From: Daniel Finnie <danfinnie@...>
Date: 2007-01-14T07:40:49+09:00
Subject: Re: return_on

I have made the most hackish thing to accomplish this.  It is basically 
a regexp-supporting preprocessor.  I don't recommend using it.

#! /usr/bin/ruby -w

def preprocessor_define(*args, &blk)
	# Determine line of caller
	callerLine = caller.join.match(/[0-9]+/)[0].to_i
	
	# Get the source of the running file
	source = IO.read(__FILE__)
	
	# Remove the callerLine line
	source = source.split("\n")
	source.delete_at(callerLine - 1)
	source = source.join("\n")
	
	# Do the replacement
	source.gsub!(*args, &blk)
	
	# Avoid function redefinition warnings
	newName = ""
	50.times {newName << (rand(26) + 65).chr }
	source.gsub!("preprocessor_define", newName)
	
	# Run the replacement
	#puts source
	eval source
	exit
end

preprocessor_define(/return_on (.*)/) {|s| "return #{s[1]} unless 
#{s[1]}.nil?"}

def test
	zulu = 5
	return_on zulu
	puts "Broken."
end
test

Output: None, as 'puts Broken' never gets executed.

Trans wrote:
> Sometimes i do this:
> 
>   return x if x
> 
> Anyway to code it as:
> 
>   return_on x
> 
> t.
> 
> 
>