From: Tomas Na <krazz17@...>
Date: 2009-04-05T04:02:45+09:00
Subject: Function as Parameter?

I am new to Ruby so I don't know a great deal about the language, but
what I am trying to do is the following:
Create an application that will display a login form. The user enters
their details and then that form disappears and they are taken to a
different form containing a canvas (which will have images drawn on it
eventually).

I don't want to create both forms and set their visibility, as the
invisible form will still be loaded in memory which is a waste. They I
thought of getting around this is to start the program in a "form
manager" style class, which then has the ability to create either of the
two forms. The trouble I am facing then, is that the button the form has
to pass back the username and password to the form manager, so that when
the Login form closes it may construct a Canvas from and pass the
details.

To make this happen I figured I would pass in a callback. Searching
around, I couldn't find a lot of info about callbacks, but I was reading
about passing a symbol. I may have got this wrong, but it looks like if
I pass in :function_name then it will be a symbol that I can call.

Well I tried it like this:

def TestFunc()
  puts 'Test'
end

xaApp = FXApp.new
LoginForm.new(xaApp,'TestApp',:TestCallback)
xaApp.create
xaApp.run

In my "Form Manager", and in my LoginForm's initialize I have:
def initialize(anApp,sTitle,aCallback)
    super(anApp, sTitle,:opts => DECOR_ALL, :width => 165, :height =>
250)

    FXLabel.new(self,"Username:", nil, JUSTIFY_LEFT|LAYOUT_FILL_X)
    FXTextField.new(self, 23, nil, 0, TEXTFIELD_NORMAL)

    FXLabel.new(self,"Password:", nil, JUSTIFY_LEFT|LAYOUT_FILL_X)
    FXTextField.new(self, 23, nil, 0, TEXTFIELD_NORMAL)

    xbButton = FXButton.new(self,"Log in",:opts =>
FRAME_RAISED|LAYOUT_CENTER_X|LAYOUT_FIX_WIDTH|LAYOUT_FIX_HEIGHT,:width
=> 80, :height => 20)
    xbButton.connect(SEL_COMMAND,aCallback)
end

This runs okay until I click the button, at which point I get the error:
C:\Users\Tomas\Desktop\Ruby>ruby testapp.rb
c:/ruby/lib/ruby/gems/1.8/gems/fxruby-1.6.12-mswin32/lib/fox16/responder2.rb:55:
in `onHandleMsg': undefined method `call' for :TestCallback:Symbol
(NoMethodErro
r)
        from testapp.rb:14:in `run'
        from testapp.rb:14

If I can get this working, then I will be able to move on to trying to
get it working with passing the two string parameters in as well. Can
someone please explain to me how I can call the function in my main code
when the button is clicked in the form?
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