Override default raise behavior

example.rb

class MyStandardError < StandardError; end

module Kernel
  alias_method :__raise__, :raise

  def raise(*args)
    return __raise__(MyStandardError) if args.empty?
    __raise__(*args)
  end
end

class Example
  def without_args
    raise
  end

  def with_args
    raise RuntimeError, "Hello World"
  end
end

# Example.new.with_args       #=> RuntimeError: Hello World
# Example.new.without_args    #=> MyStandardError: MyStandardError