RE: [Yaml-core] Re: alias usage

[Oren Ben-K. <or...@ri...>]

Andrew Kurn wrote:
> On the topic of 'identity' of YAML nodes:
> 
> As so often before, much of what you say
> sounds a little weird to me . . .

:-)

> Oren:
> > The question is, what is YAML's position on this. Are YAML nodes
> > identity-based (read: require aliases structure to be preserved),
> > value
> > based (read: allow aliases structure to change), or what?
> 
> It seems obvious to me that it's not up to YAML.  If identity
> is allowed at all, it must be possible to make anything identical.
> It's the user's discretion.

Identity isn't something to "allow". It just "is" in the sense that native
data structures behave in certain ways.

I think we agree it isn't up to YAML... we agreed that it is up to the
native model to do whatever it needs/pleases, and hence that YAML models
(graph/tree/syntax) must always preserve alias structure (otherwise they
would be robbing the native model from its ability to do whatever it
needs/pleases).

In practical terms this means that the choice of whether alias==sharing is
left to the specific dumper/loader implementation for the specific type
family. This implementation may do anything it needs/pleases, and YAML
guarantees that whatever was dumped, the same thing would be loaded. I think
that answers your question:

> I think you have to let the user decide how to treat
> pointers.  It's true that you might offer him some
> policies that you think are likely to be useful most
> of the time, but you must allow him to choose anything
> at all in some cases.

Quite. The dumper can choose to use aliases, explicit pointers, whatever it
wants.

I'm not worried about "automatic dumper/loader". To dump/load a native
structure, you need to "know" it.

Have fun,

    Oren Ben-Kiki