Saturday, August 22, 2015

Git as a Document Format

Wil Shipley:

Undo and redo was sort of part of Core Data, but they tried to do it at the lowest level, where any time you changed the database, it just registered an undo event. This turned out to be a horrible idea. If you do any kind of housekeeping such as storing the user’s window position in the database, that suddenly becomes undoable. So, it turns out, if you have any auxiliary objects that get created, that also turns undoable. It’s not a good way to do undo.


In our perfect world of documents, we want fast loads. We don’t want to be forced to load all our data at once. We want fast saves. Fast is going to be one of the themes of our perfect world. Again we don’t want to re-save large blobs, and we’d love to have an editable format. We want autosaves to be instant, but not blow away the previous states of the document like Preview does. Undo and redo also need to be instant and never be corrupted by bad coding. We’d like them to be persistent, because that’s really cool and provides the ability to prune them.

For security reasons, you don’t necessarily want every version of your document in the document; we’ve learned that from the Microsoft Word exploits. The backup of our perfect file format should play nicely with Time Machine, which means that it shouldn’t have one giant monolithic file that changes by one byte and restarts the backup process. And, it should be incredibly easy to implement, because this is our perfect world, so why not?


As I said, you still need to decide on the file format for the control files; Git isn’t a file format that you would parse and turn into a series of drawing commands, it just gives you the files and their blobs really easily.

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