Scope and closures in Python

Where names live: local, global, and captured.

counter = 0


def bump():
    global counter
    counter += 1


def make_greeter(greeting):
    def greet(name):
        return f"{greeting}, {name}!"
    return greet


hello = make_greeter("Hello")
hola = make_greeter("Hola")
message = hello("world")

How it works

1. global lets a function rebind a module-level name.
2. make_greeter returns an inner function.
3. The inner function remembers greeting after its maker returns.

Keywords and builtins used here

• bump
• def
• global
• greet
• make_greeter
• return

The run, in numbers

Lines

17

Characters to type

228

Tokens

64

Three-star pace

95 tpm

At the three-star pace of 95 tokens a minute, this run takes about 40 seconds.

Type this snippet

Step 6 of 6 in Functions, step 38 of 72 in Language basics.

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