Den 2018-02-23 kl. 15:36, skrev Pavlo Solntsev:
>>> Your concern is justified. The Glib::ustring must be returned by value. The _MEMBER_GET should be
It is interesting. getter must return by value....

>>> Your _MEMBER_SET macro doesn't seem to fit the generated code that you show. I would think that
>>> _MEMBER_SET(name, name, const Glib::ustring&, gchar*)

from https://github.com/GNOME/glibmm/blob/master/tools/m4/member.m4
My understanding that the generated type will be const T& if T is provided to the macros.

dnl Creates accessors for simple types:

        define(`_MEMBER_SET',`dnl

        ifelse(`$5',`deprecated',`_DEPRECATE_IFDEF_START ')dnl

        void set_$1(const $3`'& value);

        ifelse(`$5',`deprecated',`_DEPRECATE_IFDEF_END ')dnl

        _PUSH(SECTION_CC)

        ifelse(`$5',`deprecated',`_DEPRECATE_IFDEF_START ')dnl

        void __CPPNAME__::set_$1(const $3`'& value)

        {

        gobj()->$2 = _CONVERT($3,$4,`value');

        }

        ifelse(`$5',`deprecated',`_DEPRECATE_IFDEF_END ')dnl

        

        _POP()')




Sorry, I was wrong. _MEMBER_SET(name, name, Glib::ustring, gchar*)
does generate the code you showed.
>> would generate that code. In this case a reference is OK, but it looks like the generated code can cause a memory leak. Who owns the duplicated string? Who deallocates it? What if gobj()->name contains a pointer to a string when set_name() is called?


Basically once again, return by value. What would be the correct wrap for the simple struct? Wrap struct and manually wrap set/get method?

I will investigate how private members are stored and how they related to the original C struct. Thanks

In Glib::OptionEntry, _MEMBER_SET is not used for strings. Those methods are hand-coded to avoid a memory leak. Example:

   void OptionEntry::set_long_name(const Glib::ustring& value)
   {
      if (gobject_->long_name)
      {
        g_free((gchar*)(gobject_->long_name));
        gobject_->long_name = nullptr;
      }

      gobj()->long_name = (value).c_str() ? g_strdup((value).c_str()) :
   nullptr;
   }


Don't ask me why value.c_str() is tested for nullptr. I don't understand. I don't think it can ever be a nullptr. And even if it is, g_strdup() can handle that.


-Pavlo Solntsev


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