[ruby-core:84701] [Ruby trunk Bug#14324] Should Exception#full_message include escape sequences?

Issue #14324 has been updated by Eregon (Benoit Daloze).


nobu (Nobuyoshi Nakada) wrote:
> Since `Exception#full_message` is expected to return the message printed to stderr, escape sequences are intentional.

But how to know if Exception#full_message is later used to print to $stderr, a log or something else?

Exception#backtrace for instance is the same on all Ruby implementations, even though the top-level handler might print differently.

I think having Exception#full_message be the canonical (no TTY, as in 2.4) representation of message+backtrace would make sense.
Reusing the new reversed MRI exception format here but only in some cases feels wrong.

I think libraries should do their own formatting if they want reversed exceptions.
It would be more portable and reliable.

How should other Ruby implementations behave here?
Print their own custom format by default? Is that good for usages of #full_backtrace?
Or try to mimic the new MRI reverse+highlight backtrace format?

> But I think it's wrong that there is no way to disable them now.
> 
> https://github.com/nobu/ruby/tree/bug/14324-full_message-options

Options seems a good idea.


----------------------------------------
Bug #14324: Should Exception#full_message include escape sequences?
https://bugs.ruby-lang.org/issues/14324#change-69421

* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
* Assignee: sorah (Sorah Fukumori)
* Target version: 2.6
* ruby -v: ruby 2.5.0p0 (2017-12-25 revision 61468) [x86_64-linux]
* Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN
----------------------------------------
```
$ ruby -e 'p RuntimeError.new("foo").full_message'
"\e[1mTraceback \e[m(most recent call last):\n-e:1:in `full_message': \e[1mfoo (\e[4;1mRuntimeError\e[m\e[1m)\n\e[m"
```

That is probably not intended.

```
$ ruby -e 'p RuntimeError.new("foo").full_message' |& cat
"-e:1:in `full_message': foo (RuntimeError)\n"
```

So `Exception#full_message` depends if stderr is a tty which seems wrong.
I think it should be the second result, i.e., no escape sequences.



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