%pfile doesn't detect objects from the standard library

[illright]

Steps to reproduce

• Execute import math
• Execute %pfile math
• Execute %pfile math.log

Expected result

Both calls to %pfile tell the user that math is a part of the standard library

Actual result

Both calls to %pfile produce an error:

No file found for math
No file found for math.log

System info

Manjaro Linux, Python 3.9.4, IPython 7.22.0 (reproduces on IPython 8.0.0.dev)

[MrMino]

I don't think this would be the right result for pfile. You can run this on standard library without any problem, e.g. %pfile telnetlib. The issue pfile has with math is not that it is a standard library, but rather that it cannot find the python source code file the module points to, since it's a compiled binary. There's no source file - hence "No file found".

[illright]

I think it could be helpful to point users towards the standard library in such cases, regardless of their setup.

Also, I don't really understand the mechanics of %pfile. I created a file test.py in the current directory with the contents specific_var = 5, then executed from test import specific_var and then %pfile specific_var. I expected it to point me towards file.py, but it also printed out No file found for specific_var.

[MrMino]

I disagree. It would be very difficult to tell whether something is actually stdlib or not, you'd have to maintain a list throughout each platform × python version, which would be a nightmare'ish endeavour.

I expected it to point me towards file.py, but it also printed out No file found for specific_var.

As I understand it, you're giving it the value 5, which is not defined anywhere where %pfile can look. The docs say:

Print (or run through pager) the source code for an object.

5 is not defined in your file, and you cannot get its source code by using Python's introspection tools, hence No file found for specific_var.