Re: [QUESTION] how to diff one blob with nothing

From: ZheNing Hu <adlternative@gmail.com>
Date: Jul 28, 2023, 03:35 UTC
Message-ID: <CAOLTT8TOs2eTryXWTy5aZ8BGNAymgjrsg1BCLbigFunkFpc7JQ@mail.gmail.com>
In-Reply-To: <20230727171334.6qg2xtecvmplg3or@carbon>

Konstantin Khomoutov <kostix@bswap.ru> 于2023年7月28日周五 01:13写道：

Show 24 quoted lines

>
> >> If you haven't created one, of course it would fail.  It should help
> >> to do
> >>
> >>     $ git hash-object -w --stdin </dev/null
> >>
> >> before running
> >>
> >>     $ git diff 00750edc e69de29bb
> >>
> >
> > This is a viable solution, but it's a bit ugly since a read-only "diff"
> > requires ”write“ an empty blob.
>
> You could probably just do
>
>   git cat-file -s e69de29bb
>
> to figure out whether a blob is empty.
>
> What is your end goal? Do you indeed want to produce a "trivial patch" which
> merely "adds" all the lines of the blob you'd like to compare to an empty one
> (assuming the blob conains text)?
>

Yes, I need to compare the diff between multiple versions of blobs in real time (only given the blobID). Once a file is deleted or created, I have to perform this comparison with the "empty blob".