Re: [Vala] memory management class struct

["Martin (OpenGeoMap)" <martin opengeomap org>]

Thank you  so much Yu!!!



Yu Feng escribió:
> On Sat, 2008-08-23 at 10:00 -0300, Martin (OpenGeoMap) wrote:
>   
> > Hi:
> >
> > Someone know how c++ manage the member in classes. 
> >     
> You might want to read this.
> http://en.wikipedia.org/wiki/Virtual_table
>
> Look at the examples section. The vtable pointer in is similar to
> GTypeInstance member in GLib.
>
> I guess if there is no virtual member functions, there is no
> GTypeInstance alike field in C++(gcc at least)'s memory layout. I didn't
> find a ref source to support my assumptions.
>
> For your case if you don't use any features that requires a vtable, each
> of your lidar point object will use sizeof(GTypeInstance) less memory in
> g++ than in GLib. A overhead of around several mega bytes for GLib code.
>
> Yu
>   
> > I am asking this 
> > because in vala i know member funcions in classes are shared between all 
> > objects. This is important for me because if i want build engineering 
> > apps i use many entities of the same class. For example for the lidar 
> > point class i have to use 1 million of instances of the same class.
> >
> > I see blender is 100% C source code in the kernel, but for example K-3D 
> > is C++ pure code with extensive use of STL.
> > I know microstation kernel is C pure code because i have the header of 
> > all entities of the DGN format and itś only C structs.
> >
> > /* Our "Instance struct" defines all the data fields that make our object unique. */f 
> > typedef struct _SomeObject SomeObject;
> > struct _SomeObject
> > {
> >         GTypeInstance   gtype;
> >
> >         gint            m_a;
> >         gchar*          m_b;
> >         gfloat          m_c;
> > };
> >
> > /* Our "Class struct" defines all the method functions that our objects will share. */
> > typedef struct _SomeObjectClass SomeObjectClass;
> > struct _SomeObjectClass
> > {
> >         GTypeClass      gtypeclass;
> >
> >         void            (*method1)      (SomeObject *self, gint);
> >         void            (*method2)      (SomeObject *self, gchar*);
> > };
> >
> >
> >
> > Regards.
> >
> >
> > _______________________________________________
> > Vala-list mailing list
> > Vala-list gnome org
> > http://mail.gnome.org/mailman/listinfo/vala-list
> >     
>
>
>