TIL #143 – Resolve a lazy import manually

A couple of articles ago I wrote about how you could inspect a lazy import.

Apparently, you can use a similar trick to check the attributes and methods that a lazy import has:

>>> lazy import json
>>> dir(globals()["json"])
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getstate__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'resolve']

Apart from a large number of dunder methods and dunder attributes, you'll find the method resolve. You can run help(globals()["json"].resolve) to get the help text on that method:

Help on built-in function resolve:

resolve() method of builtins.lazy_import instance
    resolves the lazy import and returns the actual object

This shows that it's the method resolve that resolves a lazy import.

If you call the method, you can get access to the resolved module:

>>> lazy import json
>>> resolved_json = globals()["json"].resolve()
>>> resolved_json
<module 'json' from '/Users/rodrigogs/.local/share/uv/python/cpython-3.15.0a8-macos-aarch64-none/lib/python3.15/json/__init__.py'>

After calling resolve, the lazy module doesn't disappear automatically:

>>> globals()["json"]
<lazy_import 'json'>

Which shows that the mechanism that's responsible for reification most likely calls the method resolve and then reassigns the name of the module to the module returned by resolve. In a way, it's as if the reification process ran something like

globals()["json"] = globals()["json"].resolve()

In hindsight, this isn't too surprising. After all, Python tends to be very consistent. The only mistery that remains is what triggers the reification process. How is it that Python can detect when something touches the lazy import..?

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