Re: machine-readable explain output v4

On Monday 10 August 2009 02:53:16 Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On Monday 10 August 2009 01:21:35 Andrew Dunstan wrote:
> >> That ";" after the attribute is almost certainly wrong. This is a
> >> classic case of what I was talking about a month or two ago. Building up
> >> XML (or any structured doc, really, XML is not special in this regard)
> >> by ad hoc methods is horribly error prone. if you don't want to rely on
> >> libxml, then I think you need to develop a lightweight abstraction
> >> rather than just appending to a StringInfo.
> >
> > While it would be possible to add another step inbetween and generate a
> > format neutral tree and generate the different formats out of it I am not
> > sure that this is worthwile.
> > The current text format will need to stay special cased anyway because
> > its far to inconsistent to generate it from anything abstract and I don't
> > see any completely new formats coming (i.e. not just optional parts)?
>
> The patch as-submitted does have a lightweight abstraction layer of
> sorts, but the main code line feels free to ignore that and hack around
> it.  I agree that we can't avoid special-casing the text output, but
> I'm trying to improve the encapsulation otherwise.  What I've got at the
> moment is attached.  I'd be interested in comments on the grouping
> notion in particular --- I reverse-engineered that out of what the code
> was doing, and I'm sure it could use improvement.
Adding the notion of opening a 'empty' Group together with X_OPENCLOSE or 
handling of X_OPENING|X_CLOSING would allow to handle empty tags like in 
ExplainOneUtility (<Notify />).

Otherwise it seems to look nice.

Andres