Duck typing facts for kids

In computer programming, especially with object-oriented languages, duck typing is a simple way to check if a computer program can use an object. Instead of checking what "type" of object something is (like if it's a "Dog" object or a "Cat" object), you just check if it can do the actions you need it to do. If it can, then it's good enough!

This idea comes from a saying called the duck test. It was made popular by the poet James Whitcomb Riley:

When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.

This means if something acts like a duck, you can treat it like a duck, even if you don't know its exact "species." In programming, if an object can "walk," "swim," and "quack" (meaning it has the right methods or functions), then your program can use it like a "duck."

What is Duck Typing?

Duck typing is a way of thinking about how different parts of a computer program work together. Imagine you have a toy box. Instead of sorting toys by their exact type (like "car" or "truck"), you might sort them by what they can do. For example, all toys that can roll might go together.

In programming, duck typing means you don't care if an object is officially a "Car" or a "Bicycle." You only care if it has a `drive()` function. If it does, you can tell it to `drive()`.

The Duck Test Explained

The "duck test" is a simple way to understand this idea. Think about a bird. If you see a bird that:

• Walks like a duck
• Swims like a duck
• Quacks like a duck

Then, for all practical purposes, you can treat it as a duck. You don't need to know its official bird family or species. You just need to know it can do the duck-like things you expect.

Why is Duck Typing Useful?

Duck typing helps programmers write code that is more flexible. It means you don't have to be super strict about the exact "type" of every object. This can make programs easier to change and expand later.

For example, imagine you are building a game with many different kinds of characters. Some characters might be "Heroes," and others might be "Monsters." If both heroes and monsters need to be able to `attack()`, you don't need to check if they are a "Hero" or a "Monster." You just check if they have an `attack()` ability. If they do, you can tell them to attack.

Duck Typing in Programming

In programming, "types" are like categories for data. For example, a number is one type, and text is another. In some programming styles, you must always declare the exact type of an object. Duck typing is different.

It focuses on the behavior of an object. If an object has all the methods (actions) and properties (data) that your code needs, then your code can use it. It doesn't matter what its official "class" or "type" is.

An Example with Animals

Let's think about a simple program that makes animal sounds.

• You might have a `Dog` object that can `bark()`.
• You might have a `Cat` object that can `meow()`.
• You might have a `Duck` object that can `quack()`.

If you want to make a sound, you could write a function that takes any animal. Inside the function, you would check: "Does this animal have a `make_sound()` method?" If it does, you call that method.

This way, your function doesn't care if it's a dog, cat, or duck. It just cares if the animal can `make_sound()`. This is duck typing in action!

See also

In Spanish: Duck typing para niños