[ruby-talk:21828] Re: ruby-gtk and entry validation

On Friday 21 September 2001 04:25 pm, Neil Conway wrote:
> Hi,
>
> On Thu, 2001-09-20 at 19:24, Ned Konz wrote:
> > The Gtk FAQ has an example of validating a Gtk::Entry field using an
> > insert_text handler:
> >
> > [snip C code]
> >
> > The problem is that I can't find any way in ruby-gtk to do this. There is
> > signal_handler_unblock in Gtk::Object but not
> > signal_handler_unblock_by_func().
>
> Okay, the reason you can't find those functions is because they're not
> implemented ;-)
>
> It's a bit difficult to implement them properly because of the way that
> signal handlers are implemented in Ruby/GTK: as (anonymous) blocks. This
> is convenient, but it means that the programmer can't refer back to the
> signal handler by name. I'm still thinking about how to do this. For
> now, here's a simple work-around: signal_connect returns the connection
> ID of the newly created signal handler. Then you can use the Gtk::Object
> methods signal_handler_block() and signal_handler_unblock(), which take
> the connection ID. I haven't tested it but AFAICT it should work.
>
> In the upcoming Ruby-GNOME 0.26, the missing functions will at least
> call rb_notimplement() and bail out; if anyone can think of a way to
> implement these functions nicely, let me know.

Well, in this instance, all that's needed is a way to execute a block from 
the inside of a signal handler without causing recursion; that is, to 
temporarily disable that signal handler.

If you could make method that would take a block and execute it with the 
current signal handler disabled (and/or perhaps with a different handler in 
scope), that would be useful for this idiom.

So an example of entry validation could look something like this (set up for 
Glade):

def insert_text_handler(entry, *a)
    entry.signal_handler_block_while {
        entry.insert_text(a[0].gsub(/\D/, ''))
    }
end

An example of using a different handler:

def insert_text_handler(entry, *a)
    entry.signal_handler_block_while(&other_handler) {
        entry.insert_text(a[0].gsub(/\D/, ''))
    }
end

-- 
Ned Konz
currently: Stanwood, WA
email:     [e-mail]
homepage:  http://bike-nomad.com