From: Joel VanderWerf <vjoel@...>
Date: 2007-04-06T04:05:08+09:00
Subject: Re: Rake and removing a capturing ^C

Scott Taylor wrote:
> 
> How can I remove such a trapping from a program?
> 
> I'm running autotest through a rake task.  Autotest uses ^C to restart 
> the tests, rake uses it to cancel the task at hand.
> 
> What would be the best way to remove this trap from rake?

I don't know if this will help without hacking into rake or autotest, 
but you can save and restore the handler. The return value of #trap is 
the previous handler, which is just a proc object:

irb(main):001:0> oldh = trap("INT") {puts "newh"}
=> #<Proc:0x02b2ac30@c:/ruby/lib/ruby/1.8/irb.rb:65>
irb(main):002:0>     ### <-- I pressed ^C and Enter here
newh
irb(main):003:0*
irb(main):004:0* newh = trap("INT", &oldh)
=> #<Proc:0x02e14428@(irb):1>
irb(main):005:0>
^C

There is also a useful special case. If you pass "DEFAULT" as the 
handler, you go back to ruby's default (which is different from irb's 
handler):

irb(main):001:0> trap("INT", "DEFAULT")
=> #<Proc:0x02b2ac30@c:/ruby/lib/ruby/1.8/irb.rb:65>
irb(main):002:0>     ### <-- I pressed ^C and Enter here
c:/ruby/lib/ruby/1.8/irb/input-method.rb:97:in `gets': Interrupt
         from c:/ruby/lib/ruby/1.8/irb.rb:132:in `eval_input'
         from c:/ruby/lib/ruby/1.8/irb.rb:259:in `signal_status'
         from c:/ruby/lib/ruby/1.8/irb.rb:131:in `eval_input'
         from c:/ruby/lib/ruby/1.8/irb/ruby-lex.rb:189:in `call'
         from c:/ruby/lib/ruby/1.8/irb/ruby-lex.rb:189:in `buf_input'
         from c:/ruby/lib/ruby/1.8/irb/ruby-lex.rb:104:in `getc'
         from c:/ruby/lib/ruby/1.8/irb/slex.rb:206:in `match_io'
         from c:/ruby/lib/ruby/1.8/irb/slex.rb:76:in `match'
          ... 8 levels...
         from c:/ruby/lib/ruby/1.8/irb.rb:70:in `start'
         from c:/ruby/lib/ruby/1.8/irb.rb:69:in `catch'
         from c:/ruby/lib/ruby/1.8/irb.rb:69:in `start'
         from c:/ruby/bin/irb.bat:20
Terminate batch job (Y/N)? y


-- 
        vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407