Re: [xsl] Signature of a function that may throw an error

["Christophe Marchand cmarchand@xxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

I have decided to re-write all the orchestrator, without Spring, without 
Zookeeper, without Redis, and with only 4 server instances instead of 12.

See you in Prague,
Christophe

Le 24/01/2019 C  00:47, Michael Kay mike@xxxxxxxxxxxx a C)critB :
>
>
>> On 23 Jan 2019, at 23:05, Christophe Marchand cmarchand@xxxxxxxxxx 
>> <mailto:cmarchand@xxxxxxxxxx> 
>> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx 
>> <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>> wrote:
>>
>> It has been very difficult to understand, and your help, especially 
>> on the code that may raise this error, help us a lot.
>>
>>
>
> Debugging XSLT can be very challenging. I'm working on a complex 
> stylesheet myself at the moment (more details, come to XML Prague) and 
> I've been trying to improve the diagnostics and debugging aids in the 
> product as I go.
>>
>> As a conclusion, this orchestrator is going to be re-written totally. 
>> Never trust a program made by a developer you can't trust !
>>
> Never hesitate to refactor code that's poorly structured, regardless 
> of who wrote it. Base your decisions on the code, not the author. The 
> best developers write bad code if their understanding of the 
> requirements was still evolving while they wrote it.
>
> Michael Kay
> Saxonica
>
>> Thanks a lot,
>> Christophe
>>
>> Le 22/01/2019 C  17:28, Michael Kay mike@xxxxxxxxxxxx a C)critB :
>>> The XPath spec defines the return type of the error() function as 
>>> "none", and the role of "none" in the type system is pretty much 
>>> unspecified. As a result, there was always a steady stream of 
>>> problems with edge cases in the W3C test suites in this area.
>>>
>>> Saxon actually implements the static return type of error() as 
>>> item(), which is intended to ensure that you won't get a static type 
>>> error from this sort of construct.
>>>
>>> This particular example doesn't seem to give a static error with 
>>> Saxon 9.9, though the error message looks like it comes from Saxon. 
>>> The code that produces this error is intended for the case where one 
>>> of the branches of the conditional always returns an empty sequence 
>>> (typically, an implicit xsl:otherwise).
>>>
>>> What software version are you running?
>>>
>>> Michael Kay
>>> Saxonica
>>>
>>>
>>>
>>>> On 22 Jan 2019, at 14:36, Christophe Marchand cmarchand@xxxxxxxxxx 
>>>> <mailto:cmarchand@xxxxxxxxxx> 
>>>> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx 
>>>> <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>> wrote:
>>>>
>>>> Hello,
>>>>
>>>> I have a function that must return a xs:string, or raise an error, 
>>>> if result value can not be computed, or is empty-sequence.
>>>>
>>>> Here is function :
>>>>
>>>> B  <xsl:function name="conf:getConfVar" as="xs:string">
>>>> B B B  <xsl:param name="conf" as="element(els-conf:conf)"/>
>>>> B B B  <xsl:param name="varName" as="xs:string"/>
>>>> B B B  <xsl:sequence select="
>>>> B B B B B  if (exists($conf/els-conf:variable[@name=$varName]))
>>>> B B B B B  then $conf/els-conf:variable[@name=$varName]/@value
>>>> B B B B B  else (
>>>> B B B B B B B  error(
>>>> B B B B B B B B B  $conf:ERROR_MISSING_ENTRY,
>>>> B B B B B B B B B  concat('Entry ',$varName,' is missing in environment 
>>>> configuration')
>>>> B B B B B B B  )
>>>> B B B B B  )
>>>> B B B B B  "/>
>>>> B  </xsl:function>
>>>>
>>>> When a variable does not exist in $conf, I expect an error being 
>>>> raised, and expect to catch it in a xsl:try / xsl:catch.
>>>>
>>>> But, in this case, I get this :
>>>>
>>>> XTTE0780: Conditional expression: The condition is not satisfied, 
>>>> so an empty sequence is returned, but this is not allowed as the 
>>>> result of call to conf:getConfVar
>>>> in xsl:sequence/@select ....
>>>>
>>>>   * I understand that error() function never return a value, so
>>>>     return value does not satisfies xsl:function/@as constrint. Is
>>>>     it correct ?
>>>>   * How could I write this, as I want the return type being
>>>>     xs:string, and not xs:string?, and I want my error to be raised
>>>>     when entry is missing ?
>>>>
>>>> Best regards,
>>>> Christophe
>>>>
>>>> XSL-List info and archive <http://www.mulberrytech.com/xsl/xsl-list>
>>>> EasyUnsubscribe 
>>>> <http://lists.mulberrytech.com/unsub/xsl-list/293509> (by email)
>>>
>>> XSL-List info and archive <http://www.mulberrytech.com/xsl/xsl-list>
>>> EasyUnsubscribe 
>>> <http://lists.mulberrytech.com/unsub/xsl-list/2837134> (by email)
>> XSL-List info and archive <http://www.mulberrytech.com/xsl/xsl-list>
>> EasyUnsubscribe <http://lists.mulberrytech.com/unsub/xsl-list/293509> 
>> (by email)
>
> XSL-List info and archive <http://www.mulberrytech.com/xsl/xsl-list>
> EasyUnsubscribe <http://lists.mulberrytech.com/unsub/xsl-list/2837134> 
> (by email <>)