[DPF] INVALID_ACCESS_ERR or NULL Section 4.3

Hi Jeremy,

This message contains a response to comments on

http://www.w3.org/TR/2004/WD-DPF-20041122/

s14.
item(335) INVALID_ACCESS_ERR or NULL

Section 4.3 declares an INVALID_ACCESS_ERR on the item() method,
but does not specify it's use. Rather the specification is to return
NULL. I suggest the specification should be changed to
throw an INVALID_ACCESS_ERR when the index is out of range.


The Item() method returns a DPFProperty within the property list  
based on an index (size of list) value. If an invalid index number is  
used, an INDEX_SIZE_ERR is raised. The INVALID_ACCESS_ERR is raised  
due to an invalid memory access that occurs after a DPFProperty was  
accessed from the list. For example, a script object would have  
accessed the value pointer of a DPFProperty node from the property  
list. Now the property was removed from the list. If the script  
object tries to access the value pointer (that was stored in the  
previous call), this exception would be raised. The DPFPropertyList  
always reflects the state of the properties within the list i.e they  
are live. If a property is removed from the system, the corresponding  
entry within the list points to an empty node.

-Keith Waters

Received on Friday, 3 June 2005 17:54:31 UTC