Now "TButton" is descendant of "TView" so it could use both TButton and TView methods because of @ISA - is the same possible in "magic" approach?

Multiple inheritance is an interesting situation! I think it should work... Your magic would be for type 'TObject*' (or a record with a TObject* field, since extra fields are almost always needed) and then you could use dynamic_cast to find out whether the method was being called on the correct type.

TVision.xs 

struct tvision_info {
  TObject *tobj;
};

struct tvision_info*
tvision_info_from_magic(SV *objref, int flags) {
  ...
}

[download]

typemap 

TYPEMAP
TObject*    O_TObject
TView*      O_TView
TButton*    O_TButton

INPUT
O_TObject
  $var= tvision_info_from_magic($arg, OR_DIE)->tobj;

O_TView
  $var= dynamic_cast<TView*>(tvision_info_from_magic($arg, OR_DIE)->to
+bj);
  if (!$var) croak("Not an instance of TView");

O_TButton
  $var= dynamic_cast<TButton*>(tvision_info_from_magic($arg, OR_DIE)->
+tobj);
  if (!$var) croak("Not an instance of TButton");

[download]

later in TVision.xs 

bool
focus(view)
  TView* view
  CODE:
    RETVAL= view->focus();
  OUTPUT:
    RETVAL

[download]

You might even be able to use a C++ template function to fetch the magic, but I've never tried that. (my C++ is rusty, don't expect this to work as-is) 

template <T> void tvision_obj_from_magic(T *dest, SV *objref, int flag
+s) {
  struct tvision_info* tinfo= tvision_info_from_magic(objref, flags);
  T typed= tinfo->tobj? dynamic_cast<T>(tinfo->tobj) : NULL;
  if ((flags & OR_DIE) && !typed) croak("Wrong type of object");
  *dest= typed;
}

[download]
O_TButton
  tvision_obj_from_magic(&$var, $arg, OR_DIE);

[download]
Update

There's no need for a C++ template here because Perl XS provides you a variable '$type'. 

TYPEMAP
TObject*    O_TObject
TView*      O_TObject
TButton*    O_TObject

INPUT
O_TObject
  $var= dynamic_cast<$type>(tvision_info_from_magic($arg, OR_DIE)->tob
+j);
  if (!$var) croak("Object is not a $type");

[download]

In reply to Re^6: Curses-based applications? by NERDVANA
in thread Curses-based applications? by sedusedan

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.