From: Lloyd Zusman <ljz@...>
Date: 2008-02-13T01:47:02+09:00
Subject: Re: Proper way to allow Control-C to interrupt IO#gets

I left out a "Kernel.exit(0)" call in my test, but I still have the same
problemL

  trap("INT") do
    puts "got signal INT"
    Kernel.exit(0)
  end
  puts "Enter some characters followed by newline:"
  result = gets
  puts result

  % ruby cctest
  Enter some characters followed by newline:
  [ here I enter AB^CDEFG, where "^C" is Control-C, which
    doesn't cause the input to be aborted ]
  ABDEFG           <-  This is what echos when I'm typing.
  got signal INT   <-  This is what echos after I hit newline.

In other words, the SIGINT still doesn't get processed until
after the newline is entered.


Lloyd Zusman <ljz@asfast.com> writes:

> What is the canonical method for allowing an IO#gets call to be
> immediately interrupted by Control-C?  This doesn't seem to work as I am
> expecting.  Consider the following bit of ruby code:
>
>   trap("INT") do
>     puts "got signal INT"
>   end
>   puts "Enter some characters followed by newline:"
>   result = gets
>   puts result
>
> When I run this and enter a few characters interspersed with an instance
> of Control-C, the Control-C doesn't get recognized until after I hit
> newline.  Assuming that this program is in a file called "cctest",
> here's what happens:
>
>   % ruby cctest
>   Enter some characters followed by newline:
>   [ here I enter AB^CDEFG, where "^C" is Control-C, which
>     doesn't cause the input to be aborted ]
>   ABDEFG           <-  This is what echos when I'm typing.
>   got signal INT   <-  This is what echos after I hit newline,
>   DEFG             <-  ... and this, as well.
>
> In other words, the SIGINT resulting from Control-C doesn't get
> processed at until after I type the newline.
>
> I've searched for discussions of this on the net, but I haven't found
> anything under a "ruby interrupt gets" Google search, because the word
> "gets" is used so commonly in English in so many other contexts.
>
> I know that I can write my own input handler or use something like the
> HighLine package, but I'm wondering whether there's a way to cause
> IO#gets to do what I want.
>
> By the way, in case this is pertinent ...
>
>   % ruby --version
>   ruby 1.8.5 (2006-12-25 patchlevel 12) [i686-linux]
>
>   % uname -mor
>   2.6.9-022stab078.20-enterprise i686 GNU/Linux
>
> Thanks in advance.
>
>
> -- 
>  Lloyd Zusman
>  ljz@asfast.com
>  God bless you.
>
>
>

-- 
 Lloyd Zusman
 ljz@asfast.com
 God bless you.