module Kernel
# REFACTOR: This should be pulled out into some kind of hacks file.
remove_method :gem if 'method' == defined? gem # from gem_prelude.rb on 1.9
##
# Use Kernel#gem to activate a specific version of +gem_name+.
#
# +requirements+ is a list of version requirements that the
# specified gem must match, most commonly "= example.version.number". See
# Gem::Requirement for how to specify a version requirement.
#
# If you will be activating the latest version of a gem, there is no need to
# call Kernel#gem, Kernel#require will do the right thing for you.
#
# Kernel#gem returns true if the gem was activated, otherwise false. If the
# gem could not be found, didn't match the version requirements, or a
# different version was already activated, an exception will be raised.
#
# Kernel#gem should be called *before* any require statements (otherwise
# RubyGems may load a conflicting library version).
#
# In older RubyGems versions, the environment variable GEM_SKIP could be
# used to skip activation of specified gems, for example to test out changes
# that haven't been installed yet. Now RubyGems defers to -I and the
# RUBYLIB environment variable to skip activation of a gem.
#
# Example:
#
# GEM_SKIP=libA:libB ruby -I../libA -I../libB ./mycode.rb
def gem(gem_name, *requirements) # :doc:
skip_list = (ENV['GEM_SKIP'] || "").split(/:/)
raise Gem::LoadError, "skipping #{gem_name}" if skip_list.include? gem_name
if gem_name.kind_of? Gem::Dependency
unless Gem::Deprecate.skip
warn "#{Gem.location_of_caller.join ':'}:Warning: Kernel.gem no longer "\
"accepts a Gem::Dependency object, please pass the name "\
"and requirements directly"
end
requirements = gem_name.requirement
gem_name = gem_name.name
end
spec = Gem::Dependency.new(gem_name, *requirements).to_spec
spec.activate if spec
end
private :gem
end
