Can't branch a single file with Mercurial? - mercurial

is this possible with Mercurial? and which Version Control system can do this besides Clearcase?

David is correct that you can't have a branch that exists on only a single file, but it's worth pointing out that people often have branches that alter only a single file. Since the branch metadata is stored in the changeset, and since the changeset contains only a delta (change), having a branch that alters only a single files is nearly instantanous to create, update, commit, and merge, plus it takes up almost no space on disk.
Resultingly, it's a very common way to handle per-customer configurations. Keep the tiny change for them in a branch, and merge from main, where development happened, into that branch, whenever you want to update their deployment.

How you could use MQ:
$ hg qnew -m "Changes for client0" client0
... change the file ...
$ hg qref # update the client0 patch with the changes
$ hg qpop # pop the changes off the queue stack
... develop like normal ...
... client0 asks for a build ...
$ hg qpu # apply client0's patch
$ make release
$ hg qpop
It would get a bit finicky if you've got to deal with a lot of clients… But it may be worth considering.
The other thing you could do, of course, is just commit a bunch of .diff files:
... make changes for client 0 ...
$ hg diff > client0.diff
$ hg revert --all
$ hg add client0.diff
$ hg ci -m "Adding client0 changes"
... develop ...
... client0 asks for a build ...
$ patch -p1 < client0.diff
$ make release
$ hg revert --all

No, it's not possible. A branch in Mercurial is a snapshot of the entire repository state.
You could do it with CVS, though, as CVS tracks changes on a per-file basis :)

Related

How to undo "hg qnew"?

I issued hg qnew without realizing that it includes any outstanding changes into the patch. I'd like to back that out and pick only specific changes using hg qrecord. How can I undo qnew?
Your answer definitely works — with newer Mercurial's you can use hg strip --keep to avoid doing the import step:
$ hg strip --keep .
$ hg qdelete patch-name
The --keep flag makes strip ignore the working copy while working, that is, it deletes the commit (like hg qpop would do) but it doesn't undo the changes to the files. After stripping you still have the patch in your series (unapplied) and you can then delete it.
I've found an anwer here:
hg qpop
hg import --no-commit .hg/patches/patch-name
hg qdelete patch-name
Please add a better way, if you know.
Update: Based on Aldo's answer, there is another way:
hg qnew test
# We can undo the above qnew as:
hg qrefresh -X '*'
hg qpop -f
hg qdelete test
If you just want to undo the latest qnew retaining all your local changes, one option is:
qcrefresh 123
hg qpop -f
hg qdelete <name of the patch>
Notice that 123 is just a random string: you are telling mercurial to only include the (hopefully nonexistsnt) 123 file in the current patch.
Newer versions of Mercurial When you issue will issue a warning about the fact 123 file does not exist, but this is exactly what we want here.
If you want to retain some of the changes in the current path, you can use the qcrefresh command from the crecord extension, which allows to graphically select the changes to be included in the current patch. You need to download it from Bitbucket, extract the archive and configure it in .hgrc:
[extensions]
crecord = <path/to/crecord/package>

Mark changes as already merged or deliberately ignored with hg pull/push/merge/graft?

I'm transitioning to Mercurial from Subversion, where I'm used to using svnmerge.py to track changes that have already been merged, or which have been blocked from being merged:
# Mark change 123 as having already been merged; it will not be merged again, even if a range
# that contains it is subsequently specified.
svnmerge.py merge -M -r123
#
# Block change 326 from being considered for merges.
svnmerge.py merge -X -r326
#
# Show changes that are available for merging from the source branch.
svnmerge.py avail
#
# Do a catchall merge of the remaining changes. Neither change 123 nor change 326 will be
# considered for merging.
svnmerge.py merge
I want to be able to do something similar for hg pull/push/merge/graft, so that if I know that I never want to merge a given change, I can just block it from consideration, making subsequent cherry-picking, merging, etc., into a more fire-and-forget affair. I have done a lot of googling, but have not found a way to do this.
There also appears to be no way to view a list of as-yet-ungrafted changes.
As I'm often tidying up after other developers and helping them with their merges, it's immensely helpful to be able to do these kinds of things, which one might well consider "inverse cherry-picking;" i.e., marking changes that you do NOT want to merge, and then doing a bulk merge of the remainder.
DAG-based systems like Mercurial ans Git are all or nothing: when you merge two branches, you do a three-way merge of the common ancestor and the two branches.
The three-way merge is only concerned with the final stage of each branch. For instance, it doesn't matter if you make your changes in 10 it 1000 steps — the merge result will be the same.
This implies that the only way to ignore a changeset is to back it out before the merge:
$ hg backout BAD
That will cancel the changeset on the branch, making it appear that it was never made from the perspective of the three-way merge.
If you have a whole branch that you want to merge, but ignore, then you can do a dummy merge:
$ hg merge --tool internal:local --non-interactive
$ hg revert --all --rev .
That goes through the merge, but reverts back to the old state before committing.
The best advice I can give you is to structure your workflow so that the above backouts aren't necessary. This means committing a bugfix on the oldest applicative branch. If a bug is found while creating feature X, then use hg bisect to figure out when the bug was introduced. Now updated back to the oldest branch where you still want to fix the bug:
$ hg update 2.0
# fix bug
$ hg commit -m "Fixed issue-123"
then merge the bugfix into all later branches:
$ hg update 2.1
$ hg merge 2.0
$ hg commit -m "Merge with 2.0 to get bugfix for issue-123"
$ hg update 2.2
$ hg merge 2.1
$ hg commit -m "Merge with 2.1 to get bugfix for issue-123"
If the bugfix no longer applies, then you should still merge, but throw away the unrelated changes:
$ hg update 3.0
$ hg merge 2.2 --tool internal:local --non-interactive
$ hg revert --all --rev .
$ hg commit -m "Dummy merge with 2.2"
That ensures that you can always use
$ hg log -r "::2.2 - ::3.0"
to see changesets on the 2.2 branch that haven't been merged into 3.0 yet.

