Hi, I understand why the out params need to be something identifiable for S_FALSE, as we deal with this problem directly in Python with NVDA.
However, I'm lost as to why out params mean anything for any of the E_* error values. In Python's case, it will always raise an exception for any E_* value. In VB I would have thought it would do the same? Can someone please point out any languages that hide the hResult by returning out params, and don't differenciate between S_OK and S_FALSE, yet don't cause some kind of exception or major error for E_* values? If there is in deed languages that don't raise exceptions, then these changes are completely fine. If there are not, then when returning E_INVALIDARG it may not be necessary to mention what should happen to the out params. Certainly I agree with the changes to out params for better handling S_FALSE. Thanks Mick On 14/04/2010 5:24 PM, Alexander Surkov wrote: > Hi. Looks fine with me however I have a question. > >> 3) IAccessibleText::selection >> Change: >> To: >> S_FALSE if there is nothing to return, [out] values >> are -1s >> E_INVALIDARG if bad [in] passed, [out] values are > >> 5) IAccessibleHyperlink::anchor and IAccessibleHyperlink::anchorTarget >> Change: >> S_FALSE if there is nothing to return, [out] value >> is NULL >> E_INVALIDARG if bad [in] passed, [out] value is NULL >> To: >> S_FALSE if there is nothing to return, [out] value >> is a VARIANT with vt = VT_EMPTY >> E_INVALIDARG if bad [in] passed, [out] value is a >> VARIANT with vt = VT_EMPTY > > I confused by the difference between "nothing to return" and "bad [in] > passed". It sounds like "bad [in]" means "nothing to return" and vise > versa. > > Thank you. > Alex. > > > On Wed, Apr 14, 2010 at 5:54 AM, Pete Brunet<[email protected]> wrote: >> Please review the following... >> >> Thanks to Carolyn who is implementing IA2 in Eclipse I believe the following >> changes need to be made in next update to the spec. >> >> 1) IAccessibleHypertext::hyperlinkIndex >> Change: >> E_INVALIDARG if bad [in] passed, [out] value is NULL >> To: >> E_INVALIDARG if bad [in] passed, [out] value is -1 >> Because: >> Setting the pointer to NULL does not make sense in >> pass-by-reference world. >> >> 2) IAccessibleText::offsetAtPoint >> Change: >> E_INVALIDARG if bad [in] passed, [out] value is 0 >> To: >> E_INVALIDARG if bad [in] passed, [out] value is -1 >> Because: >> 0 is a valid value for the offset, and AT that cannot get >> the HRESULT will not be able to distinguish between S_OK and E_INVALIDARG. >> Add: >> S_FALSE if nothing to return, [out] value is -1 >> Because: >> The [in] values could all be valid, but x and y could >> specify a valid screen position but not one associated with a caret offset. >> >> 3) IAccessibleText::selection >> Change: >> S_FALSE if there is nothing to return, [out] values >> are 0s >> E_INVALIDARG if bad [in] passed, [out] values are 0s >> To: >> S_FALSE if there is nothing to return, [out] values >> are -1s >> E_INVALIDARG if bad [in] passed, [out] values are >> -1s >> Because: >> 0,0 is a valid value for the selection (i.e. the caret is >> before the first character), and AT that cannot get the HRESULT will not be >> able to distinguish between S_OK and S_FALSE/E_INVALIDARG. >> >> 4) IAccessible2::groupPosition >> Change: >> S_FALSE if no values are valid >> To: >> S_FALSE if no values are valid, [out] values are 0s >> Because: >> Although it can be determined from reading the parameter >> specs, this should probably be stated with the return value as well, for >> consistency and completeness. >> >> 5) IAccessibleHyperlink::anchor and IAccessibleHyperlink::anchorTarget >> Change: >> S_FALSE if there is nothing to return, [out] value >> is NULL >> E_INVALIDARG if bad [in] passed, [out] value is NULL >> To: >> S_FALSE if there is nothing to return, [out] value >> is a VARIANT with vt = VT_EMPTY >> E_INVALIDARG if bad [in] passed, [out] value is a >> VARIANT with vt = VT_EMPTY >> Because: >> The AT's will expect to see an "empty variant", not NULL. >> http://msdn.microsoft.com/en-us/library/dd373687(VS.85).aspx >> >> 6) IAccessibleValue::currentValue >> Change: >> S_FALSE if there is nothing to return, [out] value >> is NULL >> To: >> S_FALSE if there is nothing to return, [out] value >> is a VARIANT with vt = VT_EMPTY >> Because: >> The AT's will expect to see an "empty variant", not NULL. >> >> 7) IAccessibleValue::maximumValue and IAccessibleValue::minimumValue >> Add: >> S_FALSE if there is nothing to return, [out] value >> is a VARIANT with vt = VT_EMPTY >> Because: >> This should be consistent with >> IAccessibleValue::currentValue. >> >> Also modify the general note about variants slightly to mention VT_EMPTY: >> http://accessibility.linuxfoundation.org/a11yspecs/ia2/docs/html/_generalinfo.html#_variants >> >> 8) IAccessibleText::oldText and newText >> Change: >> S_FALSE if there is nothing to return, [out] value is >> NULL >> To: >> S_FALSE if there is nothing to return, the values of >> IA2TextSegment struct are set as follows: text = NULL, start = 0, end = 0. >> Because: >> Setting the [out] pointer to NULL does not make sense in >> pass-by-reference world. >> >> _______________________________________________ >> Accessibility-ia2 mailing list >> [email protected] >> https://lists.linux-foundation.org/mailman/listinfo/accessibility-ia2 >> >> > _______________________________________________ > Accessibility-ia2 mailing list > [email protected] > https://lists.linux-foundation.org/mailman/listinfo/accessibility-ia2 -- Michael Curran email/msn/jabber: [email protected] Skype/Twitter: md_curran _______________________________________________ Accessibility-ia2 mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/accessibility-ia2
