wppm — the dependency questions pip won't answer

wppm is a small companion to pip, for any Python environment (it was born in WinPython, the portable Windows distribution, but does not require it). Keep using pip to install and remove things — use wppm to see what is actually there.

pip install wppm

Which extras of a package are actually usable here?

You installed flit. Its [doc] and [test] extras promise more. What is missing?

$ wppm -p "flit![.]"
flit[doc]==3.12.0 ,
    pygments-github-lexers==? ;extra==doc
    sphinx==? ;extra==doc
    sphinxcontrib-github-alt==? ;extra==doc
flit[test]==3.12.0 ,
    pytest-cov==? ;extra==test
    responses==? ;extra==test
    testpath==? ;extra==test
    tomli==? ;extra==test

[.] means every extra, ! means only show what is missing, and ==? marks a requirement that is not installed. Extras with nothing missing are simply not printed — so an empty answer means "everything this package offers is ready to use".

Drop the ! to see the whole picture instead, installed versions included:

$ wppm -p "requests[.]" -l1
requests==2.34.2 ,
    certifi==2026.6.17 >=2023.5.7
    charset-normalizer==3.4.9 <4,>=2
    idna==3.18 <4,>=2.5
    urllib3==2.7.0 <3,>=1.26
requests[socks]==2.34.2 ,
    certifi==2026.6.17 >=2023.5.7
    charset-normalizer==3.4.9 <4,>=2
    idna==3.18 <4,>=2.5
    pysocks==? !=1.5.7,>=1.5.6;extra==socks
    urllib3==2.7.0 <3,>=1.26
requests[use-chardet-on-py3]==2.34.2 ,
    certifi==2026.6.17 >=2023.5.7
    chardet==? <8,>=3.0.2;extra==use-chardet-on-py3
    charset-normalizer==3.4.9 <4,>=2
    idna==3.18 <4,>=2.5
    urllib3==2.7.0 <3,>=1.26

Who pulls in pytest, and through which extra?

The reverse direction, -r, is extras-aware too — it tells you why something is in your environment, down to the extra that asked for it:

$ wppm -r "pytest[.]"
pytest==9.0.3
pytest[all]==9.0.3 ,
    idna[all]==3.18 [requires: pytest>=8.3.2;extra==all]
    pandas[all]==3.0.3 [requires: pytest>=8.3.4;extra==all]
pytest[dev]==9.0.3
pytest[test]==9.0.3 ,
    flit[test]==3.12.0 [requires: pytest>=2.7.3;extra==test]
    pandas[test]==3.0.3 [requires: pytest>=8.3.4;extra==test]
pytest[testing]==9.0.3 ,
    pluggy[testing]==1.6.0 [requires: pytest;extra==testing]
pytest[tests]==9.0.3 ,
    pillow[tests]==12.3.0 [requires: pytest;extra==tests]

What will break when I upgrade?

With -r, the ! filter keeps only the packages that pin or cap the one you name — the handful that will actually fight your next upgrade, instead of the long list of packages that merely depend on it:

$ wppm -r "pluggy!"
pluggy==1.6.0 ,
    pytest==9.0.3 [requires: pluggy<2,>=1.5]

An empty answer here is good news: nothing constrains it, upgrade away.

And the whole constraint web of an environment — every package, every extra, nine levels deep — is one command:

$ wppm -p ".[.]" -l9

What did you actually ask for?

-p and -r answer for one package. -tl answers for a whole list: it keeps only the entries nothing else in that list already pulls in. Plainly, it prints that list and nothing else -- so the output is the new file, and the counts go to stderr where a redirection leaves them behind:

$ wppm requirements_slim.txt -tl -t D:\WPy64\python > requirements_slim_new.txt
# 160 entries -> 112 kept, 48 already pulled in
# 8 repeated, collapsed: brotli, openai, pympler, pytest, python-barcode, ...

Those two lines are commented although they go to stderr, so folding both streams into one file (> new.txt 2>&1) still leaves a file pip can read.

The notes the source file carried are kept, since they are its author's. -v adds the reasoning: what the list is made from and when, the same counts, and every dropped entry commented out with what pulls it in, so re-asking for one is uncommenting it. stderr then keeps quiet, the counts being in the file already.

$ wppm requirements_slim.txt -tl -v -t D:\WPy64\python
# requirements_slim.txt, sorted, 2026-08-13 19:22:43
# 160 entries -> 112 kept, 48 already pulled in
# 8 repeated, collapsed: brotli, openai, pympler, pytest, python-barcode, ...

...
#numpy  # <- baresql, clarabel, cvxpy, dask[array,dataframe,diagnostics], datashader, ...
#scikit-learn  # <- imbalanced-learn, mlxtend, prince, skrub, umap-learn
#whatthepatch  # <- spyder

With no file, the question becomes "of everything installed here, what did anything actually ask for?":

$ wppm --top-level -t D:\WPy64\python

An optional dependency only counts where its extra is asked for, and a mutual pair keeps both members -- dropping either would take the other with it. With -ws the facts come from a wheelhouse instead of an installation, so a list can be pruned before anything is built; where the wheelhouse holds several versions of a package, the newest one answers.

