6 ms·

> In particular, in many other VCSs, you just simply commit without having to create a branch in the first place. Labeling them (via whichever mechanisms your V

> In particular, in many other VCSs, you just simply commit without having to create a branch in the first place. Labeling them (via whichever mechanisms your VCS provides) is typically optional with modern version control systems. Since, for me, local branches are a massive part of why I prefer git, I'd be interested in examples of how to do the same thing in other VCSs. It doesn't make sense to me that they're a byproduct of having a garbage collector, since (1) git-stash exists, (2) local branches are a common selling point, and (3) git-clean honestly seems tacked on rather than a core piece of the design.

Blackthorn 12y ago
For Mercurial, you create a new local branch by committing at a point that's not a tip (or not HEAD, if there's just a single branch). By default, it doesn't have a special name (like a git branch does). You can give it a name via "hg bookmark". The feature set is honestly fairly similar, it's just different in the way it is presented. In git you go into a "detached HEAD" and have to explicitly name a branch or commits will get lost. In hg you commit and it creates a new tip, but it doesn't have a name unless you explicitly name it via bookmark.
- josteink 12y ago
  > In git you go into a "detached HEAD" and have to explicitly name a branch or commits will get lost. Maybe I'm missing something, but this seems like a fairly academical scenario. When would you checkout a specific commit, keep working, keep committing, but not attach it to a name or a branch? How is "67846237864237846" a nicer reference than "bugfix" or whatever? To me this seems like people using git in a way it's specifically designed not to support and then go complaining when things go wrong.
  - imakesnowflakes 12y ago
    >When would you checkout a specific commit, keep working, keep committing, but not attach it to a name or a branch? How is "67846237864237846" a nicer reference than "bugfix" or whatever? You enter a commit message when you make a commit, right? So I am not sure I see your point..
    - josteink 12y ago
      I don't think you understand my dilemma. Let me try to clear it up with an example. Let's say you have the following history: - Commit 1 -> Commit 2 -> Commit 3 (master/default) - current branch Now Commit 3 is the HEAD of your current branch (master, trunk, default, whatever). The way I understand your "problem" is if you want to create a new branch based on an older, non-HEAD commit. For instance you checkout the current branch on based on the state of the branch as per "Commit 2", and make a new Commit "Commit 4". This creates a new implicit branch: - Commit 1 -> Commit 2 +-> Commit 3 (master/default) +-> Commit 4 (implicit branch) - new current branch Now you have two branches. How do you switch between them? How do you operate on those branches? Do you cycle them? Do you have to remember the last commit-message of a branch to find it again? To be absolutely clear: What I'm curious about is how do you relate to and navigate between branches when they are all anonymous? What mechanisms do you have to aid identification?
      - imakesnowflakes 12y ago
        Anonymous heads are often short lived. You either merge them right away (Making them not a head), or bookmark it (Making them not anonymous) so that you can come back to it later. But say, you forget to merge it or didn't bookmark it, Mercurial does not hide the revision from you. The hg log will list it along with all the other commits. Even easier is to use the hg heads command, which will show all branch heads for you (Branch heads are change sets that have no descendants on the same branch), along with the commit summaries. You can use the commit summary to select the revision and use a revision id (You don't have to use the full length hash, instead you can use a 4 or 5 character prefix of the revision id) to switch to that commit.
        josteink 12y ago
