XS::Framework::Manual::recipe05 - XS::Framework basics


XS::libpanda offers lightweight intrusive smart pointer iptr. Please, referer intrusive pointer from Boost library for introduction. The easiest way to add refcounted property to C++ class is to inherit from panda::Refcnt (1):

    struct TimezoneRecipe05: public panda::Refcnt {
        //                                  (1)
        const char* get_name() const { return name.c_str(); }
        TimezoneRecipe05(const char* name_): name{name_} { }
        ~TimezoneRecipe05() { std::cerr << "~TimezoneRecipe05()\n"; }
        std::string name;

    using TimezoneRecipe05SP = panda::iptr<TimezoneRecipe05>;

Let's define typemap for timezone:

    namespace xs {
        template <>
        struct Typemap<TimezoneRecipe05*> : TypemapObject<TimezoneRecipe05*, TimezoneRecipe05*, ObjectTypeRefcntPtr, ObjectStorageMG, StaticCast> {
            ///             (2)                                                                       (e)
            static std::string package () { return "MyTest::Cookbook::TimezoneRecipe05"; }

The typemap specialization (2) should be for timezone pointer (TimezoneRecipe05*), as XS::Framework ships with auto-deduced typemaps for iptr<T>. The ObjectTypeRefcntPtr lifetime policy should be specified.

There is no constraint for C++ class to let it inherit panda::Refcnt: all is needed is that the class with refcounter semantics should define global functions refcnt_inc, refcnt_dec and refcnt_get.

The xs-adapter is trivial; it should be defined for timezone pointer:

    MODULE = MyTest                PACKAGE = MyTest::Cookbook::TimezoneRecipe05

    const char* TimezoneRecipe05::get_name() { RETVAL = THIS->get_name(); }

    TimezoneRecipe05SP create(const char* name) { RETVAL = TimezoneRecipe05SP(new TimezoneRecipe05(name)); }

For the sake of completeness there is another mapped C++ class, which uses TimezoneRecipe05SP. There is nothing new for a reader familiar with the previous recipes.

    // C++ class
    struct DateRecipe05 {
        DateRecipe05()  { update() ; }
        void update()   { epoch = std::time(nullptr); }

        int get_epoch() const { return epoch; }
        void set_timezone(TimezoneRecipe05SP tz_) { tz = tz_; }
        TimezoneRecipe05SP get_timezone() { return tz; }
        std::time_t epoch;
        TimezoneRecipe05SP tz;

    // typemap
    namespace xs {
        template <>
        struct Typemap<DateRecipe05*> : TypemapObject<DateRecipe05*, DateRecipe05*, ObjectTypePtr, ObjectStorageMG, StaticCast> {
            static std::string package () { return "MyTest::Cookbook::DateRecipe05"; }

    // xs-adapter
    MODULE = MyTest                PACKAGE = MyTest::Cookbook::DateRecipe05

    DateRecipe05* DateRecipe05::new() { RETVAL = new DateRecipe05(); }

    void DateRecipe05::update()

    std::time_t DateRecipe05::get_epoch()

    TimezoneRecipe05SP DateRecipe05::get_timezone()

    void DateRecipe05::set_timezone(TimezoneRecipe05SP tz)

The SV* wrapper identity is not preserved when it is set to Date and returned back, i.e. the same as in previous recipe.