All my examples are pure C, which get a little more convenient if you're doing it with C++.

nice read.
Thanks a lot!

I have the following roadmap on the module.

• Initially all objects were refs to scalars, now they are refs to array (for the sake of efficiency), probably they will be hash refs in future, if more flexibility will be needed
• implement more widgets and their methods
• typemaps are planned, and this is my next step. Your writing will make this step easier, thanks:)
• Honestly, your idea about magic is fresh for me. I used magic some 25 years ago, it was nice and fun experience.
  I will sleep with this idea and - who knows - either switch to magic or otherwise will stand with blessed references.
  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?
• I don't affraid of users shooting themselves into the foot. After the damage they will fortunately survive and learn better :)
  Maybe I could write another user-safe wrapper module, around this thinner one, if there will be a request for that :)

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) {
  ...
}
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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");
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later in TVision.xs

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

NERDVANA this is absolutely fantastic and fills a gap or two. Thanks!

That was really good! It partly answers a nagging question I had after doing those speed comparisons between your Math::3Space vector calculations and doing it in PDL, which is still a bit slow in transitioning between Perl-land and C-land. One thing I know, thanks to using cachegrind, is that looking up a PDL object's pdl* spends a lot of time in hv_common, from sv_derived_from via isa_lookup, as called by the typemap-used pdl_SvPDLV.

In your opinion, would using this Perl magic scheme be quicker? And if so, does any hero feel like PR-ing (or just commenting some part-way code on https://github.com/PDLPorters/pdl/issues/451, the PDL performance issue) to make PDL-pointer-getting go quicker? (That issue has my previous research that found the hv_common stuff, and also links to the Math::3Space discussion issue)

Yes I think there are some speedups to be had using Magic for this code, but it's dealing with an awful lot of special cases, so hard to say exactly what the best change would be. I'll leave comments on the issue since it's sort of offtopic for this thread.

NERDVANA Thank you for that.

I have some advice for the XS... but too much advice for here. I might write a blog post...

SETEdit looks nice :)
thanks for the link to it

vkon, that was a lot of fun. On Linux, I had to build tvision as a shared library. After that, I modified one line in the Makefile.PL and was able to build perl-tvision plus run the demo. Very cool.

https://github.com/magiblot/tvision/issues/161

tvision patch to build a shared library

fantasic!
So you've managed tvision to run on termux and provided a fix for it?

Cool!

Thanks! )

Perl TVision installation on Linux

The C library build requirements are "libncursesw" (note the 'w') and "libgpm" for mouse support. Install dev/devel packages if packaged separately i.e. on Debian, Fedora, and Ubuntu.

# On Arch Linux
sudo pacman -S ncurses gpm
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The Perl module build requires "Text::Template" to make "TVision-methods.xs" and "typemap". Install manually if missing.

# On Arch Linux
sudo pacman -S perl-text-template
# or via CPAN
sudo cpanm -n Text::Template
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From the Turbo Vision README, the runtime requirements are "xsel" or "xclip" for clipboard support in X11 or "wl-clipboard" in Wayland environments.

# On Arch Linux
sudo pacman -S xsel          # X11
sudo pacman -S wl-clipboard  # Wayland
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Build the "Turbo Vision" C shared library

This requires a line change in "source/CMakeLists.txt" or the Perl module will fail due to missing shared library.

git clone --depth=1 https://github.com/magiblot/tvision
cd tvision

sed -i 's! STATIC ! SHARED !g' source/CMakeLists.txt
cmake . -B ./build -DCMAKE_BUILD_TYPE=Release
cmake --build ./build

sudo cmake --install ./build
cd ..
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Build the "TVision" Perl module

The GCC "-fpermissive" option is needed or the compiler will exit due to type mismatch.

Ignore the MANIFEST missing warnings. It assumes having "tvision.git" in this folder.

git clone --depth=1 https://github.com/vadrerko/perl-tvision
cd perl-tvision

X_CFLAGS="-I/usr/local/include -fpermissive -fPIC"
X_LDFLAGS="-L/usr/local/lib -ltvision -lncursesw -lgpm"

perl Makefile.PL --cflags="$X_CFLAGS" --ldflags="$X_LDFLAGS"

make TVision-methods.xs
make typemap
make
make test

perl -Iblib/arch -Iblib/lib t/f.t
perl -Iblib/arch -Iblib/lib demo/forms.pl
perl -Iblib/arch -Iblib/lib demo/tdialog.pl

sudo make install
cd ..
[download]

This worked for me on Arch-based Linux distro.