Types

Calling type(foo) returns the actual class object of which foo is an instance (that is, not foo’s class’s name (a string), but rather the actual class object).

type(3)          #=> int
type(3.1)        #=> float
type('hi')       #=> str
type([1,2])      #=> list
type((5,7))      #=> tuple
type({'a': 1})   #=> dict
type(set(8,9))   #=> set

def f(x): pass
type(f)          #=> function

type(max)        #=> builtin_function_or_method

import sys
type(sys)        #=> module

Note that although you usually capitalize the names of your own types/classes, by Python convention those built-in types above are all named lowercase.

Ints automatically widen to floats. To convert between other types, pass the object to the new type’s constructor.

3 + 1.0       #=> 4.1 (a float)
3 + '1'       # throws TypeError
3 + int('1')  #=> 4
str(3) + '1'  #=> '31'