Generating patches in Mercurial

I've looked for that in the manual, but I can't generate a patch for the last commit.
I tried
hg qnew patch_name
but it does only file with
# HG changeset patch
# Parent a6a8e225d16ff5970a8926ee8d24272a1c099f9c
I also tried
hg export tip
but it doesn't do anything. I committed the changes exactly.
How to generate a patch file with the last commit in?
The command to do this is export:
$ hg export -o FILE -r REV
It doesn't require redirection and will thus work correctly on any platform/shell.
Your hg export tip is the best way to do it, and the hg diff and hg log based answers are just lesser versions of the same. What exactly do you see/get when you type hg export tip? What does the output of hg log -p -r tip show?
The changeset tip is just means "the changeset that most recently arrived in my repository" which isn't as useful a concept as you might think, since hg pull and hg tag all create changesets too. If you really want the last thing you committed you'll need a more precise revspec.
Like so:
hg diff -r tip > tip.patch
You can use this command:
hg log -r tip -p > tip.patch
this will generate a patch for just that revision.
If you want to convert the latest commit to a patch file, use
hg qimport -r tip
This will replace the topmost regular commit with an applied MQ patch file.
To generate patches using "mq extensions" in mercurial, you can follow the below given steps. This will create a patch using mercurial:
1) Enabling mq extensions: Add the following lines to your hgrc file and save it.
[extensions]
mq =
2) Creating a patch using mq extensions: To create a patch using mq extensions you can do the following.
hg qnew -e -m "comment you want to enter" bug_name.patch
In the above command, -e flag is for editing the patch and -m flag is for adding a message to the patch.
3) Updating the patch: For updating the patch, you can use the following command when a patch is already applied.
hg qrefresh

In Mercurial how do I extract a single file's changes from a Changeset to apply to another branch?

I have a large commit of many files on one branch, I need to transfer the modifications of a single file in that changeset to another branch. How can I do this? I am mostly using TortoiseHg but commandline solutions are also fine.
If I go to the changeset in TortoiseHg and select the file I can see the diffs I want to transfer, but not a way to actually apply them.
You can get the patch for just that file using:
hg log -r THEREVISIONWITHLOTSOFCHANGES -p -I path/to/justthatfile > justthatfile.patch
which you can then import on whatever branch you want by doing:
hg update anotherbranch
hg import --no-commit justthatfile.patch
hg commit
The most basic solution is to dump the patch of the file, apply it to the current working revision, and commit it (assuming you're at the root of the repository):
$ hg up <revision-to-apply-the-patch-to>
$ hg diff -c <revision-containing-the-patch> <files-to-include> | patch -p0
$ hg ci -m "Transplanting selected changes from <revision-contain...>"
The drawback of this method is that it isn't very obvious what you've done from a revision history perspective. A good commit message helps here, but the history graph gives no hint about the process of transplanting some changes. In that case merging and reverting may be a better solution:
$ hg up <revision-to-apply-the-patch-to>
$ hg merge -r <revision-containing-the-patch>
$ hg revert --no-backup <files-to-exclude>
$ hg ci -m "Merge in changes of <files-to-include>"
Probably there are more solutions to do this -- these two came to my mind first.

mercurial push certain revision

I have searched here, but haven't found any question related to this. I got a problem like this in mercurial:
I manage open source project in bitbucket, so i have clone of the source code in my local. But I also using that project for my own live site, so I made 2 clone of bitbucket repo
Bitbucket Repo
|
==local_clone1
|
==local_clone2-> commit1 => commit2 => commit3
(personalization) (bug fix) (add feature)
The question is, I want to push commit2 and commit3 back to local_clone1, so later on I can push to Bitbucket repo. But don't want to push commit1, since it has my personal data.
Wondering how we do that in mercurial?
This can be done without too much difficulty in this case. See Removing history in the Mercurial guide for more information.
Here's the basics of what you'll need to do:
Go to local_clone2
Get the revision number (hg tip will show you) from the current number. We'll call it 731.
hg export 730-731 > ../local_clone1/changes.diff (or wherever you like)
Go to local_clone1
hg import changes.diff
You may need to edit things manually; refer to that guide for more info in that case.
Here are a couple of options:
backout
Given a history constructed as:
hg init db
cd db
echo >file1
hg ci -Am clone # rev 0
echo >file2
hg ci -Am personalization # rev 1
echo >file3
hg ci -Am bugfix # rev 2
echo >file4
hg ci -Am feature # rev 3 <tip>
Then if the current working directory is the tip, the following commands will "undo" the personalization revision:
hg backout 1
hg ci -m backout
The advantage is history remains immutable, but shows the addition and backout of the personalization changeset.
Mercurial Queues
With the mq extension, history can be edited to remove a changeset:
hg qimport -r 1:3 # convert changesets 1-3 to patches
hg qpop -a # remove all patches (can't delete an applied patch)
hg qdel 1.diff # delete rev 1's patch
hg qpush -a # reapply remaining patches
hg qfin -a # convert all applied patches back to changesets.
The advantage is the personalization changeset disappears. The disadvantage is the changeset hashes change due to the history edit, so this should never be done to changesets that have already been pushed to others. There is also the risk of a mistake editing history.