Cool New Features in Python 3.7

Python 3.7: Cool New Features for You to Try

by Geir Arne Hjelle Reading time estimate 29m python
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Python 3.7 is officially released! This new Python version has been in development since September 2016, and now we all get to enjoy the results of the core developers’ hard work.

What does the new Python version bring? While the documentation gives a good overview of the new features, this article will take a deep dive into some of the biggest pieces of news. These include:

  • Easier access to debuggers through a new breakpoint() built-in
  • Simple class creation using data classes
  • Customized access to module attributes
  • Improved support for type hinting
  • Higher precision timing functions

More importantly, Python 3.7 is fast.

In the final sections of this article, you’ll read more about this speed, as well as some of the other cool features of Python 3.7. You will also get some advice on upgrading to the new version.

The breakpoint() Built-In

While we might strive to write perfect code, the simple truth is that we never do. Debugging is an important part of programming. Python 3.7 introduces the new built-in function breakpoint(). This does not really add any new functionality to Python, but it makes using debuggers more flexible and intuitive.

Assume that you have the following buggy code in the file bugs.py:

Language: Python 
def divide(e, f):
    return f / e

a, b = 0, 1
print(divide(a, b))

Running the code causes a ZeroDivisionError inside the divide() function. Let’s say that you want to interrupt your code and drop into a debugger right at the top of divide(). You can do so by setting a so called “breakpoint” in your code:

Language: Python 
def divide(e, f):
    # Insert breakpoint here
    return f / e

A breakpoint is a signal inside your code that execution should temporarily stop, so that you can look around at the current state of the program. How do you place the breakpoint? In Python 3.6 and below, you use this somewhat cryptic line:

Language: Python 
def divide(e, f):
    import pdb; pdb.set_trace()
    return f / e

Here, pdb is the Python Debugger from the standard library. In Python 3.7, you can use the new breakpoint() function call as a shortcut instead:

Language: Python 
def divide(e, f):
    breakpoint()
    return f / e

In the background, breakpoint() is first importing pdb and then calling pdb.set_trace() for you. The obvious benefits are that breakpoint() is easier to remember and that you only need to type 12 characters instead of 27. However, the real bonus of using breakpoint() is its customizability.

Run your bugs.py script with breakpoint():