From: Holden Glova <dsafari@...>
Date: 2000-12-30T08:04:30+09:00
Subject: [ruby-talk:8309] Re: use of backquotes

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On Sat, 30 Dec 2000 00:43, I think David Alan Black wrote:
> Hello --
>
> On Fri, 29 Dec 2000, Holden Glova wrote:
> > Hi all,
> >
> > Can anyone explain why I am getting a nil return value from this? I am
> > using backquotes to invoke another Ruby interpreter within the existing
> > interpreter against a specific source file. Here is the class that I am
> > trying to run from the sub-ruby interpreter.
> >
> > class Useless
> >
> >   def meth
> >     puts "Useless method in a useless class"
> >   end
> >
> > end
> >
> > u = Useless.new()
> > u.meth()
> >
> > Here is the output when run at the command line:
> > synack@eugene:~/ruby/rubyide$ ruby -w useless.rb
> > Useless method in a useless class
> >
> > Now - when I invoke useless.rb through another class through the use of
> > backquotes the result is nil.
> >
> > class RuntimeInterpreter
> >
> >   def invoke(file)
> >     `ruby -w #{file} 2>&1`.chomp!
> >   end
> >
> > end
>
> I'm not clear what you mean by result and/or return value.  The
> runtime output of Useless#meth?  and/or the exit status of useless.rb
> (as reflect in $?)?  I can get at both, so I can't duplicate your
> problem if it's one of those:
>
>    r = RuntimeInterpreter.new
>    s = r.invoke("useless.rb")
>    p s  # => "Useless method in a useless class"
>    p $? # => 0
>
>
> David

OK David - you are correct it works fine like that (I didn't think it would 
because it wasn't working within my tests), but when i run it through my 
tests I still get a nil value. What I mean by the result and/or return value 
is the runtime output of Useless#meth.  Here is the code that I run within 
RUnit to test this.

require 'runit/testcase'
 
 
require 'runtimeInterpreter'
 
class Test_RuntimeInterpreter < RUNIT::TestCase
 
  def testInvoke
    interpreter = RuntimeInterpreter.new()
    result = interpreter.invoke("../useless.rb")
 
    p result	# ---> nil
    assert(result == "Useless method in a useless class")
  end
 
end


Does this make any sense? I'm confused even more now that David has pointed 
out that it works fine if I don't run it through my testing suite.

- -- 
Signed,
Holden Glova
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