Method load

include/pybind11/cast.h:508–558

    static constexpr size_t UTF_N = 8 * sizeof(CharT);

    bool load(handle src, bool) {
        handle load_src = src;
        if (!src) {
            return false;
        }
        if (!PyUnicode_Check(load_src.ptr())) {
            return load_raw(load_src);
        }

        // For UTF-8 we avoid the need for a temporary `bytes` object by using
        // `PyUnicode_AsUTF8AndSize`.
        if (UTF_N == 8) {
            Py_ssize_t size = -1;
            const auto *buffer
                = reinterpret_cast<const CharT *>(PyUnicode_AsUTF8AndSize(load_src.ptr(), &size));
            if (!buffer) {
                PyErr_Clear();
                return false;
            }
            value = StringType(buffer, static_cast<size_t>(size));
            return true;
        }

        auto utfNbytes
            = reinterpret_steal<object>(PyUnicode_AsEncodedString(load_src.ptr(),
                                                                  UTF_N == 8    ? "utf-8"
                                                                  : UTF_N == 16 ? "utf-16"
                                                                                : "utf-32",
                                                                  nullptr));
        if (!utfNbytes) {
            PyErr_Clear();
            return false;
        }

        const auto *buffer
            = reinterpret_cast<const CharT *>(PYBIND11_BYTES_AS_STRING(utfNbytes.ptr()));
        size_t length = static_cast<size_t>(PYBIND11_BYTES_SIZE(utfNbytes.ptr())) / sizeof(CharT);
        // Skip BOM for UTF-16/32
        if (UTF_N > 8) {
            buffer++;
            length--;
        }
        value = StringType(buffer, length);

        // If we're loading a string_view we need to keep the encoded Python object alive:
        if (IsView) {
            loader_life_support::add_patient(utfNbytes);
        }

        return true;
    }

    static handle
    cast(const StringType &src, return_value_policy /* policy */, handle /* parent */) {