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@ -48,7 +48,7 @@ $ git hash-object -w foo.txt |
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257cc5642cb1a054f08cc83f2d943e56fd3ebe99 |
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257cc5642cb1a054f08cc83f2d943e56fd3ebe99 |
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``` |
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``` |
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You will now find an object in the store at: |
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You will now find an object in the store: |
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```bash |
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```bash |
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$ find .git/objects -type f |
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$ find .git/objects -type f |
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@ -64,7 +64,7 @@ $ git hash-object -w bar.txt |
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257cc5642cb1a054f08cc83f2d943e56fd3ebe99 |
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257cc5642cb1a054f08cc83f2d943e56fd3ebe99 |
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``` |
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``` |
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That's right, nothing changed, this makes sense as we're only adding the content |
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That's right, nothing changed! This makes sense as we're only adding the content |
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to the object store! So how does Git remember the file names? |
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to the object store! So how does Git remember the file names? |
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## Filenames are part of tree objects |
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## Filenames are part of tree objects |
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@ -75,9 +75,11 @@ worktree, you will have a tree object. A tree object's content looks like: |
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```code |
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```code |
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<mode> <type> <hash> <name> |
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<mode> <type> <hash> <name> |
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... |
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<mode> <type> <hash> <name> |
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``` |
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``` |
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You can create this one for yourself by doing: |
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You can create a tree object yourself by doing: |
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```bash |
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```bash |
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$ git update-index --add --cacheinfo 100644 \ |
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$ git update-index --add --cacheinfo 100644 \ |
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@ -101,8 +103,8 @@ pointing too as well as some meta data. |
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## Renaming |
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## Renaming |
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Armed with the knowledge about trees and blobs, it should be fairly easy to |
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Armed with the knowledge about trees and blobs, it should be fairly easy to |
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understand what happens if you rename a file. To make not make it easier to |
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understand what happens if you rename a file. To make it easier to understand, |
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understand, consider a simple example: we just rename a file at the top level. |
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consider a simple example: we just rename a file at the top level. |
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> Note: more complex examples are just more time consuming to explain, but |
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> Note: more complex examples are just more time consuming to explain, but |
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> not to understand. The same principles apply. |
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> not to understand. The same principles apply. |
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@ -111,8 +113,9 @@ In case of such a rename, when you commit this rename, your repository will |
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be impacted as follows: |
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be impacted as follows: |
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- The blob representing the file remains unchanged. |
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- The blob representing the file remains unchanged. |
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- The top level tree object changes as it now has a different file name. |
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- The top level tree object changes as well because the filename associated with |
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- The commit object will point to the new tree. (It's parent will point to the |
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the blob is different. |
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- The commit object will point to the new tree. (Its parent will point to the |
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old tree.) |
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old tree.) |
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Nowhere is there any special mention of a rename occuring. Remember, we're just |
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Nowhere is there any special mention of a rename occuring. Remember, we're just |
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@ -124,12 +127,14 @@ However, that does not mean you lose your history when you rename a file. |
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### How to see history of a renamed file |
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### How to see history of a renamed file |
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Git might not store information on renames in it repository but it does come |
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Git might not store information on renames in the repository but it does come |
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packed with an algorithm that detects file renames. For every add/delete pair |
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packed with an algorithm that detects file renames. The way it works is that for |
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added to the index, it determines how alike the paired files are. If they are |
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every add/delete pair added to the index, it tries to determine a rename |
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at least 50% alike, it considered the pair to have been a rename. If there |
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candidate for every deleted file. It does this by comparing how similar the |
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are multiple possibilities it takes the highest percentage one. If multipe files |
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paired files are. If they are at least 50% similar, it considered the pair to |
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have the same percentage, it picks one depending on the implementation. |
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have been a rename. If there are multiple rename candidates for one file, it |
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takes the one with the highest similarity percentage. If multipe files have the |
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same percentage, it picks one depending on the implementation. |
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> **Note**: I believe, but am not sure, it basicaly takes the first |
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> **Note**: I believe, but am not sure, it basicaly takes the first |
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> alphabeticaly match in the last case. |
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> alphabeticaly match in the last case. |
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@ -146,7 +151,7 @@ You can also turn off rename detection by doing `--no-renames` |
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### Rename best practice |
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### Rename best practice |
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Because of the treshold and the cheapness of commits, it is recommended that |
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Because of the treshold and the cheapness of commits, it is recommended that |
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when you rename a file/directory. You commit those renames first, before you |
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when you rename a file/directory, you commit those renames first, before you |
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continue working on the renamed file. This basically makes it so you can use |
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continue working on the renamed file. This basically makes it so you can use |
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a treshold of 100% all the time. |
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a treshold of 100% all the time. |
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