undoing something

I made a mistake. Big deal, now that I know that git storage is immutable and changes just add to what's already there.

A quick look at
	git reflog show topic
tells me that {1} is the one I want.  So, how do I rewind branch topic
to point to topic@{1} ?
I did it by making a tag, and then in gitk pointing to it and picking
"reset to here" from the context menu.  

A while back I was looking for the right/easy way to simply repoint my branch to where I wanted. The best answer was to use push. But, I wonder if gitk and other high-level commands simply call a more primitive command that does this? And can I call it directly? Or is push with a dot as the repository just doing this with no excessive processing and trust that the side-effects are all vacuous?

--John (please excuse the footer; it's not my choice)

TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.
  If you received this in error, please contact the sender and delete the material from any computer.

"John Dlugosz" <JDlugosz@TradeStation.com> writes:

The answer was best only because in your previous question you wanted to ensure fast-forwardness, i.e. "git push . origin/dev:dev" without plus in front to cause it to fail if it is not fast-forward.

If you know you have one unwanted commit you would want to discard at the tip of topic, you do not want fast-foward safety to kick in.

 (1) if you are on the topic branch, you can say "git reset --hard HEAD^";
     or

 (2) if you are not, you can obviously check out topic and do the above,
     or "git branch -f topic topic^".

If the garbage you have at the tip of the topic is not just a single commit, you can replace HEAD^ and topic^ in the above with whatever commit you would want to point the tip at.

=== Re: === The answer was best only because in your previous question you wanted to ensure fast-forwardness, i.e. "git push . origin/dev:dev" without plus in front to cause it to fail if it is not fast-forward. === end ===

No, I don't want to ensure ff. The remote may have been changed in other ways. Though in that case I will avoid doing so; when it is not the case it's even more important to see that your local copy is different, and understand the tree, rather than blindly pulling.

=== Re: === If you know you have one unwanted commit you would want to discard at the tip of topic, you do not want fast-foward safety to kick in.

 (1) if you are on the topic branch, you can say "git reset --hard
HEAD^";
     or

=== end ===

It was a rebase, so the old value is not under the current, or even visible on the tree. That's why I needed the reflog to find it. Tagging it let it appear in gitk.

=== Re: ===
 (2) if you are not, you can obviously check out topic and do the above,
     or "git branch -f topic topic^".
=== end ===

As documented, this destroys the existing branch and makes a new one. That would, by design, blow away the reflog for that branch. What I want is a way to re-point it, and record that repointing =in= the reflog. That is, a command-line version that does what I can do with the GUI, but isn't limited to what I can point to with the mouse.

--John (please excuse the footer, yadda yadda)

TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.
  If you received this in error, please contact the sender and delete the material from any computer.

"John Dlugosz" <JDlugosz@TradeStation.com> writes:

This is offtopic, but *PLEASE* notice that nobody else quotes like this around here. I find the style of quoting makes it unnecessarily harder to skip over parts that others wrote (and I've already read---so I do not want to waste my time on re-reading them) to get to what you are adding to the discussion quickly, and extremely annoying. It is the reason why I am skipping many of your replies to other people without reading to the end, even when I suspect you might be saying something worth reading.

I was referring to the exchange that started with this message from you:

From: "John Dlugosz" <JDlugosz@TradeStation.com>
Date: Fri, 6 Mar 2009 14:04:25 -0500
Message-ID: <450196A1AAAE4B42A00A8B27A59278E70A115E0D@EXCHANGE.trad.tradestation.com>

where you asked:

and I gave you an answer (with a typo you corrected in another message today) "git push . origin/dev:dev". In that context, you clearly want to encure fast-forward, and local push without + is an easy and safe way to do so.

That is where "it is best only because" came from. If you are not interested in ensuring fast-forward, "local push" may not be best, and there are other ways (I've shown you at least two, so I won't repeat them) to choose from.

If you can tell me how to make Outlook insert >'s in front of a block of text, I'm all ears. I can't find any kind of "quote content" or "paste as quotation" on the menus, or any option to do anything with the original message other than to put it at the end with ---original message--- in front of it. This was the best I could figure out that was useful, and gets replies threaded (mostly) properly. While you're at it, how do you tell Outlook to always start a message in "plain text" (not HTML) based on the target address, like Thunderbird does?

Alternatively, tell me how to reply using the Gmane web viewer, or point me to another web-based viewer that shows current content.

Or, the mailing list server could translate Outlook's visible interspersed quotes (the original message is blue, new typing is black) with a uniform quote style that is specified in each subscriber's preference settings.

Could be worse.  Ever use Lotus Notes?

--John

-----Original Message-----
From: Junio C Hamano [mailto:gitster@pobox.com] 
Sent: Monday, March 16, 2009 3:11 PM
To: John Dlugosz
Cc: git@vger.kernel.org
Subject: Re: undoing something

"John Dlugosz" <JDlugosz@TradeStation.com> writes:

to

This is offtopic, but *PLEASE* notice that nobody else quotes like this around here. I find the style of quoting makes it unnecessarily harder to skip over parts that others wrote (and I've already read---so I do not want to waste my time on re-reading them) to get to what you are adding to the discussion quickly, and extremely annoying. It is the reason why I am skipping many of your replies to other people without reading to the end, even when I suspect you might be saying something worth reading.

TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.
  If you received this in error, please contact the sender and delete the material from any computer.

John Dlugosz schrieb:

Tools -> Options -> Preferences -> E-mail Options, set "When replying to a message" to "Prefix each line of the original message".

Tools -> Options -> Mail Format, set "Compose in this message format" to "Plain Text".

No idea.  But why not use a real mail user agent?

