[ruby-core:104984] [Ruby master Feature#18083] Capture error in ensure block.

Issue #18083 has been updated by ioquatix (Samuel Williams).


Your proposed "shorter and easier to understand" implementation is actually incorrect:

```
def transaction1
  begin
    yield
  rescue Exception => error
  ensure
    if error
      puts "abort"
    else
      puts "commit"
    end
  end
end

def transaction2
  begin
    yield
  rescue Exception
    puts "abort"
  else
    puts "commit"
  end
end

catch(:foo) do
  transaction1 do
    throw :foo
  end
end
```

Try for `transaction1` and `transaction2`. The flow control is wrong for `transaction2`.

----------------------------------------
Feature #18083: Capture error in ensure block.
https://bugs.ruby-lang.org/issues/18083#change-93384

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
----------------------------------------
As discussed in https://bugs.ruby-lang.org/issues/15567 there are some tricky edge cases.

As a general model, something like the following would be incredibly useful:

``` ruby
begin
 ...
ensure => error
  pp "error occurred" if error
end
```

Currently you can get similar behaviour like this:

``` ruby
begin
  ...
rescue Exception => error
  raise
ensure
  pp "error occurred" if error
end
```

The limitation of this approach is it only works if you don't need any other `rescue` clause. Otherwise, it may not work as expected or require extra care. Also, Rubocop will complain about it.

Using `$!` can be buggy if you call some method from `rescue` or `ensure` clause, since it would be set already. It was discussed extensively in https://bugs.ruby-lang.org/issues/15567 if you want more details.



-- 
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