        I think it's funny how you say hg is much easier and git has a much more complex model, and I'm still struggling to understand all this. To me Git is clear and simple. It's a linked commit-graph, and branches and tags are just references to leaf nodes on the graph. That's all. That's the entire model. With hg you have local commit IDs, you have revsets, you have bookmarks, and then since you aren't forced to name a graph/branch you have to remember commit-IDs or who did what when to what file. Some commits show up on the commit-log, but you can't be sure if it's in the current branch. I'm totally confused as to what to use where and how I can be certain about what I'm working with. I'm not saying hg is bad per se, but looking at it from the outside it looks helluva more complex than Git. I think this all boils down to what you're used to. From the discussion in this thread here, I'm pretty certain I wont be trying mercurial anytime soon. It just seems too complex and confusing for me ;)
  - baq 12y ago
    this happens quite often in e.g. gerrit workflows, where you usually have to amend a change or if you want to take a look at somebody else's tree.
  - Blackthorn 12y ago
    > Maybe I'm missing something, but this seems like a fairly academical scenario. No, you aren't missing anything. I merely used the example to illustrate the difference between the two VCS's. Like I said: they actually have a fairly equivalent set of features. The prime user-visible difference is in interface and implementation.
rbehrends 12y ago
> Since, for me, local branches are a massive part of why I prefer git, I'd be interested in examples of how to do the same thing in other VCSs. You simply commit a new changeset based on the desired parent. The branch would be created implicitly by having a revision with two or more children. It does not have to carry a name; naming revisions (or sets of revisions) is an orthogonal concept for the purpose of navigating the revision DAG [1], whereas in Git branches have the additional purpose of keeping revisions from being GCed. Any revision that is not referenced by a ref (directly or indirectly) will eventually be GCed (once it is removed from the reflog and the grace period has expired). > It doesn't make sense to me that they're a byproduct of having a garbage collector It is a byproduct. Because if you did the above in Git (which Git won't let you without being explicit about it, but it's possible), then one or the other child would get GCed sooner or later. That's because there's only one HEAD commit, and that can prevent only one child from being GCed, so you have to create a ref to the other (generally via a branch) to keep it alive. > since (1) git-stash exists [...] and (3) git-clean honestly seems tacked on rather than a core piece of the design. This has nothing to do with git stash or git clean. I'm talking about one of Git's architectural principles, where the repository is essentially a purely [2] functional data structure and revisions that are not reachable from one of the roots (refs/branches) are subject to garbage collection. [1] And if you look (aside from Mercurial) at Bazaar, Fossil, Monotone, or Veracity, you'll find that there are multiple ways to go about that. [2] Well, not entirely pure, but close enough.
- imakesnowflakes 12y ago
  >whereas in Git branches have the additional purpose of keeping revisions from being GCed.. Not only that, but it is also used to decide what all commits to show to the user. In that way branch names act as little windows through which you can look at the DAG of history. Commits that you cannot see through this window does not really belong in the history according to git, and will be GC'ed. So if you make a commit on top of a revision that is not a branch head, then it becomes a DETACHED HEAD. Actually there is nothing 'detached' about it. It is linked to the parent commit just fine. But git just does not consider it part of the history unless you give it a name. Here you can see the problem with git naming. 'DETACHED HEAD'. If you understand a head revision as a last revision in a sequence of connected commits, how can there be a 'DETACHED HEAD' when a 'HEAD', by definition is part of a sequence of commits.. I wonder why someone would call it a 'DETACHED HEAD' instead of something like 'UNNAMED HEAD' or 'ANONYMOUS HEAD'....

