Naming convention for runtime-compiled modules?

[gukoff]

Context

Debugpy uses the frame's co_filename in many ways. It uses it for debuginfo caching, to determine whether it's user code or not (which affects behavior of the setting justMyCode), and whether to interpret the source code as raw Python code or Python bytecode.

For example, the filename is handled differently if it begins with <. It is considered non-user code not sourced from a file:

• debugpy/src/debugpy/_vendored/pydevd/pydevd_file_utils.py

  Line 481 in 1aff9aa

  if filename.startswith("<"):

• debugpy/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_constants.py

  Line 62 in 1aff9aa

  LIBRARY_CODE_BASENAMES_STARTING_WITH = ("<",)

• debugpy/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_api.py

  Line 535 in 1aff9aa

  if adjust_line and not translated_absolute_filename.startswith("<"):

Some more special names include:

debugpy/src/debugpy/_vendored/pydevd/_pydevd_bundle/pydevd_constants.py

Lines 47 to 59 in 1aff9aa

	# Any filename that starts with these strings is not traced nor shown to the user.
	# In Python 3.7 "<frozen ..." appears multiple times during import and should be ignored for the user.
	# In PyPy "<builtin> ..." can appear and should be ignored for the user.
	# <attrs is used internally by attrs
	# <__array_function__ is used by numpy
	IGNORE_BASENAMES_STARTING_WITH = ("<frozen ", "<builtin", "<attrs", "<__array_function__")
	# Note: <string> has special heuristics to know whether it should be traced or not (it's part of
	# user code when it's the <string> used in python -c and part of the library otherwise).
	# Any filename that starts with these strings is considered user (project) code. Note
	# that files for which we have a source mapping are also considered as a part of the project.
	USER_CODE_BASENAMES_STARTING_WITH = ("<ipython",)

It is also important whether the file ends with ".py", as in this case inspecting this file in VSCode enables syntax highlighting.

This works well for the regular Python files. But there is an edge case of runtime-compiled modules for which you can assign the filename dynamically. For example: https://github.com/wbond/pymeta3/blob/master/pymeta/builder.py#L309-L326

Question

How do I pick the name for a runtime-compiled module (not backed up by an actual source file) so that it plays well with debugpy?

• If the filename starts with /, debugpy interprets this runtime-compiled module as user code, even if everything happens in a library. This may lead to cryptic errors.
• If the filename is something like <generated myfile.py>, VSCode renders it as Python bytecode even when Python code is available for the frame.
• If the file doesn't begin with < or /, it's normalized to a non-existent file path under .../site-packages/{filename}.

What works well is a filename such as <generated>myfile.py. It begins with < and ends with .py, which ensures a correct interpretation. I wonder if such a naming makes sense from the point of view of debugpy, and whether there's a better way to achieve my goal that I'm missing.