Re: Joining cg-*-id

Dear diary, on Tue, Sep 20, 2005 at 04:53:11PM CEST, I got a letter
where Linus Torvalds [off-list ref] told me that...

On Tue, 20 Sep 2005, Petr Baudis wrote:

quoted

quoted

So I'd love to have

	git diff yesterday..

but the fact is, there's no sensible semantics for it. _which_ yesterday? 
There might be five different points that are "close to 24 hours ago", 
along five different paths backwards in the history.

A well-defined meaning for this from Cogito standpoint would be "the
last commit on our HEAD before the date and all commits committed and
merged to the HEAD". In Cogito, you don't merge two branches _together_,
you merge one branch _into_ another (represented by the parents order),
so this would be sensible.

No, it's _not_ sensible or well-defined.

The order of the parents does not matter. It fundamentally _cannot_ 
matter. I realize that both git and cogito put the "primary parent" first, 
but that doesn't help one iota - because git is distributed, if the other 
side merged and we just did a fast-forward, the "primary parent" will be 
the _other_ side.

In other words, anybody who thinks that the order of parents is meaningful 
is in for some nasty shocks. It really _fundamentally_ isn't true. I 
realize that's hard to accept, but it's a truism in a distributed system. 
You really cannot have parent ordering and distribution at the same time.

Ok ok. I can now remember already learning about this once, but I forgot
again. I should write it down into some README for myself or so, I
guess. ;-) Sorry about the noise.

I'll just drop the date revision specifier support from Cogito. I don't
know if any measurable number of people actually use it in the real
world anyway.

-- 
				Petr "Pasky" Baudis
Stuff: http://pasky.or.cz/
VI has two modes: the one in which it beeps and the one in which