Blackthorn 12y ago

For Mercurial, you create a new local branch by committing at a point that's not a tip (or not HEAD, if there's just a single branch). By default, it doesn't have a special name (like a git branch does). You can give it a name via "hg bookmark". The feature set is honestly fairly similar, it's just different in the way it is presented. In git you go into a "detached HEAD" and have to explicitly name a branch or commits will get lost. In hg you commit and it creates a new tip, but it doesn't have a name unless you explicitly name it via bookmark.

josteink 12y ago
> In git you go into a "detached HEAD" and have to explicitly name a branch or commits will get lost. Maybe I'm missing something, but this seems like a fairly academical scenario. When would you checkout a specific commit, keep working, keep committing, but not attach it to a name or a branch? How is "67846237864237846" a nicer reference than "bugfix" or whatever? To me this seems like people using git in a way it's specifically designed not to support and then go complaining when things go wrong.
- imakesnowflakes 12y ago
  >When would you checkout a specific commit, keep working, keep committing, but not attach it to a name or a branch? How is "67846237864237846" a nicer reference than "bugfix" or whatever? You enter a commit message when you make a commit, right? So I am not sure I see your point..
  - josteink 12y ago
    I don't think you understand my dilemma. Let me try to clear it up with an example. Let's say you have the following history: - Commit 1 -> Commit 2 -> Commit 3 (master/default) - current branch Now Commit 3 is the HEAD of your current branch (master, trunk, default, whatever). The way I understand your "problem" is if you want to create a new branch based on an older, non-HEAD commit. For instance you checkout the current branch on based on the state of the branch as per "Commit 2", and make a new Commit "Commit 4". This creates a new implicit branch: - Commit 1 -> Commit 2 +-> Commit 3 (master/default) +-> Commit 4 (implicit branch) - new current branch Now you have two branches. How do you switch between them? How do you operate on those branches? Do you cycle them? Do you have to remember the last commit-message of a branch to find it again? To be absolutely clear: What I'm curious about is how do you relate to and navigate between branches when they are all anonymous? What mechanisms do you have to aid identification?
    - imakesnowflakes 12y ago
      Anonymous heads are often short lived. You either merge them right away (Making them not a head), or bookmark it (Making them not anonymous) so that you can come back to it later. But say, you forget to merge it or didn't bookmark it, Mercurial does not hide the revision from you. The hg log will list it along with all the other commits. Even easier is to use the hg heads command, which will show all branch heads for you (Branch heads are change sets that have no descendants on the same branch), along with the commit summaries. You can use the commit summary to select the revision and use a revision id (You don't have to use the full length hash, instead you can use a 4 or 5 character prefix of the revision id) to switch to that commit.
      - josteink 12y ago
        I think it's funny how you say hg is much easier and git has a much more complex model, and I'm still struggling to understand all this. To me Git is clear and simple. It's a linked commit-graph, and branches and tags are just references to leaf nodes on the graph. That's all. That's the entire model. With hg you have local commit IDs, you have revsets, you have bookmarks, and then since you aren't forced to name a graph/branch you have to remember commit-IDs or who did what when to what file. Some commits show up on the commit-log, but you can't be sure if it's in the current branch. I'm totally confused as to what to use where and how I can be certain about what I'm working with. I'm not saying hg is bad per se, but looking at it from the outside it looks helluva more complex than Git. I think this all boils down to what you're used to. From the discussion in this thread here, I'm pretty certain I wont be trying mercurial anytime soon. It just seems too complex and confusing for me ;)
- baq 12y ago
  this happens quite often in e.g. gerrit workflows, where you usually have to amend a change or if you want to take a look at somebody else's tree.
- Blackthorn 12y ago
  > Maybe I'm missing something, but this seems like a fairly academical scenario. No, you aren't missing anything. I merely used the example to illustrate the difference between the two VCS's. Like I said: they actually have a fairly equivalent set of features. The prime user-visible difference is in interface and implementation.

rbehrends 12y ago

> Since, for me, local branches are a massive part of why I prefer git, I'd be interested in examples of how to do the same thing in other VCSs. You simply commit a new changeset based on the desired parent. The branch would be created implicitly by having a revision with two or more children. It does not have to carry a name; naming revisions (or sets of revisions) is an orthogonal concept for the purpose of navigating the revision DAG [1], whereas in Git branches have the additional purpose of keeping revisions from being GCed. Any revision that is not referenced by a ref (directly or indirectly) will eventually be GCed (once it is removed from the reflog and the grace period has expired). > It doesn't make sense to me that they're a byproduct of having a garbage collector It is a byproduct. Because if you did the above in Git (which Git won't let you without being explicit about it, but it's possible), then one or the other child would get GCed sooner or later. That's because there's only one HEAD commit, and that can prevent only one child from being GCed, so you have to create a ref to the other (generally via a branch) to keep it alive. > since (1) git-stash exists [...] and (3) git-clean honestly seems tacked on rather than a core piece of the design. This has nothing to do with git stash or git clean. I'm talking about one of Git's architectural principles, where the repository is essentially a purely [2] functional data structure and revisions that are not reachable from one of the roots (refs/branches) are subject to garbage collection. [1] And if you look (aside from Mercurial) at Bazaar, Fossil, Monotone, or Veracity, you'll find that there are multiple ways to go about that. [2] Well, not entirely pure, but close enough.

imakesnowflakes 12y ago
>whereas in Git branches have the additional purpose of keeping revisions from being GCed.. Not only that, but it is also used to decide what all commits to show to the user. In that way branch names act as little windows through which you can look at the DAG of history. Commits that you cannot see through this window does not really belong in the history according to git, and will be GC'ed. So if you make a commit on top of a revision that is not a branch head, then it becomes a DETACHED HEAD. Actually there is nothing 'detached' about it. It is linked to the parent commit just fine. But git just does not consider it part of the history unless you give it a name. Here you can see the problem with git naming. 'DETACHED HEAD'. If you understand a head revision as a last revision in a sequence of connected commits, how can there be a 'DETACHED HEAD' when a 'HEAD', by definition is part of a sequence of commits.. I wonder why someone would call it a 'DETACHED HEAD' instead of something like 'UNNAMED HEAD' or 'ANONYMOUS HEAD'....