Re: [RFC/PATCH v2 0/4] A new library for plumbing output

From: Julian Phillips <julian@quantumfyre.co.uk>
Date: Apr 14, 2010, 20:57 UTC
Message-ID: <80f140cdddc016f9b4608d79f1bc3722@212.159.54.234>
In-Reply-To: <201004142110.36453.jnareb@gmail.com>

On Wed, 14 Apr 2010 21:10:35 +0200, Jakub Narebski <jnareb@gmail.com> wrote:

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> On Mon, 12 April 2010, Sverre Rabbelier wrote:
>> 
>> On Mon, Apr 12, 2010 at 01:21, Julian Phillips
>> <julian@quantumfyre.co.uk> wrote:
>> > Probably the biggest change from v1 is an expanded aim.  Now the
>> > output library
>> > is aimed at controlling _all_ plubming output.  This series includes

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>> > patch for
>> > ls-tree that has all it's output going through the library, and a
>> > patch for
>> > status that has all the --porcelain output going through the library.
>> 
>> I like where this is going, a lot, especially since we don't have to
>> convert everything in one go, but we can do it as desired, similar to
>> optparsification. I still think more commands than just these two
>> should be converted to validate the design though, perhaps something
>> like 'git blame', or 'git for-each-ref'?
> 
> I don't think it is needed for either command.

I think that the ability to say that all plumbing output is available in a variety of standard outputs is potentially useful. In particular the ability to be able to parse the output of all plumbing commands directly into whatever native language the high-level tool is in using an already existing standard parser makes life easier for those writing the tool.

> 'git blame' has --porcelain and --incremental output, which is

line-based

> and pretty much self-describing (with "header-name value" syntax for

most

> of it), and well documented.  JSON output would only add unnecessary
> chatter and different quoting rules.

That depends really. If you are writing something to parse the output, and you already have a JSON parser available then it's the current output that has different quoting rules. ;)

Anyway, I have already converted blame to use the library for both --porcelain and --incremental output, so it'll be in the next version of the patch series. So you can try before you buy ...

> 'git for-each-ref' has both --format=<format> to allow to get data what
> one needs, and in the format one wants (with e.g. %00 to reresent NUL),
> and [--shell|--perl|--python|--tcl] for placeholders in <format> to be
> quoted as string literals suitable for specified host language.

Although

> I am not sure if this option, meant to produce scriptlets, is used that
> much/ note that there is not support for --json quoting, nor --xml 
> escaping.

-- 
Julian