missing

library5.2pypypiunverified

Provides the `Missing` class and related sentinel objects used throughout Zope to represent missing or undefined values. Current version: 5.2. Maintained by the Zope Foundation. Release cadence: irregular, tied to Zope releases.

testing

pip install missing

github ↗homepage ↗

INSTALL

IMPORT

SIG · MISSING

missing

testingpythonv5.2

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

Missing

✓ from missing import Missing

✗ from missing import Missing

Base

✓ from missing import Base

✓ from missing import V

Basic usage of the Missing sentinel.

from missing import Missing # Use Missing as a sentinel for absent values def get_value(d, key): return d.get(key, Missing) result = get_value({'a': 1}, 'b') print(result is Missing) # True # Missing is falsy if not result: print('Value is missing')

Debug

Known issues

gotchaDo not use `Missing` as a default argument in function signatures; use sentinel patterns or `None` with explicit checks instead. `Missing` is a mutable singleton, which can lead to unexpected behavior if modified.

fix

Define a custom sentinel: `_sentinel = object()` or use `None` with `if arg is None`.

affects: all

gotcha`Missing` is falsy (`bool(Missing) == False`). This can cause subtle bugs when checking truthiness of a value that could be `Missing`.

fix

Use `is Missing` for identity checks instead of truthiness checks.

affects: all

deprecatedDirect import from `Missing` (capital M) is deprecated in favor of `from missing import Missing`.

fix

Use `from missing import Missing`.

affects: >=4.0

Upgrade

Version history

5.2latest on PyPI · released May 8, 2026

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/zopefoundation/Missing ↗

homepagehttps://github.com/zopefoundation/Missing ↗