ruby import from

imports.rb

module Imports
  refine(Object) do
    def from(mod, &block)
      imports = []
      if block
        RubyVM::AbstractSyntaxTree.of(block).children[2].children.each do |node|
          case node.type
          when :VCALL
            imports << node.children[0]
          when :DASGN_CURR
            node.children in [name, subnode]
            imports << [subnode.children[0], name]
          end
        end
      else
        imports = mod.methods false
      end
      Module.new do
        refine(Object) do
          imports.each do |name, as = name|
            begin
              define_method as, &mod.method(name)
            rescue
              const = mod.const_get(name)
              define_method(as) { const }
            end
          end
        end
      end
    end
  end
end

main_class = self.singleton_class
Imports.module_eval do
  refine(main_class) do
    alias import using
  end
end

imports_sample.rb

require_relative './imports'
using Imports

import from(Math) { sin; cos; tan }
p cos(3.1415926535 / 3) #=> 0.5
p sin(3.1415926535 / 3) #=> 0.866

import from(Math) { cos = sin; sin = cos; pi = PI; log = log10 }

p cos(pi / 3) #=> 0.866
p sin(pi / 3) #=> 0.5
p log(100000) #=> 5

import from Math
p log2(8) #=> 3
p 4 * atan(1) #=> 3.14