# \[ANN\] backtracer 0.5 -- get rid of ... 24 levels ... forever

**URL:** <https://www.ruby-forum.com/t/ann-backtracer-0-5-get-rid-of-24-levels-forever/178816>\
**Category:** Ruby\
**Created:** [November 11, 2009, 7:15pm UTC](https://www.ruby-forum.com/t/ann-backtracer-0-5-get-rid-of-24-levels-forever/178816 "2009-11-11T19:15:09Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![rogerdpack](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/45deac/32.png) [@rogerdpack](https://www.ruby-forum.com/u/rogerdpack)\
**Post date:** [November 11, 2009, 7:15pm UTC](https://www.ruby-forum.com/t/ann-backtracer-0-5-get-rid-of-24-levels-forever/178816/1 "2009-11-11T19:15:09Z")

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Pleased to announce the first public release of the backtracer gem (0.5)

It mission:  
to output higher quality backtraces if an unhandled exception occurs.

If you’ve ever seen  
…24 levels…  
and disliked it, this is the gem for you.

If you’ve ever wished the exception trace would display the code of each  
line (a la Python), this gem is also for you.

It displays the full back trace (no …'s), along with the code from  
each line! It can even display local variables at each level of the  
call stack, if desired.

Examples:

a script that once output:  
$ ruby crash.rb  
crash.rb:2:in `go2': unhandled exception from crash.rb:6:in `go’  
from crash.rb:9

Now outputs:

$ backtracer crash.rb

RuntimeError  
crash.rb:2:in `go2' raise crash.rb:7:in `go’  
go2(a, 55)  
crash.rb:10  
go ‘3’

(Now has the code lines, and if there had been …'s, would have ovecome  
them).

or use the --locals option

$ backtracer --locals crash.rb

unhandled exception: crash.rb:2: raise  
locals: {“a”=\>“3”, “b”=\>55}  
from:  
crash.rb:1 go2(a=\>3, b=\>55)  
locals: {“a”=\>“3”, “b”=\>55}  
crash.rb:5 go(a=\>3)  
locals: {“a”=\>“3”}

(displays locals, parameters as current value)

Also included are several other options. One is --ping, which  
periodically dumps current threads’ backtrace(s) (quite useful for  
profiling to see where you code is spending a lot of its time (thanks  
xray gem!)). There is also an option that will print out thread dumps  
whenever you hit ctrl+c.

To see all possible backtrace options run  
$ backtracer -h  
or  
$ backtracer --help

More examples can be found here:

> <https://github.com/rdp/backtracer/blob/master/examples/example_test_all_output>

> <https://github.com/rdp/backtracer/blob/master/examples/example_test_large_output>

> <https://github.com/rdp/backtracer/blob/master/examples/pinger_example>

== Installation ==

== 1.8.x ==

$ gem install ruby-debug # only necessary for the --locals option  
$ gem install jeweler && jeweler tumble # if necessary  
$ gem install backtracer

now run like

$ backtracer script\_name.rb  
$ backtracer --locals script\_name.rb arg1 arg2

== 1.9.1 ==

$ gem install ruby-debug19 # only necessary for the --locals option  
$ gem install jeweler && jeweler tumble # if necessary  
$ gem install backtracer

run as above (backtracer executable), or as a ruby require:  
$ ruby -rbacktracer script\_name  
$ ruby -rbacktracer\_locals script\_name

== Other ==

Note that you can load backtracing capability within a script itself by:

require ‘backtracer’

which will cause it to output a coded backtrace at exit time, if an  
unhandled exception occurs. Backtracer default and backtracer\_simple  
don’t cause runtime slowdown, so sometimes you just want to add this by  
default. If so, then add it to your RUBYOPT variable. (Once I did  
this, I wondered why I would ever want anything else). Here’s how:

1.9:

$ export RUBYOPT=-rbacktracer  
or  
$ export RUBYOPT=-rbacktracer\_simple # or whichever one you want

1.8:

you’ll need to install a helper gem since rubygems can’t load both  
itself and a gem on the command line for some reason.

$ sudo gem install faster\_rubygems # the helper–installs  
faster\_rubygems.rb and some other files to your site\_ruby dir  
$ export RUBYOPT=‘-rfaster\_rubygems -rbacktracer’  
or  
$ export RUBYOPT=‘-rfaster\_rubygems -rbacktracer\_simple’

Enjoy.

== Other related projects ==

unroller, [eigenclass.org](http://eigenclass.org/hiki/method+arguments+via+introspection),  
liveconsole, ruby-debug (thanks guys!)

Comments welcome.

> **[GitHub - rdp/backtracer: Quality output when an exception is thrown and not...](https://github.com/rdp/backtracer)**
>
> Quality output when an exception is thrown and not caught in Ruby - GitHub - rdp/backtracer: Quality output when an exception is thrown and not caught in Ruby

---

<div class="post-metadata">

**Author:** ![rogerdpack](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/45deac/32.png) [@rogerdpack](https://www.ruby-forum.com/u/rogerdpack)\
**Post date:** [November 12, 2009, 6:11pm UTC](https://www.ruby-forum.com/t/ann-backtracer-0-5-get-rid-of-24-levels-forever/178816/2 "2009-11-12T18:11:28Z")

</div>

> Pleased to announce the first public release of the backtracer gem (0.5)
> 
> It mission:  
> to output higher quality backtraces if an unhandled exception occurs.
> 
> If you’ve ever seen  
> …24 levels…  
> and disliked it, this is the gem for you.
> 
> If you’ve ever wished the exception trace would display the code of each  
> line (a la Python), this gem is also for you.

Thanks to aaalex for posting a screencast of backtracer:

[http://www.rubypulse.com/episode-0.18\_backtracer.html](http://www.rubypulse.com/episode-0.18_backtracer.html)  
Thanks!  
-r