who‑calls

Who calls my function? — A tiny static caller‑tree explorer for Python.

who‑calls scans a project’s source code with the built‑in ast module, builds a directed call‑graph (caller → callee), and prints every call‑path that can reach a target function. Output is an ASCII tree whose nodes are clickable file‑and‑line references in most modern terminals and IDEs.

├── main @ app/entry.py:28
│   └── orchestrate @ app/tasks/flow.py:71
│       └── do_work @ app/worker.py:42  <─ target
└── cli_entry @ app/cli.py:13
    └── do_work @ app/worker.py:42  <─ target

✨ Features

• Static analysis only – no code execution, so it’s safe to run on untrusted repos or in CI.
• Clickable labels – format func @ path.py:LINE so VS Code, PyCharm, Zed, etc. jump straight to the definition.
• Regex‑based exclusion – skip vendored or generated code (.git, .venv, .cache, tests by default).
• Detects self.method() / cls.method() calls inside classes.
• Clear error on ambiguous target names; accepts fully‑qualified package.module:Class.method style.

🚀 Installation (with UV)

uv pip install who‑calls

UV? uv is a super‑fast drop‑in replacement for pip + virtualenv. If you prefer stock tools, replace uv pip with pip.

Dev / editable install

uv venv .venv && source .venv/bin/activate
uv pip install -e .[dev]

🛠️ CLI usage

who‑calls <function> [OPTIONS]

Options:
  --root DIR         Project root (default: current directory)
  --exclude REGEX    Regex of paths to ignore (default: \\ .git | .venv | .cache | tests)

Examples:

# show who can reach do_work()
who‑calls do_work

# fully‑qualified target
who‑calls app.worker.do_work

# scan ./src and ignore build folder
who‑calls process_order --root src --exclude "build|dist"

If the short name matches multiple symbols you’ll get:

⚠ Ambiguous function name. Matches:
  • app.utils.filters:create_filter
  • app.api.v1.picking_filters.queries:create_filter
Please specify full path like <module>.<func> or <module>.<Class>.<method>.

🔍 How it works (high‑level)

1. Recursively collect *.py files below --root, apply --exclude.

2. Parse each file with ast.parse.

3. Record every FunctionDef / AsyncFunctionDef with a fully‑qualified dotted name (pkg.mod.Class.func).

4. Discover call edges:

   • foo() → unique match by name.
   • self.foo() / cls.foo() → method on same class.
   • obj.foo() → falls back to unique global match.

5. Build a networkx.DiGraph, reverse it, keep only ancestors that can reach the target, then pretty‑print.

📦 Project structure

who‑calls/
├── pyproject.toml          # uv build backend
└── who_calls/
    ├── __init__.py         # exposes who_calls.main
    └── cli.py              # core logic (ast + networkx)

🖋️ License

MIT © 2025  janbjorge