sproutcore/sproutcore20 — comment on commit 58455866fa978b92035ac04d8cea1cc2dda84fb3
File:  line 0
By kselden:

No, the view helper has already appended options from the template to its view class, so the viewName is not in the attr arg which is additional props to add, the only thing that gets passed that way is template when you use a block helper.

You would need to do view.viewName not attr.viewName.

https://github.com/sproutcore/sproutcore20/blob/master/packages/sproutcore-handlebars/lib/helpers/view.js#L101-108