Different output from importlib.resources.files() in REPL in 3.12 versus 3.13

[danielhollas]

Bug report

Bug description:

Running importlib.resources.files() without specifying the anchor parameter in interactive REPL in Python 3.12 raises a rather unhelpful error:

>>> import importlib.resources
>>> importlib.resources.files()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib64/python3.12/importlib/resources/_common.py", line 45, in wrapper
    return func()
           ^^
  File "/usr/lib64/python3.12/importlib/resources/_common.py", line 56, in files
    return from_package(resolve(anchor))
           ^^
  File "/usr/lib64/python3.12/importlib/resources/_common.py", line 113, in from_package
    reader = spec.loader.get_resource_reader(spec.name)
                                             ^^
  File "/usr/lib64/python3.12/importlib/resources/_adapters.py", line 17, in __getattr__
    return getattr(self.spec, name)
           ^^
AttributeError: 'NoneType' object has no attribute 'name'

It would be nice to return something more helpful. The documentation doesn't mention that this function can raise, so I am assuming that raising AttributeError is not part of the public API?

However, on a locally built Python from current main branch, this call returns a path to Lib/_pyrepl. Even more surprising though is that this also happens when running the OLD REPL with TERM=dumb ./python

❯ TERM=dumb ./python 
Python 3.14.0a0 (heads/main:1a84bdc237, Jun 30 2024, 21:44:46) [GCC 13.3.1 20240522 (Red Hat 13.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
warning: can't use pyrepl: terminal doesn't have the required clear capability
>>> import importlib.resources
>>> importlib.resources.files()
PosixPath('/home/hollas/software/cpython/Lib/_pyrepl')

CPython versions tested on:

3.12, CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-121190: A better error message from importlib.resources.files() when module spec is None #138531

[lysnikolaou]

Even more surprising though is that this also happens when running the OLD REPL with TERM=dumb ./python

TERM=dumb does not enable the old REPL. The env var is called PYTHON_BASIC_REPL.

[danielhollas]

TERM=dumb does not enable the old REPL. The env var is called PYTHON_BASIC_REPL.

Well, while it may not enable it explicitly, implicitly it does since pyrepl will not start with this type of terminal.

❯ TERM=DUMB ./python 
Python 3.14.0a0 (heads/main:1a84bdc237, Jun 30 2024, 21:44:46) [GCC 13.3.1 20240522 (Red Hat 13.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
warning: can't use pyrepl: setupterm: could not find terminal
>>> import importlib.resources
>>> importlib.resources.files()
PosixPath('/home/hollas/software/cpython/Lib/_pyrepl')

But you are right that actually using PYTHON_BASIC_REPL will actually run the old REPL directly, and will produce the same behaviour as in 3.12

❯ PYTHON_BASIC_REPL=1 ./python 
Python 3.14.0a0 (heads/main:1a84bdc237, Jun 30 2024, 21:44:46) [GCC 13.3.1 20240522 (Red Hat 13.3.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import importlib.resources
>>> importlib.resources.files()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    importlib.resources.files()
    ~~^
  File "/home/hollas/software/cpython/Lib/importlib/resources/_common.py", line 45, in wrapper
    return func()
  File "/home/hollas/software/cpython/Lib/importlib/resources/_common.py", line 56, in files
    return from_package(resolve(anchor))
  File "/home/hollas/software/cpython/Lib/importlib/resources/_common.py", line 116, in from_package
    reader = spec.loader.get_resource_reader(spec.name)
                                             ^^
  File "/home/hollas/software/cpython/Lib/importlib/resources/_adapters.py", line 17, in __getattr__
    return getattr(self.spec, name)
AttributeError: 'NoneType' object has no attribute 'name'
>>>

Note that I am not saying that the pyrepl behaviour is wrong here, just noting the difference. If anything, I'd change the behaviour in the old REPL so that at least it fails a bit more gracefully (not an obscure AttributeError).

[whitphx]

#134275 should fix the new REPL's different behavior than the old one,
while the issue below still is there

It would be nice to return something more helpful. The documentation doesn't mention that this function can raise, so I am assuming that raising AttributeError is not part of the public API?

[whitphx]

Hi from PyConTW sprint.

SpecLoaderAdapter accesses spec's attributes such as spec.name

cpython/Lib/importlib/resources/_adapters.py

Line 17 in fc0305a

return getattr(self.spec, name)

while spec can be None when the package is __main__ as documented.

cpython/Lib/importlib/resources/_adapters.py

Line 168 in fc0305a

return SpecLoaderAdapter(package.__spec__, TraversableResourcesLoader)

importlib.resources._common.from_package(package) needs to take care of the case where package.__spec__ is None.

Let me take a closer look...

---

• Code around it was introduced in bpo-42129: Add support for resources in namespaces #24670
• Looks like the PR intended to make importlib.resources synched with https://github.com/python/importlib_resources, and importlib_resources also has the same problem as this issue.

>>> import importlib_resources
>>> importlib_resources.files()
Traceback (most recent call last):
  File "<python-input-1>", line 1, in <module>
    importlib_resources.files()
    ~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/workspace/cpython/.venv/lib/python3.15/site-packages/importlib_resources/_adapters.py", line 17, in __getattr__
    return getattr(self.spec, name)
AttributeError: 'NoneType' object has no attribute 'name'