From: matt@... (matt neuburg)
Date: 2009-03-22T06:12:09+09:00
Subject: Re: how to know where ERB stopped?

Matthias Reitinger <reitinge@in.tum.de> wrote:

> matt neuburg wrote:
> > Let's say I've got an ERB template:
> > 
> > text1
> > <%= thing1() %>
> > text2
> > <%= thing2() %>
> > text3
> > <%= thing3() %>
> > text4
> > 
> > But let's say we get an error (exception) during the execution of
> > thing2(). How can I find out that this is where the error occurred? I
> > don't want to instrument thing1, thing2, thing3, etc; I'm hoping I can
> > just find out what ERB was doing when we errored out. Thx - m.
> 
> The following code illustrates how this could be accomplished (also 
> available as a pastie[1]):
> 
>   require 'erb'
> 
>   def thing1(); "foo" end
>   def thing2(); raise Exception.new("Something went wrong") end
>   def thing3(); "bar" end
> 
>   template = <<ERB
>     text1
>     <%= thing1() %>
>     text2
>     <%= thing2() %>
>     text3
>     <%= thing3() %>
>     text4
>   ERB
> 
>   erb = ERB.new(template)
> 
>   begin
>     erb.run
>   rescue Exception => e
>     puts "Exception: #{e}"
>     line = e.backtrace.grep(/^\(erb\)/)[0].split(':')[1].to_i
>     puts "While evaluating line #{line} of the template:"
>     puts template.split("\n")[line-1]
>     puts "Backtrace: ", e.backtrace
>   end
> 
> Hope that helps!

Very much so, thank you. Grepping and parsing the backtrace is the exact
clue that I needed. m.

-- 
matt neuburg, phd = matt@tidbits.com, http://www.tidbits.com/matt/
Leopard - http://www.takecontrolbooks.com/leopard-customizing.html
AppleScript - http://www.amazon.com/gp/product/0596102119
Read TidBITS! It's free and smart. http://www.tidbits.com