Re: [RFC/PATCH 0/3] JSON/XML output for scripting interface

From: Jon Seymour <jon.seymour@gmail.com>
Date: Apr 11, 2010, 22:22 UTC
Message-ID: <q2i2cfc40321004111522kd177fb89k6b9265c641d7deec@mail.gmail.com>
In-Reply-To: <p2ofabb9a1e1004111050x660c37fdke4d5316baaa0cfbe@mail.gmail.com>

I can see that retrofitting this more widely would add quite a lot of conditional logic to a lot of places.

If one was designing for both line-oriented and structured outputs from the start, I imagine one would build a map for each record, and then hand that to the output context when it is complete, allowing the considerations of both line orientation and structured output to be encapsulated within the backend. Self-describing output formats can use a simple map without needing to know the record type, but line oriented outputs, of course, would need to know the type of record in order to select the correct line formatter.

So, would it be worth providing a hint as to record type in the output_start_object call so that if it was later desired to subsume line-oriented formats under the same framework, there is enough information available to the backend to do that?

[ And, yes, I understand that to making line-oriented formats a backend would be a reasonably invasive change to existing code that would involve a level of indirection and abstraction that may not be to everyone's taste. ]

jon.

On Mon, Apr 12, 2010 at 3:50 AM, Sverre Rabbelier <srabbelier@gmail.com> wrote:

Show 34 quoted lines

> Heya,
>
> On Sun, Apr 11, 2010 at 19:45, Julian Phillips <julian@quantumfyre.co.uk> wrote:
>> I think that there probably are commands where it will be more work to
>> integrate the output - but I think that is probably more to do with the
>> structure of the current code than the API of the new.  Does it make a
>> difference what the API of the new output code is if there isn't currently
>> a sensible hook-in point?
>
> No you are right, the existance of such hard-to-change commands does
> not really affect the API design in this case, although I think it
> might be a good idea to try out at least one such command before
> committing to using this API. For example, it might turn out that
> there's an elegant way to hook in, or that adding all those if
> (output_style != OUTPUT_NORMAL)  statements gets cluttery and there
> should be a different way to do things instead.
>
>> If code has been written without the expectation that the output format
>> could be changed then the effort to add a new output format could be
>> considerably more than for status or ls-tree.  However, with the
>> frontend/backend design hopefully we only have to endure the effort once to
>> get multiple output formats.
>
> I'm curious to see where this will lead us :).
>
> --
> Cheers,
>
> Sverre Rabbelier
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