no-value 1.0.0

Sentinel value for missing data where None has its own meaning

no-value

Sentinel value to express missing keys or values where None has its own meaning.

Why?

When building APIs or update operations, you often need to distinguish between:

• a value — set the field
• None — clear the field
• not provided — leave the field unchanged

Python's None can't cover both "clear" and "not provided". NoValue fills that gap.

Installation

pip install no-value

Usage

from no_value import NoValue


def update_user(name: str | None | NoValue = NoValue) -> None:
    if name is NoValue:
        pass  # not provided, do nothing
    elif name is None:
        clear_name()  # explicitly set to null
    else:
        set_name(name)  # update with new value

Behavior

• Use is for comparison: val is NoValue
• str(NoValue) and repr(NoValue) return "NoValue"
• NoValue() raises TypeError — it cannot be instantiated
• bool(NoValue) raises TypeError — to prevent accidental truthy/falsy checks

Limitations

Static analysis tools (mypy, pyright) do not fully support custom sentinel types. Type annotations like str | None | NoValue work at runtime but may produce warnings in strict mode.

License

MIT