DIY_GIT_in_Python/how_to/Change_12.md

• read-tree: Extract tree from object

This command will take an OID of a tree and extract it to the working directory. Kind of the opposite of write-tree.

I divided the implementation into a few layers:

_iter_tree_entries is a generator that will take an OID of a tree, tokenize it line-by-line and yield the raw string values.

get_tree uses _iter_tree_entries to recursively parse a tree into a dictionary.

read_tree uses get_tree to get the file OIDs and writes them into the working directory.

Now we can actually save versions of the working directory! It’s nothing like proper version control, but we can see that a super basic flow is possible:

• Imagine you work on some code and you want to save a version.
• You run ugit write-tree.
• You remember that OID that was printed out (write it on a post-it note or something :)).
• Continue working and repeat steps 2 and 3 as necessary.
• If you want to return to a previous version, use ugit read-tree to restore it to the working directory.

Is it convenient to use? No. But it’s just the beginning!