Re: [RFC] git-add update with all-0 object

On Friday 2006 December 01 08:10, Daniel Barkalow wrote:

If we need to explain what "index" means in the context of diff then it's not a good name :-)

An index /everywhere else/ is a lookup table. topic->page number; author->book title. record id->byte position. There is never any content in an index, indices just point at content.

I imagine that's how git's index got it's name. (I'm only guessing as I've not looked at what's actually inside git's "index"). Here's my guess:

git update-index file1 hashes file1, stores it somewhere under that hash and writes the hash->filename connection to .git/index. That is why git's index is called an index. It's a hash->filename index.

Unfortunately, "index" in colloquial git actually means the combination of .git/index plus the hashed file itself. That's no longer an index, it's a "book". :-)

It's made worse, I think, by the fact that git doesn't want to do any index-like things with the "index". Being content-oriented rather than name-oriented means that an entry like "file1->NOTHING" is impossible in git. This leads to the sort of "git-add means track this filename" confusion that turns up a lot with new users.

It's probably all too late to change the nomenclature, but I've always been of the opinion that names are important, they confer meaning. When we use a common word, with common meaning and deviate from that common meaning we are bound to create confusion. New users don't have any "git-way-of-thinking" knowledge when they begin, so when they hear "index" they can only fall back on their standard understanding of that word. We shouldn't be surprised then when new users don't get "the index".

Andy