.requirement}) more than once.\n" \
                      "You should probably keep only one of them.\n" \
                      "While it's not a problem now, it could cause errors if you change the version of just one of them later."
    end
    if current.source != dep.source
      if current.type == :development
        @dependencies.delete current
      elsif dep.type == :development
        return
      else
        raise GemfileError, "You cannot specify the same gem twice coming from different sources.\n" \
                        "You specified that #{dep.name} (#{dep.requirement}) should come from " \
                        "#{current.source || 'an unspecified source'} and #{dep.source}\n"
      end
    end
  end
  @dependencies << dep
end