comp.lang.ruby

Brian Schröder

4/29/2005 12:04:00 PM

On 29/04/05, Greg Millam <ruby-talk@lethalcode.net> wrote:
> In PageTemplate, a project of mine with Brian Wisti, we provide a
> framework of sorts that has a large number of layers between the call to
> PageTemplate.output, and a point where the user's own code is later called.
>
> If an error exists in the user's code, it looks somewhat like this:
>
> /home/walker/public_html/deafcode/rbsource/user_instance.rb:3:in
> `fullname': undefined local variable or method `last_nam' for
> #<User:0xb7b92e38> (NameError)
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/parser.rb:86:in `send'
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/parser.rb:86:in `get'
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/parser.rb:78:in `each'
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/parser.rb:78:in `get'
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/commands.rb:248:in `output'
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/commands.rb:145:in `output'
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/commands.rb:145:in `map'
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/commands.rb:145:in `output'
> ... 13 levels...
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/commands.rb:145:in `output'
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/commands.rb:187:in `output'
> from /home/walker/public_html/deafcode/rbsource/site.rb:90:in `output'
> from index.cgi:23
>
> About 23 levels of output of PageTemplate alone.
>
> What I'd like is to shorten that to one:
>
> /home/walker/public_html/deafcode/rbsource/user_instance.rb:3:in
> `fullname': undefined local variable or method `last_nam' for
> #<User:0xb7b92e38> (NameError)
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/commands.rb:187:in `output'
> from /home/walker/public_html/deafcode/rbsource/site.rb:90:in `output'
> from index.cgi:23
>
> Is there any safe way to do this?
>
> Alternately, I'd also like to potentially generate output like this:
>
> /home/walker/public_html/deafcode/rbsource/user_instance.rb:3:in
> `fullname': undefined local variable or method `last_nam' for
> #<User:0xb7b92e38> (NameError)
> from Template:user_profile.html in "Value: user.fullname"
> from Template:user_profile.html in "If: user"
> from Template:main_page.html in "Include user_profile.html"
> from Template:main_page.html in "Loop users: user"
> from /usr/lib/ruby/site_ruby/1.8/PageTemplate/commands.rb:187:in `output'
> from /home/walker/public_html/deafcode/rbsource/site.rb:90:in `output'
> from index.cgi:23
>
> Considerably more useful for the developer using PT.
>
> Is it possible to modify the backtrace like this?
>
> Thanks,
>
> - Greg
>
>

You could expand on this theme:

#!/usr/bin/ruby

def recurse(i)
raise "No more recursion please" if i == 0
recurse_a(i-1)
end

def recurse_a(i)
recurse(i)
end

begin
recurse(1000)
rescue => e
puts e.inspect
puts e.backtrace[0], '...', e.backtrace[-2..-1]
end

regards,

Brian

--
http://ruby.brian-sch...

multilingual _non rails_ ruby based vocabulary trainer:
http://www.vocabu... | http://www.g... | http://www.vok...