Duck typing is another way to do polymorphism. Actually, duck typing is polymorphic by definition. Duck typing describes the concept of creating objects of arbitrary types that all respond to the same method call: if it quacks like a duck, walks like a duck, then it’s probably a duck.
The only thing we do care is whether unrelated objects have a common particular behavior (method).
Imagine a website.rb program that have different element that can respond to a mouse click.
# website.rb
class Checkbox
def click
# check/uncheck
end
end
class Textbox
def click
# focus
end
end
class RadioButton
def click
# select current option, unselect other
end
end
class Link
def click
# open link
end
end
From the point of view of a possible mouse or pointer object, the object does not need to know if the element is a checkbox, a link or something else. All elements have the ability to handle a click whether they are a checkbox, link or else.
Like the idiom say, we don’t need to check whether it is a duck. It’s good enough to know it quacks like a duck and walks like a duck ; as long as it behaves like a duck, it’s as good as a real duck.