Re: [PATCH 2/2] diff: teach diff to read gitattribute diff-algorithm

[Junio C Hamano <gitster@pobox.com>]

Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:

>> From the user's perspective, this is weirdly inconsistent with the
>> existing diff attributes, which would be more like:
>>
>>   # in .gitattributes
>>   *.json diff=json 
>>
>>   # in config
>>   [diff "json"]
>>   algorithm = histogram
>
> That does look more elegant.

We use attributes to define what it is, while configurations are
used to define what to do on different things.  The separation of
attributes and configuration came not from "elegance" or "security"
but from a lot more practical reasons.

For a tracked file, the fact that it contains JSON text as payload
does not change per user who cloned the project, or per platform the
user used to do so.  In-tree .gitattributes that the project
controls is a perfect way to define what it is for each file.

On the other hand, the diff program suitable to compare two JSON
files may vary per platform (your favorite Windows program may not
be available to me) and per user (a platform may support more than
one and the choice becomes the matter of personal taste).

The security aspect of giving users tighter control over which exact
programs are to be run by not allowing the attributes or so called
in-tree configuration mechansim is a small bonus that fell out as a
consequence.