Re: [Xotcl] xotcl::nonposArgs

From: Michael Aram <michael_at_aram.at>
Date: Thu, 16 Jul 2015 10:46:14 +0200

Thank you, Stefan.

After fiddling around, it seems (at first sight) that the following snippet
does the trick:

if {[info command ::nx::methodParameterSlot] ne ""} {
  ::nx::MethodParameterSlot method type=sourced_guid {name value} {
    if {![::nsf::is object $value] || [xotcl::Object info instances
-closure $value] eq ""} {
      return -code error "'$value' is not an XOTcl object"
    }
    if {![$value istype ::foo::bar::SourcedGuid]} {
      return -code error "'$value' is not of type SourcedGuid but [$value
info class]"
    }
  }
  ::Serializer exportMethods {
    ::nx::MethodParameterSlot method type=sourced_guid
  }
}

All the best,
Michael

PS: For novices the "mixture" of ::nx and ::xotcl is a bit unexpected, for
example when serializing ::xotcl::MetaSlot on my OpenACS instance, one can
see, that e.g. the superclass of ::xotcl::MetaSlot is ::nx::MetaSlot et
cetera. My intuitive expectation was that both XOTcl 2 and NX exist as
different languages within NSF, but more or less completely isolated from
each other. I suppose the reason is to keep the source code required to
support the "legacy" XOTcl syntax as small as possible?


On Wed, Jul 15, 2015 at 1:58 PM, Stefan Sobernig <stefan.sobernig_at_wu.ac.at>
wrote:

> Hi Michael!
>
> What is the correct way to port this to XOTcl 2.0?
>>>
>>
> This is most likely not an authoritative answer, I don't have the time
> right now to think this through properly. The following should get you
> going for the time being:
>
> if {[info command ::nx::methodParameterSlot] ne ""} {
> ::nx::methodParameterSlot object method type=sourced_guid {name value
> args} {
> if {![::nsf::is object $value] || [xotcl::Object info instances
> -closure $value] eq ""} {
> error "'$value' is not an XOTcl object"
> }
> if {![$value istype ::foo::bar::SourcedGuid]} {
> error "'$value' is not of type SourcedGuid but [$value info
> class]"
> }
> }
> }
>
> If you plan to co-maintain two code bases (one compatible with 1.6 and the
> other for 2+), then you might want to consider factoring out the value
> checker into a plain Tcl proc and forward/alias to this proc conditionally
> from ::xotcl::nonposArgs and ::nx::methodParameterSlot, respectively.
>
> I leave this as an exercise to you ;)
>
> Let me know whether the above works for you for the time being.
>
> Cheers,
> Stefan
>
> P.S.: I suggest using "return -code error" in your value checker to skip
> one level on the callstack trace reported to the developer, to hide the
> details of the value checker in the reported trace.
>