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Added option to add return_name to custom type_caster.

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This allows to define different python type hints for arguments and
return value. This is implemented using template class `as_return_type`
in order to check if `return_name` is available in the `type_caster` at
compile time. If `return_name` is not available, it falls back to the
previous usage of `name` for both args and return value.
This commit is contained in:
Tim Ohliger 2024-09-06 14:25:42 +02:00
parent 8a801bdc32
commit dd829c5994
1 changed files with 27 additions and 1 deletions
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28
include/pybind11/pybind11.h
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@ -101,6 +101,31 @@ inline std::string replace_newlines_and_squash(const char *text) {
# define PYBIND11_COMPAT_STRDUP strdup
#endif
/// Type trait checker for `descr`.
template<typename>
struct is_descr : std::false_type {};
template<size_t N, typename... Ts>
struct is_descr<descr<N, Ts...>> : std::true_type {};
template<size_t N, typename... Ts>
struct is_descr<const descr<N, Ts...>> : std::true_type {};
/// Checks for `return_name` in `type_caster` to replace `name` for return type hints.
/// this is useful for having a different python type hint for args vs return value,
/// e.g., `std::filesystem::path` -> Arg: `Union[os.PathLike, str, bytes]`, return: `Path`.
template<typename T, typename Enable = void>
struct as_return_type
{
static constexpr auto name = T::name;
};
template <typename T>
struct as_return_type<T, typename std::enable_if_t<is_descr<decltype(T::return_name)>::value>>
{
static constexpr auto name = T::return_name;
};
PYBIND11_NAMESPACE_END(detail)
/// Wraps an arbitrary C++ function/method/lambda function/.. into a callable Python object
@ -320,7 +345,8 @@ protected:
/* Generate a readable signature describing the function's arguments and return
value types */
static constexpr auto signature
= const_name("(") + cast_in::arg_names + const_name(") -> ") + cast_out::name;
= const_name("(") + cast_in::arg_names + const_name(") -> ")
+ as_return_type<cast_out>::name;
PYBIND11_DESCR_CONSTEXPR auto types = decltype(signature)::types();
/* Register the function with Python from generic (non-templated) code */