From: Sy Ali <sy1234@...>
Date: 2006-06-08T15:52:24+09:00
Subject: Re: pausing until a character is received

Just for kicks I tried to better understand what's going on with trap.
 Maybe I misunderstand what it's for, but it doesn't seem to work the
way I want.  I can't seem to properly trap based on the signal name,
and reading through some docs led me to this type of code:

Signal.trap(0, lambda { puts "interrupted.." ; exit })

Signal 0 seems to be a generic exit code.  I can list the signals with this:

Signal.list.each { |i|
	print i
	puts ""
}

but I don't know the correct signal to use.

Now I'm going to give up, not just because it's almost 3am but because
catching 3 from read_char does the job for me.  If/when I end up
working with signals I'll definitely need to revisit this stuff.

----

begin
	require "Win32API"
	def read_char
		Win32API.new("crtdll", "_getch", [], "L").Call
	end
rescue LoadError
	def read_char
		system "stty raw -echo"
		STDIN.getc
	ensure
		system "stty -raw echo"
	end
end

i = 1
until i > 3
	a = read_char
 	if a == 3 then puts "Interrupt received.  This shouldn't be
displayed.\n ... but it does." ; break ; end
	puts "I received:  " + a.to_s
	i += 1
end

puts "This shouldn't display upon interrupt."
puts " ... but it always displays"

Signal.trap(3, lambda { puts "interrupted.." ; exit })