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“加一层去解决问题”：计算机解决问题的思路。怎样将其应用到代码中呢？比如亚马逊接口的开发。
git加一UI层去实现易用性和降低用户的迁移成本。
https://git-scm.com/book/en/v1/Git-Internals
Now that you’re here, let’s get started. First, if it isn’t yet clear, Git is fundamentally a content-addressable filesystem with a VCS user interface written on top of it. You’ll learn more about what this means in a bit.
In the early days of Git (mostly pre 1.5), the user interface was much more complex because it emphasized this filesystem rather than a polished VCS. In the last few years, the UI has been refined until it’s as clean and easy to use as any system out there; but often, the stereotype lingers about the early Git UI that was complex and difficult to learn.
Git is fundamentally a content-addressable filesystem with a VCS user interface written on top of it
原文：http://www.cnblogs.com/yuanjiangw/p/6753483.html