From: mame@...
Date: 2018-08-17T14:41:15+00:00
Subject: [ruby-core:88515] [CommonRuby Feature#8661] Add option to print backstrace in reverse order(stack frames first & error last)

Issue #8661 has been updated by mame (Yusuke Endoh).


Over one year has passed since the backtrace order was reversed.  But I'm not still used to the new order.

I agree with Samuel's points.  In addition, the old order was more useful because it shows the last debug output and the exception message in one place.

```
$ ruby24 test.rb
...
...
"debug print"
"debug print"
"the last debug print"
test.rb:X:in 'buggy_func': exception message
	from test.rb:X:in `foo'
	from test.rb:X:in `bar'
...
...
```

In the above output, `"the last debug output"` and `test.rb:X:in 'buggy_func': exception message` are placed in one place.  It is easy to understand the situation and to start debugging.

However, the current behavior separates the two.  This is very frastrating.

```
$ ruby25 test.rb
...
...
"debug print"
"debug print"
"the last debug print"
...
...
	from test.rb:X:in `bar'
	from test.rb:X:in `foo'
test.rb:X:in 'buggy_func': exception message
```

Is there any change to revert the change?

----------------------------------------
Feature #8661: Add option to print backstrace in reverse order(stack frames first & error last)
https://bugs.ruby-lang.org/issues/8661#change-73573

* Author: gary4gar (Gaurish Sharma)
* Status: Closed
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
* Target version: 
----------------------------------------
Currently the way ruby prints the backtrace is that the error comes first & then the stack frames. like this

```
  Main Error Message
stack frame 1
stack frame 2
stack frame 3
.....
```

 this is perfectly fine provided

1. Backstraces are short, so fits in terminal.hence, no need to scroll.
2. you read it from top to bottom.


But, I am a rails developer where 

1. Backstraces are always HUGE, therefore seldom don't fit in terminal. Means LOTS of scrolling to do everytime we get an error.
2. in terminal we tend to read backstraces from bottom to top, especially when tailing(tail -f) the production logs. 
3. people, who practice Test-driven development literally spend most of their time scrolling to read backstraces to the point most end up buying a larger display.

Proposed Solution:
 Please add a way so we can configure backstraces to be printed in reverse order. so if you are reading from bottom, say from terminal, you can get the main error message without need to scroll. like this


```
stack frame 3
stack frame 2
stack frame 1
 Main Error Message
..... 
```

this would save lot of time because when the error message is print at the bottom, no need to scroll for reading it. Not sure if this can be done today. I tried Overriding Exception#backtrace but it caused stack level too deep & illegal hardware instruction Error.

Attached are currently what backstrace currently looks like & how there be an option to make it look for comparison.

---Files--------------------------------
current.log (5.13 KB)
proposed.log (4.9 KB)


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