Issue #10561 has been updated by Yorick Peterse.


Benoit: correct, I just found this out by messing around more with this. This
behaviour is extremely confusing, especially since the tests both just compare
if `path` and `absolute_path` equal `__FILE__`.

Perhaps the Tempfile code in the tests (https://github.com/ruby/ruby/blob/69be3620302aab57c43014aca08629c9d7b7ce44/test/ruby/test_backtrace.rb#L170)
checks for this, but it too is very confusing to understand. In case of Rubinius
I'll see if we even have a way of detecting if something is called from the main
script, and _again_ adjust our specs and implementation.

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Bug #10561: Improve function of Thread::Backtrace::Location #path and #absolute_path
https://bugs.ruby-lang.org/issues/10561#change-51409

* Author: Sam Saffron
* Status: Open
* Priority: Normal
* Assignee: 
* ruby -v: 2.2.0
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
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I was working on this issue in Rails and hit an area where Backtrace Location can be improved

https://github.com/rails/rails/pull/17782


1. It is undefined in the documentation how #absolute_path should operate when #path is invalid (in case of instance eval)
2. There are a few conditions where #path and #absolute_path can return nil, this forces extra protection code when parsing paths to check for nil. (for example getting filename)  

Suggestions:

1. Instead of returning Qnil from location_path and location_absolute_path on invalid conditions, return the string "(unknown)" which is easier to parse and sticks out better in a big backtrace. There is precedent here with the string "(eval)"
2. If path is invalid have absolute_path return "(unknown)", define that in the documentation
3. (possible) add an additional method on caller_location called #filename so people stop parsing filename from #path and #absolute_path
4. Evaluate if it makes sense to have #path and #absolute_path in the API as both methods can return full paths so the semantic difference is subtle. 



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