TIL #141 – Inspect a lazy import

programming python

Python 3.15 comes with lazy imports and today I played with them for a minute. I defined the following module mod.py:

print("Hey!")

def f():
    return "Bye!"

Then, in the REPL, I could check that lazy imports indeed work:

>>> # Python 3.15
>>> lazy import mod
>>>

The fact that I didn't see a "Hey!" means that the import is, indeed, lazy. Then, I wanted to take a look at the module so I printed it, but that triggered reification (going from a lazy import to a regular module):

>>> print(mod)
Hey!
<module 'mod' from '/Users/rodrigogs/Documents/tmp/mod.py'>

So, I checked the PEP that introduced explicit lazy modules and turns out as soon as you reference the lazy object directly, it gets reified. But you can work around it by using globals:

>>> # Fresh 3.15 REPL
>>> lazy import mod
>>> globals()["mod"]
<lazy_import 'mod'>

This shows the new class lazy_import that was added to support lazy imports!

Pretty cool, right?

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