6

Assume I clone a repository OSS at version 1.0 containing a class A. Subclassing A is not enough for me, so I copy A to A' and make some modifications to it. At a later point in time, I clone OSS at version 1.1, containing an updated version of A. How can I merge the changes/updates from A to my modified copy A'? Is there a standard pattern for such cases?

stefan.at.kotlin
  • 15,347
  • 38
  • 147
  • 270
  • 3
    Why do you copy `A` instead of directly modificating it? It would be easier to pull the changes from upstream and rebase your modifications on top of them. – bfontaine Aug 19 '20 at 16:45
  • 2
    `A` is a UI widget and I need both, the original and a modified version of it – stefan.at.kotlin Aug 19 '20 at 16:59

1 Answers1

6

The idea is to:

  • create the patch using git diff: between A#1.0 and 1#1.0

    git diff 1.0 1.1 -- A > a.patch

  • then apply that patch using the patch utility: you can specify the file you want to apply the diff to with patch.

    patch -p1 A' a.patch

On Windows, use a simplified PATH as in here, and you will see patch available:

C:\git\>where patch
C:\prgs\gits\current\usr\bin\patch.exe
VonC
  • 1,262,500
  • 529
  • 4,410
  • 5,250
  • thanks for your reply. I could execute the first command, but failed for the second one, as I am on Windows (no patch command). Any way to apply the patch using Git? – stefan.at.kotlin Aug 22 '20 at 12:40
  • @stefan.at.wpf If you installed GIT under Windows then launch 'Git Bash' and you will find that you do have a `patch` command. – Booboo Aug 22 '20 at 12:53
  • @stefan.at.wpf I have edited the answer to add the right Windows `%PATH%` for you to use `patch`. – VonC Aug 22 '20 at 14:16
  • Thank you both :-) My first limited test looks promising, actually I feared that `patch` would complain because of different class names, but somehow patch seems to be intelligent enough to detect that `A'` is just mentioned at the places were earlier `A` was mentioned, great. I will do some more testing if it also works for more advanced cases. – stefan.at.kotlin Aug 22 '20 at 14:47
  • @stefan.at.wpf Great! Well done. Let us know of your results. – VonC Aug 22 '20 at 14:55