Everything is available as JSON

Any of -p, -r, -ls, -md accepts -j / --json, so the same answers can gate a CI job or be diffed between two environments:

$ wppm -p pluggy -j
[
    {
        "package": "pluggy",
        "extra": "",
        "version": "1.6.0",
        "installed": true,
        "constraint": "",
        "depends": []
    }
]

$ wppm -p myapp -j | python -c "import sys,json; s=json.load(sys.stdin); [s.extend(n['depends']) for n in s]; sys.exit(1 if any(not n['installed'] for n in s) else 0)"

Or use it from Python

The tree engine is a plain importable module — no subprocess, no parsing of terminal output. down() walks dependencies, up() walks them backwards, and both return indented text by default or a JSON string with format="json":

import json
from wppm import piptree

pip = piptree.PipData()                 # or PipData(target=r"D:\WPy64\python")

tree = json.loads(pip.down("pandas", "mysql", format="json"))
missing = [d["package"] for d in tree[0]["depends"] if not d["installed"]]
print(f"pandas[mysql] needs: {missing}")

pandas[mysql] needs: ['pymysql', 'sqlalchemy']

>>> print(pip.up("pluggy!"))     # who caps pluggy?
pluggy==1.6.0 ,
    pytest==9.0.3 [requires: pluggy<2,>=1.5]
>>> pip.summary("pandas")
'Powerful data structures for data analysis, time series, and statistics'

It also works on environments you have not installed anything into

-t points wppm at another Python distribution, and -ws at a plain directory of wheels — so you can inspect a portable distribution, or an offline bundle, without installing it first:

$ wppm -ls -ws .\wheelhouse\included.wheels --json
$ wppm -p "pandas[.]" -t D:\WPy64\python

Beyond inspection, wppm installs from a wheelhouse or a pylock.toml (-i, -ws, -wd), emits a one-document environment manifest — distribution, tools, packages, wheelhouse — as Markdown or JSON (-md, a lightweight SBOM), and does portability housekeeping: on any Windows Python, --movable / --fix rewrite the Scripts\ launchers and shebangs between relative and absolute paths, so a directory can be moved (or pinned back down) without breaking its entry points.

--register / --unregister associate file extensions, icons, context menu and start menu entries with the target Python. Each distribution gets its own start menu folder, so registering one never disturbs another — but note that the target is declared under the WinPython PEP-514 vendor key.

Compared with pipdeptree

wppm adds per-[extra] granularity in both directions, the ! filter (missing dependencies forward, constraining dependencies backward), and the ability to inspect another environment (-t) or a bare directory of wheels (-ws) without installing anything into it.

Quoting: ! and [ are shell metacharacters in POSIX shells, so quote the argument (wppm -p "flit![.]"). In cmd.exe the quotes are optional.

Command line

usage: wppm [-h] [-v] [--register] [--unregister] [--fix] [--movable]
            [-ws WHEELSOURCE] [-wd WHEELDRAIN] [-ls] [-lsa] [-md] [-p] [-r]
            [-tl] [-l LEVELS] [-j] [-t TARGET] [-i] [-u]
            [package(s) or lockfile ...]

WinPython Package Manager: handle a Python distribution (WinPython or not) and its packages (17.11.20260813)

positional arguments:
  package(s) or lockfile
                        optional package names, wheels, or lockfile

options:
  -h, --help            show this help message and exit
  -v, --verbose         show more details on packages and actions
  --register            Register the target Python in Windows (file extensions, icons, context menu, start menu), under the 'WinPython' PEP-514 vendor key
  --unregister          Unregister the target Python from Windows: de-associate file extensions, icons and context menu, and remove its start menu folder
  --fix                 make the target Python use absolute (fixed) paths in launchers and shebangs
  --movable             make the target Python (any Windows Python) movable/portable: relative paths in launchers and shebangs
  -ws WHEELSOURCE       wheels location, ('.' = WheelHouse): wppm pylock.toml -ws source_of_wheels, wppm -ls -ws .
  -wd WHEELDRAIN        wheels destination: wppm pylock.toml -wd destination_of_wheels
  -ls, --list           list installed packages matching [optional] expression: wppm -ls, wppm -ls pand
  -lsa                  list details of packages matching [optional]  expression: wppm -lsa pandas -l1
  -md                   markdown summary of the installation
  -p                    show Package (!= missing) dependencies of the given package[option], [.]=all: wppm -p pandas[.]
  -r                    show Reverse (!= constraining) dependancies of the given package[option]: wppm -r pytest![test]
  -tl, --top-level      keep only the entries no other entry pulls in, sorted: wppm -tl, wppm requirements.txt -tl -v
  -l LEVELS             show 'LEVELS' levels of dependencies (with -p, -r): wppm -p pandas -l1
  -j, --json            machine-readable JSON output (with -p, -r, -ls, -md, -tl): wppm -p pandas[.] -j
  -t TARGET             path to target Python distribution (default: current environment)
  -i, --install         install a given package wheel or pylock file (use pip for more features)
  -u, --uninstall       uninstall package  (use pip for more features)

Links

• Source code: https://github.com/winpython/winpython
• Issues and feature requests: https://github.com/winpython/winpython/issues
• Discussions: https://github.com/winpython/winpython/discussions
• WinPython distribution: https://winpython.github.io/