On 7/6/11 10:13 PM, Cameron McCormack wrote:
Hi Arun,
Adrian Bateman:
The spec doesn't seem to state this explicitly and I can't tell if
there is supposed to be an implicit requirement from WebIDL. Perhaps
the expectation is that this falls into the error condition and
should set readyState to DONE, result to null, and process the error
steps? Any thoughts?
Arun Ranganathan:
My thoughts are that this should be an OperationNotAllowedException,
and that this should be better defined.
IMHO WebIDL doesn't touch on what happens when a method within a
given API is called with null, so I think you're right to point this
issue out (thanks!).
There was a recent change in Web IDL which made interface types (like
the readAsXXX argument types) not include null by default, and if you
want to allow null, to write it as “Type?”. If you don’t change the
type in the File API spec to include the question mark, then Web IDL
defines it so that passing null means a TypeError will be thrown.
If you want to do some additional processing beyond throwing an
exception (e.g. setting readyState), then you would need to allow null
by using “Blob?” as the type and then say what happens when null is
passed in.
Wow, not only do I stand corrected, but I'm also gladdened :) This
change to WebIDL is a good one, and I'm sorry I missed it when it came out.
Adrian: this should answer your original question, although I still
think that in general, user agents differ pretty substantially over the
type of exceptions that are being thrown (and this is yet another
example). Hopefully this is something we can fix with updates.
-- A*
