277475 - output w/ value attr broken when inside group or switch

Status: RESOLVED DUPLICATE of bug 265467

(Core Graveyard :: XForms, defect)

Description

[Darin Fisher]

output w/ value attr broken when inside group or switch

Comment 1

[Darin Fisher]

Attachment: v1 patch

Comment 2

[Allan Beaufour]

I'm not too happy with ignoring the return result, that sort of defies its
purpose. There is a problem, yes, but it lies somewhere else. I'd rather not see
this patch committed.

Comment 3

[Darin Fisher]

Allan: the point is that EvaluateNodeBinding throws an exception to indicate
that it cannot evalate the node binding (for whatever reason).  but, we don't
want to propagate that exception.  that is not an exception from the point of
view of our caller.  you seem to be proposing a change to EvaluateNodeBinding
such that it does not throw an exception in this case.  i agree, that would work
too, but then that would impact other callers of EvaluateNodeBinding who might
depend on that exception being thrown.

Comment 4

[Allan Beaufour]

(In reply to comment #3)
> you seem to be proposing a change to EvaluateNodeBinding
> such that it does not throw an exception in this case.  i agree, that would work
> too, but then that would impact other callers of EvaluateNodeBinding who might
> depend on that exception being thrown.

My opinion is that if an exception is thrown, it should not be ignored. The
other callers should be fixed then.

My ever-growing patch in bug 265467 has proper implementation and handling of
EvaluateNodeBinding().

Comment 5

[Darin Fisher]

> My opinion is that if an exception is thrown, it should not be ignored. The
> other callers should be fixed then.

In general, yes.. thrown exceptions should not be ignored.  But, we are not
really "ignoring" the exception here.  Instead, we are blanket catching all
exceptions and treating them as non-fatal errors.  In other words, the caller of
EvaluateNodeBinding knows that exceptions will be thrown when the element does
not have the required attributes to satisfy the EvaulateNodeBinding call.  But,
that is not an exceptional condition from the point of view of the <group> or
<repeat> element.  It has a code path it wants to take when those exceptions
occur.  So, it just turns out that "ignoring" the return value of
EvaluateNodeBinding yields that code path (and involves little code).

What I am doing effectively is making the GetContext method return NS_OK with a
NULL context out-param to specify that there is no context information.  That
seems better than adding checks to all of the callers to check for an exception.
 Then the caller only has to check the out-param to see if it is NULL.

NOTE: nsIXFormsContextControl::GetContext refers to the possibility of an empty
model ID being returned.  That seems consistent with the way I am changing the
implementation here.  The documentation also doesn't say anything about throwing
exceptions to indicate that there is no context.

Comment 6

[Darin Fisher]

fixed on XFORMS_20050106_BRANCH

Comment 7

[aaronr]

*** Bug 275105 has been marked as a duplicate of this bug. ***

Comment 8

[Allan Beaufour]

Fixed in bug 265467.

*** This bug has been marked as a duplicate of 265467 ***