How to Escape { in Python

Last week, I was faced with an intriguing question. How do I escape { when using str.format in Python?

str.format(*args, **kwargs) is a function that can be used to perform string formatting. Explicit, huh? A simple example of using str.format is:

    >>> "Hello {}!".format("World")
    'Hello World!'

But…what if you need to format a string that actually has the character { in it, such as a “Hello {World}!”? It is actually fairly simple. From Format String Syntax:

Format strings contain “replacement fields” surrounded by curly braces {}. Anything that is not contained in braces is considered literal text, which is copied unchanged to the output. If you need to include a brace character in the literal text, it can be escaped by doubling: **{{** and **}}**.

So, our initial example would be:

    >>> "Hello {{{}}}!".format("World")
    'Hello {World}!'

That’s right, you need 3 braces! {{ turns into { once the string is formatted, }} turns into } once the string is formatted and the middle {} are the braces that actually allow you to dynamically format the string.

A few more examples:

    >>> "Hello {{{}}}!".format("World")
    'Hello {World}!'
    >>> "{{".format("World")
    '{'
    >>> "}}".format("World")
    '}'
    >>> "{}".format("World")
    'World'

It turns out that this is much simpler than I thought it would be. It took me a lot more time to find out. I assume that was because I wasn’t using the appropriate keywords and I ended up reading the manual - which is what I should have done in the first place.

P.S.: Immediately after this, I found the following StackOverflow answers, explaining exactly the same.

Originally published at https://hugomartins.io on November 11, 2019.