You can use $this->router->fetch_class()
to get the current controller and $this->router->fetch_method()
to get the method too if needed.
So similar to the Yii example you linked to, you could do something like
$is_home = $this->router->fetch_class() === 'name_of_home_controller' ? true : false;
Or to match method too
$is_home = ($this->router->fetch_class() === 'name_of_home_controller' && $this->router->fetch_method() === 'name_of_home_method') ? true : false;
This way even if the page url is http://yoursite.com/ (assuming the home controller+method is the default), http://yoursite.com/home_controller/, http://yoursite.com/something/that/routes/to/home/controller/, etc, as long as it's calling that controller, it'll set $is_home to true.
Edit: Also you can use ($this->router->fetch_class() === $this->router->default_controller)
if you don't want to explicitly state the home controller and it's set to the default controller.
Update for CI v3:
$this->router->fetch_class()
and $this->router->fetch_method()
were deprecated in CI v3. Use $this->router->class
and $this->router->method
instead.