Re: [cclib-devel] Parsers / Parsed data (Was: Re: The summer)

[Noel O'B. <bao...@gm...>]

On 09/07/07, Karol Langner <kar...@kn...> wrote:
> On Monday 25 June 2007 07:15, Noel O'Boyle wrote:
> > Actually, this makes me realise that we need to separate the parser
> > from the parsed data. Yikes! I think I always knew that this was a
> > possibility, but I never really thought about reading in data. The
> > parsers will need to create an instance of CalculationResults or
> > something, whose attributes will be aonames, etc. One of the
> > additional benefits of this, is that the data can simply be pickled to
> > a file, which is what you (Karol) should be using for your own scripts
> > for communicating between Python programs (see 'pickle' in the
> > standard library).
> >
> > Noel
>
> Yes! This is something I mentioned some time ago, in a slightly different
> context. I tried pickling some time ago, and some parser attributes (logger,
> progress) were crashing it - with this kind of separation pickling would be
> possible without additional hacks. Also, I don't think the output from pickle
> is platform-independent, so I can't freely move it between the computers I do
> calculation on - here a text format is the safest.

For the record, the output from Pickle *is* platform-independent (it's
actually just an ASCII file); the output from the faster cPickle is
*not* platform-independent (it's a binary file).

> Let's see if we are thinking along the same lines here. The parser would
> create a blank ParsedData object as an attribute in its parse() method, and
> possible return that object (return self.data)? So the syntax for using the
> parsers would need to change, to something like:
>
> >>> myparser = ccopen("....")
> >>> mydata = myparser.parse()
> >>> dir(mydata)
> ['aoname', 'natom', ....]
> >>> mydata is myparser.data
> True

Exactly. Although I wouldn't called it ParsedData, as the information
didn't necessarily come from a parsing. Why not just call it something
like cclibData, or ccData (although we don't want to get confused with
Creative Commons)?

> It strikes me that this does not require many changes in the code! It does
> imply, however, a general change in the way the parser is used. The
> ParsedData class can then a method for dumping to json or whatever. I wonder
> if there is a way to do this without changing the present syntax for parsing.
>
> Cheers,
> Karol
>
> --
> written by Karol Langner
> Mon Jul  9 09:28:32 EDT 2007
>