How do I add a C widget to Ruby/Tk?

ruby-talk
1

I have an existing Tcl/Tk widget written in C that I¹d like to port to
Ruby/Tk. The Lidie & Walsh book on Perl/Tk is helpful, but it doesn¹t quite
supply enough information. For example, it contains a call on
³Lang_CreateWidget² that needs to be mapped to something for Ruby/Tk, but
what might that be?

Does anyone have a working example of a C widget done in Ruby/Tk? Could you
please share the secrets?

Thanks,
Bill Paxton

2

Hi,

···

From: Bill Paxton <paxton@kitp.ucsb.edu>
Subject: how do I add a C widget to Ruby/Tk?
Date: Mon, 10 Jan 2005 02:33:05 +0900
Message-ID: <BE06AACA.1C67%paxton@kitp.ucsb.edu>

I have an existing Tcl/Tk widget written in C that I¹d like to port to
Ruby/Tk.

Please use your widget as it is.
Ruby/Tk (tcltklib) uses standard Tcl/Tk libraries.
If your wish (which uses same Tcl/Tk libraries) can load your widget
library, Ruby/Tk can load the widget library. For exapmle,

    <Ruby/Tk method call> <call on Tcl/Tk>
Tk.load_cmd_on_ip(tk_cmd) --> auto_load tk_cmd
Tk.load_tclscript(file, enc=nil) --> source ?-encoding enc? file
Tk.load_tcllibrary(file, pkg=None, --> load file ?pkg? ?interp?
                    interp=None)

Tk.tk_call(cmd, arg, ... ) --> cmd arg ...
Tk.ip_eval(script) --> (eval "script" on Tcl/Tk ip)

Probably, you'll be able to load your widget library by
Tk.load_tcllibrary('your widget library').
After that, you can create and control your widgets by Tk.tk_call().

If you want create a class for your widget,
it is better the class is a sub-class of TkWindow class.
When the create command of your widget is "xxx path ??-opt val? ...?",
minimum definition for your widget class is the following.
----------------------------------------------------------
  class YOUR_WIDGET < TkWindow
    TkCommandNames = ['xxx'.freeze].freeze

    WidgetClassName = 'Xxx' # if needed
    WidgetClassNames[WidgetClassName] = self # if needed

    # define instance methods for your widget class

  end
----------------------------------------------------------
Then, you'll be able to create your widget by
----------------------------------------------------------
  YOUR_WIDGET.new(parent, optkeys){ ... }
----------------------------------------------------------
like as other standard widgets.
--
Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)