Avoiding garbage is better than converting it to something useful. If someone wrote an Outlook mail sanitizer, I'd probably use it at work, too, though.

Yes, long ago, and thankfully I don't remember much about it. There's always a way to do worse -- that's small comfort.

René

That worked.  Thanks.

Because I'm using git for work, on work time, so I'm using the work computer.  It uses "exchange" instead of a real mail server.  Perhaps there are better mailers that work with Exchange, but it might not do everything the "groupware" stuff does, and that would affect the team interaction.  Also, there is a matter of "group policy" which means I'm not in full control of my own machine.

The web is barely usable from here, too.  The censor is set up, I guess, to stop ordinary desktop users like secretaries and accountants from doing anything to their machine, so the very things I'm interested in -- Windows tools, development topics, anything under ftp: -- is blocked !

--John (now if the list mailer could strip off that footer that's longer than some of my postings...)

TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.
  If you received this in error, please contact the sender and delete the material from any computer.

On Mon, Mar 16, 2009 at 4:51 PM, John Dlugosz <JDlugosz@tradestation.com> wrote:

Gmane accepts submissions via NNTP. Thunderbird is a capable NNTP client.

Perhaps sign up for a <insert favorite webmail provider here, mine is gmail> account?

But, this is seriously off-topic for this list, me thinks.

j.

No NNTP access, and webmail is expressly forbidden.  Actually, any URL that looks like it might be a web mail account is blocked.

I'm using NNTP when at home, on the weekend or whatever.  It makes it easier to reply in-thread.  And I'm using Thunderbird.

--John

TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer.

Quoting John Dlugosz <JDlugosz@TradeStation.com>:

Does it?  If so I think you have an incorrect documentation.

$ rm -fr /tmp/gomi && mkdir /tmp/gomi $ cd /tmp/gomi $ git init $ echo hello >world $ git add world $ git commit -m initial $ seq 1 100 | while read num; do echo $num >world; git commit -a -m $num; done $ git checkout -b side master~60 $ git branch -f master master@{20} $ git log --oneline -g master | head -n 10 0acf8c1 master@{0}: branch: Reset from master@{20} 945c3ee master@{1}: commit: 100 54fcb36 master@{2}: commit: 99 b314a1e master@{3}: commit: 98 e91d999 master@{4}: commit: 97 0d88853 master@{5}: commit: 96 0124315 master@{6}: commit: 95 5df2cc5 master@{7}: commit: 94 14bb58e master@{8}: commit: 93 0813a46 master@{9}: commit: 92

Nanako Shiraishi <nanako3@lavabit.com> writes:

I didn't even notice there was another question buried.  Thanks.

Documentation/git-branch.txt says this:

        -f::
                Force the creation of a new branch even if it means deleting
                a branch that already exists with the same name.

which does imply that it first destroys the branch altogether and recreates as if there was no such branch.

But that is actually not what the code does to reflog, and I think the behaviour makes a lot more sense than "destroy and create" the documentation implies. branch.c::create_branch() has this:

	if (forcing)
		snprintf(msg, sizeof msg, "branch: Reset from %s",
			 start_name);
	else
		snprintf(msg, sizeof msg, "branch: Created from %s",
			 start_name);

The message for your master@{0} example came from the "forcing" codepath.

The documentation is indeed wrong. It is more like "create a new branch, or if the named branch already exists, reset the tip of it". If we want to sound alarmist, we could add "even if it means making the existing history unreachable from the new tip of the branch", but I think "reset" already means that and it would be redundant.

The create_branch() function does another thing, though. It sets up the tracking information _if asked_. Because one branch cannot track more than one "other things" at once, it inevitably overwrites the previous tracking information if you say "branch --track -f dev origin/dev" if dev were tracking something else. But if you do not let it set up tracking, the old tracking configuration is _not_ discarded. I am not sure if that was intended (the branch.<name>.remote nor branch.<name>.merge variables are not something I use myself), but it makes sort of sense. If you do "git branch -f dev dev~2" to rewind its tip, you do not want to lose its tracking information, so the current behaviour makes sense in that respect.

I am not sure about how branch.autsetupmerge does interact with this in the current code, nor how it should interact with it in the ideal world, though. That's for interested parties (I suspect Jay and Paolo?) to figure out.

'git branch -f a b' resets a to b when a exists, rather then deleting a. Say so in the documentation.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
---
Something like this?

BTW, I noticed that 'git-subcmd' is used everywhere in here which does not feel right, but I followed the existing style, leaving a consistent clean-up for a later patch. Also, typesetting is inconsistent: We have <branch> as well as `<branch>` when the text talks about the options. Do we have a style guide or such?

 Documentation/git-branch.txt |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

Michael J Gruber <git@drmicha.warpmail.net> writes:

And what happens if the branchname does not exist?

Junio C Hamano venit, vidit, dixit 17.03.2009 17:37:

Well, the standard behaviour of "git branch" is described in the "description", the meaning of the options under "options"... We could add

	If <branchname> does not exist it is created and '-f' has no effect.

although that seems a bit talkative.

Awesome.  Then  git branch -f name newpos  is exactly what I need.  

I wondered why something that should be so simple, and is available from every GUI, is not easy from the command line.

--John

TradeStation Group, Inc. is a publicly-traded holding company (NASDAQ GS: TRAD) of three operating subsidiaries, TradeStation Securities, Inc. (Member NYSE, FINRA, SIPC and NFA), TradeStation Technologies, Inc., a trading software and subscription company, and TradeStation Europe Limited, a United Kingdom, FSA-authorized introducing brokerage firm. None of these companies provides trading or investment advice, recommendations or endorsements of any kind. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.
  If you received this in error, please contact the sender and delete the material from any computer.