ITCL #auto object name

[JonoK]

Hi,

I'm learning/experimenting with ITCL with a view to using it for a project. I'm using 8.6, and the version of ITCL that comes bundled with that.

So, when I use #auto to auto generate an object name I get back something like classA0, classB1 ... which is fine, except it's not the actual name of the object ... later on when I try to use the object from a different context I get an unknown command error: it appears that the name of the object is the name within the local context when the object was created, something like ::classA::classB1.

I've worked around this by using a proc to generate a global name at each object creation point, but that's a bit cludgy.

Is there a way to make the auto name global? Or is there an elegant way to only have the name generation override in one place.

TIA
Jon

[Donal K. Fellows]

On 12/09/2012 00:45, JonoK wrote:
> Is there a way to make the auto name global? Or is there an elegant
> way to only have the name generation override in one place.

It sounds to me like that's a bug in the name generation code; itcl 4
(the version you're testing) has been substantially rewritten from
previous versions, and it sounds like this is a place where an issue
remains. (I've got an idea about what's going on; it's probably linked
to a change in the semantics of name qualification in the TclOO
constructor layer that itcl 4 is building on top of. TclOO itself is
immune because it uses a different algorithm for automatic name
generation. The fix is to do a little adjustment to the name
construction code in Itcl_HandleClass in itclClass.c; I think adding a
'::' in the right spot will do the trick, it's a one-liner.)

Fortunately, this is actually likely to be easy to fix quickly. We're
testing release candidates of Tcl 8.6b3, so a critical problem like this
can be dealt with very rapidly. I've filed a bug report attaching your
message and my suggested fix (and, importantly, its consequences):

https://sourceforge.net/support/tracker.php?aid=3566940

Donal.

[Ralf Fassel]

* "Donal K. Fellows" <donal.k...@manchester.ac.uk>

| On 12/09/2012 00:45, JonoK wrote:
| > Is there a way to make the auto name global? Or is there an elegant
| > way to only have the name generation override in one place.

--<snip-snip>--

| Fortunately, this is actually likely to be easy to fix quickly. We're
| testing release candidates of Tcl 8.6b3, so a critical problem like this
| can be dealt with very rapidly. I've filed a bug report attaching your
| message and my suggested fix (and, importantly, its consequences):
>
| https://sourceforge.net/support/tracker.php?aid=3566940

We've used something like
set object [SomeItclObject ::\#auto]
to work-around this problem.

Maybe the proposed change should check whether there is already
a "::" at the start of the name...

R'

[Michael Barth]

[Donal K. Fellows (Wednesday 12 September 2012 10:14)]:

It's not a bug, it's feature. :-(

Even earlier versions have this feature: The instantiation of a class
returns NOT the full class name, but only the defined name.

Solution: Use [namespace current]:

MyClass [namespace current]::#auto

Or write a wrapper around your class:

proc myclass {args} {
eval MyClass [uplevel namespace current]::#auto $args
}

Regards
Michael

[Donal K. Fellows]

On 12/09/2012 00:45, JonoK wrote:

> So, when I use #auto to auto generate an object name I get back
> something like classA0, classB1 ... which is fine, except it's not
> the actual name of the object ... later on when I try to use the
> object from a different context I get an unknown command error: it
> appears that the name of the object is the name within the local
> context when the object was created, something like
> ::classA::classB1.

After discussions, it seems that this is the way it is supposed to work;
it's a documented feature, though the documentation of the consequences
could be rather clearer. (I don't care for doing it this way, but there
you go.)

> Is there a way to make the auto name global? Or is there an elegant
> way to only have the name generation override in one place.

To get a global name, use a qualified-name to request it such as
“::#auto” (which will put the object in the global namespace and return
the fully-qualified name). The alternative is to apply [namespace which]
to the result of the creation with a plain “#auto” to get the fully-
qualified name.

Donal.

[JonoK]

Thanks for the clarification.