From: Its Me <itsme213@...>
Date: 2004-04-08T04:09:19+09:00
Subject: Re: Simplified GTK

I love it!

Here with several (imo) improvements:
1. use dyamically scoped variables (really appropriate)
2. can use 1. to set up any overridable defaults e.g.
    with_context(:VBox=>{:direction=>:top_down}) { ... }
    find_in_context [:VBox, :direction]
3. return handles to widgets
4. can add widgets "after the fact"
5. can add externally created widget instances

########################

# Begin code
require 'gtk2'

class Gtk::Window
  def add_child c
    self.add c
  end
end

class Gtk::HBox
  def add_child c
    self.pack_start c
  end
end

class Gtk::VBox
  def add_child c
    self.pack_start c
  end
end

# BEGIN: dynamically scoped variables
  # Modified version of Avi Bryant's code
  # Can lookup a symbol OR a path (list of symbols)
  # Used for widget's :parent, can be used for all GTK defaults
def with_context(params)
  k, name = catch(:context) {yield; return}
  k.call(lookup(params,name) || find_in_context(name))
end

def find_in_context(name)
  callcc{|k| throw(:context, [k, name])}
end

def lookup(params, name)
  return params[name] if name.is_a? Symbol
  if name.is_a? Array
    name.each do |n| params = params[n] end
    return params
  end
  throw :Wrong_type
end
# END: dynamically scoped variables

p lookup ( {:a=>{:b=>{:c=>3}}}, [:a, :b] )

class EzGtkWindow
  # could easily set up defaults for all widget configuration
  # use dynamically scoped variables for easy temporary overriding
  def main
    window = Gtk::Window.new
    with_context(:parent=>window) { yield }
    window
  end
  def hbox
    hbox = Gtk::HBox.new(false)
    parent = find_in_context(:parent)
    parent.add_child(hbox)
    with_context(:parent=>hbox) { yield }
    hbox
  end
  def vbox
    vbox = Gtk::VBox.new(false)
    parent = find_in_context(:parent)
    parent.add_child(vbox)
    with_context(:parent=>vbox) { yield }
    vbox
  end
  def button(string, &block)
    button = Gtk::Button.new(string)
    button.signal_connect("clicked", block)
    parent = find_in_context(:parent)
    parent.add_child(button)
    button
  end
  def external(widget)
    find_in_context(:parent).add_child(widget)
  end
end

class MyWindow < EzGtkWindow
  def initialize
    @m = main {
      @hb = hbox {
        @vb = vbox {
          @b1 = button("Do it") { puts "pressed btn1"; $stdout.flush }
          @b2 = button("This too") { puts "pressed btn2"; $stdout.flush }
        }
        @vb2 = vbox {
          @b3 = button("Quit") { puts Gtk.main_quit; $stdout.flush }
        }
      }
    }

    with_context (:parent=>@vb2) {
      @b4 = button("Added later") { puts "Added later"; $stdout.flush }
    }

    @external = Gtk::Button.new("Externally Created")
    with_context (:parent=>@vb2) {
      external(@external)
    }

    [@m, @hb, @b1, @b2, @vb2, @b3, @b4, @external].each { |w| p w.class }
    @m.show_all
  end
end

Gtk.init
c = MyWindow.new
Gtk.main

# End code