module Bootsnap::ExplicitRequire

def self.from_archdir(feature) 

def self.from_archdir(feature)
  require(File.join(ARCHDIR, "#{feature}.#{DLEXT}"))
end

def self.from_rubylibdir(feature) 

def self.from_rubylibdir(feature)
  require(File.join(RUBYLIBDIR, "#{feature}.rb"))
end

def self.from_self(feature) 

def self.from_self(feature)
  require_relative "../#{feature}"
end

def self.with_gems(*gems)

depends on, without forcing full LOAD_PATH traversals.
This is useful before bootsnap is fully-initialized to load gems that it

temporarily remove all gems not listed in this call from the LOAD_PATH.
only core ruby source paths and these gems -- that is, roughly,
Given a set of gems, run a block with the LOAD_PATH narrowed to include 
def self.with_gems(*gems)
  orig = $LOAD_PATH.dup
  $LOAD_PATH.clear
  gems.each do |gem|
    pat = %r{
      /
      (gems|extensions/[^/]+/[^/]+)          # "gems" or "extensions/x64_64-darwin16/2.3.0"
      /
      #{Regexp.escape(gem)}-(\h{12}|(\d+\.)) # msgpack-1.2.3 or msgpack-1234567890ab
    }x
    $LOAD_PATH.concat(orig.grep(pat))
  end
  $LOAD_PATH << ARCHDIR
  $LOAD_PATH << RUBYLIBDIR
  yield
ensure
  $LOAD_PATH.replace(orig)
end