Publicly expose `Lib/dbm/__init__.py::__main__` as a script

[erlend-aasland]

Bug report

Lib/dbm/__init__.py contains a tiny if __name__ == "__main__" section that repeatedly calls dbm.whichdb on each of the given arguments:

cpython/Lib/dbm/__init__.py

Lines 188 to 190 in 841eacd

	if __name__ == "__main__":
	for filename in sys.argv[1:]:
	print(whichdb(filename) or "UNKNOWN", filename)

Test session:

$ python3
Python 3.13.0a3+ (heads/main-dirty:841eacd076, Jan 26 2024, 00:39:26) [Clang 15.0.0 (clang-1500.1.0.2.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import dbm
>>> import dbm.gnu
>>> import dbm.ndbm
>>> import dbm.dumb
>>> dbm.gnu.open("gnu.db", "c").close()
>>> dbm.ndbm.open("ndbm.db", "c").close()
>>> dbm.dumb.open("dumb.db", "c").close()
$ python3 -m dbm gnu.db ndbm.db dumb.db other.db
python3: No module named dbm.__main__; 'dbm' is a package and cannot be directly execute
$ python3 -m dbm.__init__ gnu.db ndbm.db dumb.db other.db
dbm.dumb dumb.db
dbm.gnu gnu.db
dbm.ndbm ndbm.db
UNKNOWN other.db

Some observations:

• there is no __main__.py; we must execute __init__.py in order to run the script
• there is no real CLI; just a list of arguments

Suggesting either to:

1. remove the script
2. promote it, by improving it (create __main__.py, add docs, add a simple argparse CLI, ...)

Linked PRs

• gh-114576: Add command-line interface for dbm module #137893

[erlend-aasland]

FTR, I suggest the latter: let's improve the CLI and promote it in the dbm docs.

[erlend-aasland]

bug/feature; hard to say :)

[picnixz]

I would say it's a feature. It's not documented, just in an __init__.py that we must execute, so it's as if it's a very internal feature. To expose it publicly looks to me like a new feature so I'm tempted to remove the type-bug label. (I've added the triaged label to be sure that I don't look at it again to detect issues with bug and feature labels)

[erlend-aasland]

Yeah, I agree it's a feature. I do think it would be nice to add this, though.

[serhiy-storchaka]

If add such feature, the CLI should support several subcommands like whichdb, dump, reorganize, etc.