Functions in Python can be nested inside other functions.
A function defined inside a function is visible only inside that function.
This is useful to create utilities that are useful to a function, but not useful outside of it.
You might ask: why should I be “hiding” this function, if it does not harm?
One, because it’s always best to hide functionality that’s local to a function, and not useful elsewhere.
Also, because we can make use of closures (more on this later).
Here is an example:
def talk(phrase):
def say(word):
print(word)
words = phrase.split(' ')
for word in words:
say(word)
talk('I am going to buy the milk')
If you want to access a variable defined in the outer function from the inner function, you first need to declare it as nonlocal:
def count():
count = 0
def increment():
nonlocal count
count = count + 1
print(count)
increment()
count()
This is useful especially with closures, as we’ll see later.
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It's a 10-weeks long cohort online course where I will guide you to becoming a Web Developer.
It's not "just a course". It's a big event I organize once a year.
We'll start from zero, learn the fundamentals of Web Development, HTML CSS, JavaScript, Tailwind, Git, using the command line, VS Code, GitHub, Node.js, we'll then learn React, JSX, how to use PostgreSQL, Astro, Next.js, Prisma, deploying on Netlify/DigitalOcean/Fly/Vercel and much more!
At the end of the first 10 weeks you'll know how to create web sites and web applications and I'll unlock you the 2nd phase of the Bootcamp: you will get access to a large number of projects exclusive to the Bootcamp graduates, so you can follow my instructions to build things like private areas with authentication, clones of popular sites like Twitter YouTube Reddit, create e-commerce sites, and much much more.
Because once you got the fundamentals, you only learn by working on real, exciting projects.
To find out more, visit bootcamp.dev