Empty xpath nodelist raises foreach error.

When using foreach() with an xpath query, if the xpath result is an empty
set, then foreach raises a 'Warning:  Invalid argument supplied for
foreach()' message. This should not really be raised, as (for foreach())
the xpath return should be a valid (but empty) 

Would it be possible to return an empty array/iterator/object just to
foreach() so that this message is not raised? (I think w3c says return
null, but they probably weren't considering foreach():) 

Otherwise you end up either doing two xpath queries (one to check there is a
result, and another to do the processing without a warning) or assigning
the xpath result to a temporary var and checking that before use (yeuch!).

Philip