From: Joel VanderWerf <vjoel@...>
Date: 2008-03-15T15:53:33+09:00
Subject: Re: how to abruptly end a program?

Tom Cloyd wrote:
> Joel VanderWerf wrote:
>> Tom Cloyd wrote:
>>> I read in <Programming Ruby 2nd ed.> (p. 303) - ""If Ruby comes 
>>> across a line anywhere in the source containing just �_ _END_ _�, 
>>> with no leading or trailing whitespace, it treats that line as the 
>>> end of the program�any subsequent lines will not be treated as 
>>> program code."
>>>
>>> That's not what's happening for me. The following -
>>> _ _END_ _
>>> __END__
>>> _END_
>>>
>>> all produce the same result for me - "undefined local variable or 
>>> method"
>>> That DOES bring the program to an abrupt end, but its rather 
>>> ungraceful. Is this the intended result - a crash due to an 
>>> interpreter error?
>>
>> What the quote (a bit ambiguous perhaps) means is that the __END__ 
>> line and following lines are not treated as part of the program text. 
>> It has nothing to do with control flow. It's like comment block that 
>> runs to the end of the file without any explicit termination. (It's 
>> more than that because you can read it with DATA.)
>>
> OK, but couldn't ANY uninitialized variable achieve the same messy 
> result? What's the point? This surely can't be the intended result. 
> Makes no sense to me.

__END__ by itself on a line shouldn't exit the program. If you're 
getting that error, maybe there is an extra char on the line. A space 
perhaps?

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