tap.rb

require 'pathname'
require 'pry'

class Object
  def tap(msg=nil, with:nil, to:nil, &block)
    if block_given? # original Object#tap functionality
      return super &block
    else
      if msg || with # msg to self e.g. #mkdir #gsub!
        if msg
          args = with || []
          self.send msg, *args
        else
          self.send with
        end
      elsif to # into method e.g. ::puts
        if to.is_a? Symbol
          method(to).call self
        else
          to.call self
        end
      else
        raise ArgumentError 'No `msg`, `with:`, `to:` provided.'
      end
    end

    self
  end
end

f = Pathname 'boof'
f.rmdir if f.exist?

puts 'Object#tap(&block) works'.tap {|str| puts str}

puts
puts 'Object#tap(to: method_sym) works'.tap to: :puts
puts 'Object#tap(to: method) works'.tap to: method(:puts)
puts 'Object#tap(to: proc) works'.tap to: ->(str) { puts str }

f.tap with: :mkdir
puts
2.times { puts "Object#tap(with:) works" } if f.exist?
# :D

puts
puts "Object#tap(method_sym, with: args_arr) doesn't work"
  .tap(:gsub!, with: [/doesn't/,''])
  .tap(:gsub!, with: [/ work/,'works'])
  .tap to: :puts

f.rmdir


# $ ruby tap.rb
#
# Object#tap(&block) works
# Object#tap(&block) works
#
# Object#tap(to: method_sym) works
# Object#tap(to: method_sym) works
# Object#tap(to: method) works
# Object#tap(to: method) works
# Object#tap(to: proc) works
# Object#tap(to: proc) works
#
# Object#tap(with:) works
# Object#tap(with:) works
#
# Object#tap(method_sym, with: args_arr) works
# Object#tap(method_sym, with: args_arr) works