1Tcl-perl(3)           User Contributed Perl Documentation          Tcl-perl(3)
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NAME

6       Tcl vs perl - very old suspect documentation on porting.
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DESCRIPTION

9       This isn't really a .pod yet, nor is it Tcl vs perl it is a copy of
10       John's comparison of Malcolm's original perl/Tk port with the current
11       one. It is also out-of-date in places.
12
13         From: john@WPI.EDU (John Stoffel )
14
15         Here are some thoughts on the new Tk extension and how I think the
16         organization of the commands looks.  Mostly, I'm happy with it, it
17         makes some things more organized and more consistent with tcl/tk, but
18         since the overlying language is so different, I don't think we need to
19         follow exactly the tcl/tk model for how to call the language.
20
21         The basic structure of the Tk program is:
22
23             require Tk;
24
25             $top = MainWindow->new();
26
27             #
28             # create widgets
29             #
30
31             Tk::MainLoop;
32
33             sub method1 {
34             }
35
36             sub methodN {
37             }
38
39         This is pretty much the same as tkperl5a5, with some cosmetic naming
40         changes, and some more useful command name and usage changes.  A quick
41         comparison in no particular order follows:
42
43         tkperl5a5                             Tk
44         -------------------------------       -----------------------------------
45         $top=tkinit(name,display,sync);       $top=MainWindow->new();
46
47         tkpack $w, ... ;              $w->pack(...)
48
49         $w = Class::new($top, ...);   $w = $top->Class(...);
50
51         tkmainloop;                   Tk::MainLoop;
52
53         tkbind($w,"<key>",sub);               $w->bind("<key>",sub);
54
55         tkdelete($w, ...);            $w->delete(...);
56
57         $w->scanmark(...);            $w->scan("mark", ...);
58
59         $w->scandragto(...);          $w->scan("dragto", ...);
60
61         $w->tkselect();                       $w->Select();
62
63         $w->selectadjust(...);                $w->selection("adjust", ...);
64
65         $w->selectto(...);            $w->selection("to", ...);
66
67         $w->selectfrom(...);          $w->selection("from", ...);
68
69         $w->tkindex(...);             $w->index(...);
70
71         tclcmd("xxx",...);              &Tk::xxx(...)    # all Tk commands, but no Tcl at all
72
73         tclcmd("winfo", xxx, $w, ...);  $w->xxx(...);
74
75                                       $w->mark(...);
76
77                                       $w->tag(...);
78
79         $w->grabstatus();             $w->grab("status");
80
81         $w->grabrelease(...);         $w->grab("release", ...);
82
83         focus($w);                    $w->focus;
84
85         update();                     Tk->update();
86
87         idletasks();                  Tk->update("idletasks");
88
89         wm("cmd",$w, ...);            $w->cmd(...);
90
91         destroy($w);                  $w->destroy();
92
93                                       Tk::option(...);
94                                         $w->OptionGet(name,Class)
95
96                                       $w->place(...)
97
98                                       Tk::property(...);
99
100         $w = Entry::new($parent,...)
101
102         is now
103
104         $w = $parent->Entry(...)
105
106         As this allows new to be inherited from a Window class.
107
108           -method=>x,-slave=>y
109
110          is now
111
112           -command => [x,y]
113
114         1st element of list is treated as "method" if y is an object reference.
115         (You can have -command => [a,b,c,d,e] too; b..e get passed as args).
116
117         Object references are now hashes rather than scalars and there
118         is only ever one such per window.  The Tcl_CmdInfo and PathName
119         are entries in the hash.
120
121         (This allows derived classes to
122         re-bless the hash and keep their on stuff in it too.)
123
124         Tk's "Tcl_Interp" is in fact a ref to "." window.
125         You can find all the Tk windows descended from it as their object
126         references get added (by PathName) into this hash.
127         $w->MainWindow returns this hash from any window.
128
129         I think that it should extend to multiple tkinits / Tk->news
130         with different Display's - if Tk code does.
131
132         Finally "bind" passes window as "extra" (or only)
133         argument. Thus
134
135         Tk::Button->bind(<Any-Enter>,"Enter");
136
137         Binds Enter events to Tk::Button::Enter by default
138         but gets called as $w->Enter so derived class of Button can just
139         define its own Enter method. &EvWref and associated globals and race
140         conditions are no longer needed.
141
142         One thing to beware of : commands bound to events with $widget->bind
143         follow same pattern, but get passed extra args :
144
145         $widget->bind(<Any-1>,[sub {print shift}, $one, $two ]);
146
147         When sub gets called it has :
148
149            $widget $one $two
150
151         passed.
152
153         1st extra arg is reference to the per-widget hash that serves as the
154         perl object for the widget.
155
156         Every time an XEvent a reference to a special class is placed
157         in the widget hash. It can be retrieved by $w->XEvent method.
158
159         The methods of the XEvent class are the
160         Tcl/Tk % special characters.
161
162         Thus:
163
164         $widget->bind(<Any-KeyPress>,
165                       sub {
166                        my $w = shift;
167                        my $e = $w->XEvent;
168                        print $w->PathName," ",$e->A," pressed ,$e->xy,"\n");
169                       });
170
171         XEvent->xy is a special case which returns "@" . $e->x . "," . $e->y
172         which is common in Text package.
173
174         Because of passing a blessed widget hash to "bound" subs they can be
175         bound to (possibly inherited) methods of the widget's class:
176
177         Class->bind(<Any-Down>,Down);
178
179         sub Class::Down
180         {
181          my $w = shift;
182          # handle down arrow
183         }
184
185         Also:
186
187         -command and friends can take a list the 1st element can be a ref to
188         as sub or a method name. Remaining elements are passed as args to the
189         sub at "invoke" time. Thus :
190
191         $b= $w->Button(blah blah, '-command' => [sub{print shift} , $fred ]);
192
193         Should do the trick, provided $fred is defined at time of button creation.
194
195         Thus 1st element of list is equivalent to Malcolm's -method and second
196         would be his -slave.  Any further elements are a bonus and avoid
197         having to pass ref to an array/hash as a slave.
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201perl v5.30.1                      2020-01-30                       Tcl-perl(3)