Re: [PATCH v8 7/8] cache: add empty_tree_oid object

From: Jacob Keller <jacob.keller@gmail.com>
Date: Aug 19, 2016, 20:35 UTC
Message-ID: <CA+P7+xp6VDdMnh-srDzToSwh3mZrQei+B8DjpB2N6OkqAuARkw@mail.gmail.com>
In-Reply-To: <xmqqfuq01oww.fsf@gitster.mtv.corp.google.com>

On Fri, Aug 19, 2016 at 1:31 PM, Junio C Hamano <gitster@pobox.com> wrote:

Show 15 quoted lines

> Jacob Keller <jacob.e.keller@intel.com> writes:
>
>> From: Jacob Keller <jacob.keller@gmail.com>
>>
>> Add an empty_tree_oid object which can be used in place of
>> EMPTY_TREE_SHA1_BIN_LITERAL for code which is being converted to struct
>> object_id.
>
> How widely do you envision the users of this symbol would be spread
> across the entire codebase?  I am debating myself if we need a
> singleton in-core copy like this (if we end up referring to it from
> everywhere), or we only need one level higher abstraction,
> e.g. "is_empty_tree_oid()" helper (in which case I do not think we
> even need a singleton; just imitate how is_empty_blob_sha1() is
> implemented).

If I do this, I'd also add an "is_empty_tree_sha1()" as well?

>
> Even if we need such a singleton, I think we avoid ".field = value"
> struct initializations in our code.
>

Is there a reason for that? I've found that .field = value is safer because it ensures that you don't end up initializing the wrong values? Or is it a compatibility thing?

Thanks, Jake