From: Peter Bailey <pbailey@...>
Date: 2009-02-13T04:38:46+09:00
Subject: Error handling in Ruby scripts

Hi,
Can someone please help me with exception handling? I've written some
classes and scripts that I've used for a year or two. But now, I'm
having to use them with many thousands of files at once, and, even
though they process just one file at a time, there are sometimes errors
in the tools that I use. Specifically, I use an image processing tool
called Image Alchemy. In my Ruby scripts, I have a class written that
has in it various conversion routines where it converts the file pointed
to in Ruby to various formats--TIFF, PNG, etc., etc. My problem is that
when I'm presented with many thousands of files, I'm getting the odd
input file that's just bad. So, my Alchemy Ruby code fails, because
Alchemy itself is failing with that bad file. So, I've read a bit about
"raise," but, I can't seem to get it to work. Can I use "raise" as an
exception handler in my class? Then, in my scripts, could I use
"begin/rescue" with that exception?

Below is a subset of my class

Thanks,
Peter

class Alchemy
  def initialize(file)
   @file = file
  end
  def Alchemy.tiff(file)
   `alchemy #{file} -t1 -Zc1 -Zm2 -Za4 -Zd 300 300 .300 -o`
  end
  def Alchemy.tiffbw(file)
    `alchemy #{file} -t204 -Zc1 -Zm2 -Za4 -Zd 600 600 .300 -o`
  end
  def Alchemy.tiffgray(file)
    `alchemy #{file} -t1 -Zc1 -Zm2 -b -c256 -8 -Za4 -Zd 300 300 .300 -o`
  end
end
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