colinta/SublimeFileDiffs — pull request #60 by burtbeckwith (2014-09-01 14:23:41+00:00)
Title: Bug fix for unnamed view

I was seeing a lot of these errors in ST3:

```
Traceback (most recent call last):
File "/opt/sublime_text_3_build_3065_x64/sublime_plugin.py", line 472, in is_visible_
raise ValueError("is_visible must return a bool", self)
ValueError: ('is_visible must return a bool', )
```

`file_name()` returns `None` for a new view that hasn't been saved yet and has no name, and apparently Python won't coerce that to boolean, so the return value type is wrong. Either wrapping in `bool( ... )` or using `self.view.file_name() is not None` both worked for me.