stdlib_libraries/build_settings.rb

tests/_examples/stdlib_libraries/build_settings.rb in the metorex repository.

require 'rbconfig'
require 'rbconfig/sizeof'
require 'resolv'
require 'optparse'

# What the interpreter was built as, all of it named with strings.
p(RbConfig::CONFIG.values_at("MAJOR", "MINOR", "TEENY") == RUBY_VERSION.split("."))
p(RbConfig::CONFIG["PATCHLEVEL"] == RUBY_PATCHLEVEL.to_s)
p(RUBY_PLATFORM.include?(RbConfig::CONFIG["host_cpu"]))
p(RUBY_DESCRIPTION.include?(RUBY_VERSION))
p(RbConfig::TOPDIR)
p(RbConfig::SIZEOF["void*"] * 8)
p([RbConfig::SIZEOF["float"], RbConfig::SIZEOF["double"]])
p(RbConfig::LIMITS["FIXNUM_MAX"] > 0)
p([RbConfig::LIMITS["SHRT_MIN"], RbConfig::LIMITS["SHRT_MAX"]])

# A name and an address, read out of a hosts file.
hosts = Resolv::Hosts.new(File.join(__dir__, "hosts_fixture"))
resolver = Resolv.new([hosts])
p(resolver.getaddress("localhost"))
p(resolver.getnames("127.0.0.1").include?("localhost"))
p(resolver.getaddresses("billing"))
begin
  Resolv.new([]).getaddress("nothing.answers.to.this.")
rescue Resolv::ResolvError => problem
  p(problem.class)
end

# Options read against a description of what they mean.
settings = {}
parser = OptionParser.new do |options|
  options.on("-v", "--[no-]verbose", "Run verbosely")
  options.on("-r", "--require LIBRARY", "Require LIBRARY first")
end
rest = parser.parse(%w[--verbose --require optparse leftover], into: settings)
p(settings)
p(rest)
p(parser.parse(%w[--no-verbose], into: {}) && settings[:verbose])

Output:

true
true
true
true
nil
64
[4, 8]
true
[-32768, 32767]
"::1"
true
["10.0.0.5"]
Resolv::ResolvError
{verbose: true, require: "optparse"}
["leftover"]
true