Create a ruby object from a supertype object - ruby

Question

I am using the Selenium Webdriver libraries in Ruby. A typical piece of code looks like this:
require 'rubygems'
require 'selenium-webdriver'
driver = Selenium::WebDriver.for :firefox
# driver is an instance of Selenium::WebDriver::Driver
url = 'http://www.google.com/'
wait = Selenium::WebDriver::Wait.new(:timeout => 10)
driver.get(url)
wait.until { driver.title.start_with? "Google" }
I would like to create a subclass of Selenium::WebDriver::Driver called Selenium::WebDriver::Driver::MyClass that will contain some new methods and instance variables.
As the above code illustrates, the way that instances of Selenium::WebDriver::Driver are created is with Selenium::WebDriver.for.
Without wholesale copying of code, how can I create a version of Selenium::WebDriver.for that does the same thing as Selenium::WebDriver.for but creates instances of Selenium::WebDriver::Driver::MyClass?

Answer 1

Why not just override the Selenium::WebDriver.for ? let me show you that my an example
# selenium code
module Selenium
class WebDriver
def self.for
puts "creating oldclass"
end
end
end
# your code
class Selenium::WebDriver
def self.for
puts "creating myclass"
end
end
Selenium::WebDriver.for
output:
creating myclass
Safe alternative is to derive class from Selenium::WebDriver and use that in your code, or to the extreme you can just open Driver class and add your behavior to it.

Answer 2

Check the source code. Selenium::WebDriver.for simply delegate the method call to Selenium::WebDriver::Driver.for.
If you don't have listener attached, you can simple create your own bridge MyClass::Bridge.new and then pass that to Selenium::WebDriver::Driver.new.
If you insist override the for method, here is some code snippet that might help.
module Selenium
module WebDriver
class Driver
class << self
alias_method :old_for, :for
def for(browser, opts = {})
if browser == :myclass
# create your MyClass::Bridge instance and pass that to new()
else
old_for(browser, opts)
end
end
end
end
end
end

Answer 3

If you just want to define some extra methods on your driver, you do not need to override WebDriver.for.
The following worked well for me:
First, in file customdriver.rb
require 'selenium-webdriver'
class CustomDriver < Selenium::WebDriver::Driver
#a custom method..
def click_on (_id)
element = find_element :id => _id
element.click
end
#add other custom methods here
#....
end
Then, in file main.rb
require-relative 'customdriver'
driver = CustomDriver.for :chrome
driver.click_on("buttonID")
Regards,