Re: [Tclxml-devel] Document Management in TclXML v3.0

[Joe E. <jen...@fl...>]

Steve Ball wrote:
>
> I've been working on TclXML v3.0 and trying to incorporate
> some new ideas on document and node management.  In particular,
> your request to have implicit document destruction has
> been implemented.  However, I'm now at the point where
> I just cannot get it to work reliably.

[... explanation deleted ...]

> My conclusion is that object shimmering defeats any attempt
> to have mutable objects automatically garbage collected.

That's a correct conclusion.  This sort of thing just
isn't possible in Tcl.  Of course some extensions do
it anyway, but there is no way to make it 100% reliable.

> At this point there is a choice: don't define document node commands
> (ie. stay with the v2.x TclDOM API) or require explicit
> destruction of documents.  At this stage my preference is for
> the latter.

Even if you don't define document node commands, there are
still other opportunities for shimmering.  ([eval] is probably
the main one; there are many others.)

It's possible, with great care, to write code that avoids
shimmering altogether, but IMO that places too large a burden
on application programmers.  I'm strongly in agreement with
Steve's preference for explicit destruction.


--Joe English

  jen...@fl...