Mercurial或git优于svn的分支/合并有什么好处？ [英] What are the benefits of Mercurial or git over svn for branching/merging?

问题描述

我曾听说过，使用git或mercurial合并分支比使用svn更容易。

在软件博客中读取最后一个Joel时，我没有得到这正是为什么。你可以提供一个具体的例子，与git / mercurial合并导致与svn相比较少的合并冲突吗？

解决方案

一个简单的例子是git可以自动将合并转换为快进。例如，假设我有一个看起来像这样的分支：

Master：

A ---> B ---> C

我创建了一个基于Master的功能分支，并提交了新的提交D和E。

特点：$ b​​
$ b

  A ---> B ---> C 
 \ 
 D --->在svn中，当您将功能分支合并回主模块时，您必须创建一个全新的提交适用于师父的D和E的变化。所以，它看起来像： 
 
 
 主人：
 A ---> B ---> C -----------------> F 
功能：\ / 
 ---> D ---> E  - > 
  
在git中，我们可以选择如何将分支功能合并到master中。如果我们做了
 
 pre $ g $ rebit feature 
 code $ pre $ 
 
 
 git会自动识别出这是一个微不足道的合并，并执行快进合并，这会将新提交添加到主分支。基础设施的结果是：
 
主人：
 
 
  A  -  - > B ---> C ---> D ---> E 
  
 Master和Feature的头都指向提交E（换句话说，它们看起来完全是相同）。快进合并与您在svn中执行更新时发生的情况类似。
另外，您可以选择强制git创建合并提交。如果我们这样做： 
 
 
  git合并功能
  
 git将创建一个合并提交。合并的结果是： 
 
 
 主人：
 A ---> B ---> C -----------------> F 
功能：\ / 
 ---> D ---> E  - > 
  
提交F是D和E的组合。
 
I've heard for instance that merging branches with git or mercurial is easier than with svn.

Reading last Joel on software blog entry, I didn't get it exactly why. Could you provide a concrete example where merging with git/mercurial lead to less merge conflicts compared to svn please?
解决方案
One simple example is git can automatically convert a merge into a "fast forward". For example, let's say I have a branch that looks like this:

Master:

A ---> B ---> C

And I create a feature branch based on Master with new commits D and E.

Feature:
A --- > B ---> C
                \
                 D ---> E
In svn, when you merge the feature branch back into master, you must create an entirely new commit that applies the changes of D and E on Master. So, it looks like:
Master:
    A ---> B ---> C -----------------> F
Feature:           \                  /
                    ---> D ---> E -->
In git we have a choice of how to incorporate the branch feature into master. If we do a 
git rebase feature
git will automatically recognize that this is a trivial merge and perform a fast-forward merge, which will add the new commits to the master branch. The result of the rebase is: 

Master:
A ---> B ---> C ---> D ---> E
Both the head of Master and Feature point at commit E (in other words, they look exactly the same). A fast-forward merge is similar to what happens when you do an update in svn.

Additionally, you have the option of forcing git to create a merge commit. If instead we do:
git merge feature
git will create a merge commit. The result of the merge is:
Master:
    A ---> B ---> C -----------------> F
Feature:           \                  /
                    ---> D ---> E -->
Commit F is the combination of D and E. 

                        
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