The Python Apprentice

Dynamic typing in Python

Dynamic typing means that the type of an object-reference isn't resolved until the program is running, and it needn't be specified up front when the program is written. Take a look at this simple function for adding two objects:

>>> def add(a, b):...     return a + b...

Nowhere in this definition do we mention any types. We can use add() with integers:

>>> add(5, 7):12

And we can use it for floats:

>>> add(3.1, 2.4)5.5

You might be surprised to see that it even works for strings:

>>> add("news", "paper")'newspaper'

Indeed, this function works for any types, like list, for which the addition operator has been defined:

>>> add([1, 6], [21, 107])[1, 6, 21, 107]

These examples illustrate the dynamism of the type system: The ...