Wrapper to type-hint return values in Python that maybe None but not likely. More...

#include <maybe_none.h>

Public Member Functions
T &	reference ()
	Return reference to wrapped value.

const T &	reference () const
	Return reference to wrapped value.

Detailed Description

template<typename T>
class lass::python::MaybeNone< T >

Wrapper to type-hint return values in Python that maybe None but not likely.

Use this class to wrap a type T that could be None in Python (for example, a pointer type), but it is not likely to be None and forcing the user to expliclitly check for None can more painful than helpful. Annotating the type as T | MaybeNone instead of T | None will make static type-checkers like mypy ignore the None case, while still allowing the user to check for None if they want to. See The Any Trick for more information.

Note: This class does NOT prevent None values from being passed or returned, and it does NOT provide any runtime or compile-time checks whatsoever. It only alters the type-hint in Python for static type-checkers.

MaybeNone<T> types can only be returned from C++ to Python, it doesn't make sense to have them as function parameters in C++.

Built-in support for MaybeNone is provided for raw pointers T*, util::SharedPtr<T>, std::shared_ptr<T>, and std::optional<T>. To support your own types, you must specialize PyExportTraits, see PyExportTraitsMaybeNone for more information.

See also: PyExportTraitsMaybeNone; PyExportTraits<MaybeNone<T*>>; PyExportTraits<MaybeNone<util::SharedPtr<T,S,C>>>; PyExportTraits<MaybeNone<std::shared_ptr<T>>>; PyExportTraits<MaybeNone<std::optional<T>>>; NoNone

Definition at line 81 of file maybe_none.h.

The documentation for this class was generated from the following file:

maybe_none.h

Public Member Functions

Detailed Description