From: Michael Garriss <mgarriss@...>
Date: 2003-09-14T02:19:13+09:00
Subject: Re: Counterpart of __LINE__ from C++ in Ruby?

RLMuller wrote:

> Hi All,
>  
> Does Ruby offer a global variable like $. or a global method that 
> provides the line-number in which it appears as opposed to the last 
> line scanned by Ruby?
>  
> I've assembled a large script of examples from various Ruby web 
> sites,  which in turn produces a lot of output.  It'd be nice if I 
> could just paste in puts "#{$something}" at various points so that a 
> reader perusing a portion of the output could easily locate the source 
> code that generated it.
>  
> It's no big deal.  Ruby seems to have everything in the world in it, 
> so I thought it might have this, too, though I couldn't find it.
>  
> Regards,
> Richard
>  
> A programmer is a device for turning coffee into code.
> Jeff Prosise (with an assist from Paul Erdos)



__LINE__  and __FILE__ work like expected in ruby.  You can also use 
Kernel#caller to find out where you came from.  This is useful you you 
want to write a function that will print where it was called from.   
This WON'T WORK:

# Hmmm.....it always prints '5'
def printline( linenum = __LINE__ )
  puts linenum
end

You have to use Kernel#caller and some regexping to do that (if anyone 
knows an easier way please tell me).

Michael