hadley/evaluate — pull request #26 by yihui (2013-01-20 08:39:28+00:00)
Title: a bug in pv$visible

In `evaluate_call()`, `pv` might be an error object when an error occurs in `withVisible(output_handler$value(ev$value))`, which will in turn trigger this error when we use `pv$visible`:

```
Error in x$visible : $ operator is invalid for atomic vectors
```

A test case has been provided.

I hope the new version can be released as soon as possible, because this bug is pretty annoying. Thanks!