⚠️ DEPRECATED

This gem is no longer maintained. Ruby’s modern caller_locations builtin (added in 2.0) covers most use cases.

better_caller

Author	Tim Morgan
Date	Dec 23, 2009
License	MIT (see `LICENSE.txt` for details)

Introduction by example

Actions speak louder than words. Gone are the days of this old suckageness:


caller #=> ["test.rb:8:in `foo'", "test.rb:16:in `<main>'"]

With better_caller, you get this new hotness:


require 'better_caller'
better_caller #=> [["test.rb", 8, :foo, #<Binding:0x000001010cae50>], ["test.rb", 16, :"<main>", #<Binding:0x000001010caef8>]]

There are a couple of things you may notice. First of all, the okay-that’s-nice thing: String parsing is a thing of the past. You get the file, line, and method as separate elements. This happens at the Ruby interpreter level.

Now, the holy-shit-that’s-awesome feature: You get bindings, all the way up the stack. Yes, that’s right, you can do this:


eval "local_variables", better_caller.first.last #=> [ :var1, :var2, :foo ]

You also get this stuff in exception, mondo excellent for debugging:


$!.better_backtrace # now you can figure out what your local variables were at the time of the exception!

This is horribly slow, right? You’re using some `set_trace_func` magic that’s going to make my Ruby 1,000,000% slower, right?

No. better_caller is a C function that uses the internal Ruby memory structures to build its output. Absolutely no set_trace_func and no speed hit.

Super ominous alpha warning

better_caller is extremely, hyperbolically alpha right now. Here are some known obstacles currently preventing it from blowing minds:

It only works with a very specific version of Ruby (in particular, 1.9.2-p136). This is because it uses some private Ruby C functions to work its magic, so it keeps a copy of some header files that you’re not really supposed to be using.
Storing local variables in exceptions isn’t quite working yet. Hopefully I’ll have a fix soon; be patient.

Despite that, it does work sometimes, and when it does, I think it rocks. If you do too, please do me the honor of contributing to this project, especially if you’re one of the three people on the planet that understand the workings of Ruby frame pointers. That would be swell.

Additional to-do items