NAME

Tcl_vs_perl - very old suspect documentation on porting.

DESCRIPTION

This isn't really a .pod yet, nor is it Tcl vs perl it is a copy of John's comparison of Malcolm's original perl/Tk port with the current one. It is also out-of-date in places.

  From: [email protected] (John Stoffel )  Here are some thoughts on the new Tk extension and how I think the  organization of the commands looks.  Mostly, I'm happy with it, it  makes some things more organized and more consistent with tcl/tk, but  since the overlying language is so different, I don't think we need to  follow exactly the tcl/tk model for how to call the language.  The basic structure of the Tk program is:      require Tk;      $top = MainWindow->new();      #      # create widgets      #      Tk::MainLoop;      sub method1 {      }      sub methodN {      }  This is pretty much the same as tkperl5a5, with some cosmetic naming  changes, and some more useful command name and usage changes.  A quick  comparison in no particular order follows:  tkperl5a5                             Tk  -------------------------------       ----------------------------------  $top=tkinit(name,display,sync);       $top=MainWindow->new();  tkpack $w, ... ;              $w->pack(...)  $w = Class::new($top, ...);   $w = $top->Class(...);  tkmainloop;                   Tk::MainLoop;  tkbind($w,"<key>",sub);               $w->bind("<key>",sub);  tkdelete($w, ...);            $w->delete(...);  $w->scanmark(...);            $w->scan("mark", ...);  $w->scandragto(...);          $w->scan("dragto", ...);  $w->tkselect();                       $w->Select();  $w->selectadjust(...);                $w->selection("adjust", ...);  $w->selectto(...);            $w->selection("to", ...);  $w->selectfrom(...);          $w->selection("from", ...);  $w->tkindex(...);             $w->index(...);  tclcmd("xxx",...);              &Tk::xxx(...)    # all Tk commands, but no Tcl at all  tclcmd("winfo", xxx, $w, ...);  $w->xxx(...);                                $w->mark(...);                                $w->tag(...);  $w->grabstatus();             $w->grab("status");  $w->grabrelease(...);         $w->grab("release", ...);  focus($w);                    $w->focus;  update();                     Tk->update();  idletasks();                  Tk->update("idletasks");  wm("cmd",$w, ...);            $w->cmd(...);  destroy($w);                  $w->destroy();                                Tk::option(...);                                  $w->OptionGet(name,Class)                                $w->place(...)                                Tk::property(...);  $w = Entry::new($parent,...)  is now  $w = $parent->Entry(...)  As this allows new to be inherited from a Window class.    -method=>x,-slave=>y   is now    -command => [x,y]  1st element of list is treated as "method" if y is an object reference.  (You can have -command => [a,b,c,d,e] too; b..e get passed as args).  Object references are now hashes rather than scalars and there  is only ever one such per window.  The Tcl_CmdInfo and PathName  are entries in the hash.  (This allows derived classes to  re-bless the hash and keep their on stuff in it too.)  Tk's "Tcl_Interp" is in fact a ref to "." window.  You can find all the Tk windows descended from it as their object  references get added (by PathName) into this hash.  $w->MainWindow returns this hash from any window.  I think that it should extend to multiple tkinits / Tk->news  with different Display's - if Tk code does.  Finally "bind" passes window as "extra" (or only)  argument. Thus  Tk::Button->bind(<Any-Enter>,"Enter");  Binds Enter events to Tk::Button::Enter by default  but gets called as $w->Enter so derived class of Button can just  define its own Enter method. &EvWref and associated globals and race  conditions are no longer needed.  One thing to beware of : commands bound to events with $widget->bind  follow same pattern, but get passed extra args :  $widget->bind(<Any-1>,[sub {print shift}, $one, $two ]);  When sub gets called it has :     $widget $one $two  passed.  1st extra arg is reference to the per-widget hash that serves as the  perl object for the widget.  Every time an XEvent a reference to a special class is placed  in the widget hash. It can be retrieved by $w->XEvent method.  The methods of the XEvent class are the  Tcl/Tk % special characters.  Thus:  $widget->bind(<Any-KeyPress>,                sub {                 my $w = shift;                 my $e = $w->XEvent;                 print $w->PathName," ",$e->A," pressed ,$e->xy,"\n");                });  XEvent->xy is a special case which returns "@" . $e->x . "," . $e->y  which is common in Text package.  Because of passing a blessed widget hash to "bound" subs they can be  bound to (possibly inherited) methods of the widget's class:  Class->bind(<Any-Down>,Down);  sub Class::Down  {   my $w = shift;   # handle down arrow  }  Also:  -command and friends can take a list the 1st element can be a ref to  as sub or a method name. Remaining elements are passed as args to the  sub at "invoke" time. Thus :  $b= $w->Button(blah blah, '-command' => [sub{print shift} , $fred ]);  Should do the trick, provided $fred is defined at time of button creation.  Thus 1st element of list is equivalent to Malcolm's -method and second  would be his -slave.  Any further elements are a bonus and avoid  having to pass ref to an array/hash as a slave.