how to make a string into an object instance name?

Nanyang Zhan wrote:

and i saw:
def link_to_page(page_name, web = @web, text = nil, options = {})

in a helper file.
what does "web = @web" do here?

It means if "web" is not passed in to the link_to_page method, it
defaults to the value of @web.

link_to_page(:page_name) #=> uses @web
link_to_page(:page_name, :my_web) #=> uses :my_web

Dan Manges