ruby-rdf/rdf — pull request #4 by mistydemeo (2012-10-01 19:21:51+00:00)
Title: Writer.buffer: raise if no block provided

RDF::Writer.buffer expects a block to be provided, but doesn't actually check whether it's there before trying to execute it. The resulting exception is pretty confusing to a user who might not realize they've done something wrong. I think it'd be better to check for a block first and raise an exception if none is provided. Compare:

```
NoMethodError: undefined method `call' for nil:NilClass
```

vs

```
ArgumentError: block expected
```