Differences

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--- safety-features [2021/04/29 14:47] – shane
+++ safety-features [2023/05/08 18:59] (current) – external edit 127.0.0.1
@@ Line 8: / Line 8: @@
 ===== Auto-save and the Revert button =====
-Unify maintains a special folder (//Auto-Saved Patches// under the main Unify data folder) where it automatically saves a copy of your current patch, any time you might lose it by e.g. hitting the **Init** button, clicking on a patch in the patch browser to load it, clicking the Next/Prev arrow buttons, or quitting the Unify stand-alone app.
+Unify maintains a special folder (//Auto-Saved Patches// under the main Unify data folder) where it automatically saves a copy of your current patch, any time you might lose it (i.e., if Unify detects a change in the patch data in memory; see [[#how_unify_detects_patch_changes|How Unify detects patch changes]] below) by e.g. hitting the **Init** button, clicking on a patch in the patch browser to load it, clicking the Next/Prev arrow buttons, or quitting the Unify stand-alone app.
 If you do any of these things, and need to get back to the patch you were working on, click the **Revert** button at the top-right corner of the Unify GUI, to bring up the **Revert menu**, which will look something like this:
@@ Line 30: / Line 30: @@
 {{::are-you-sure.png|}}
-Click **OK** to complete the action you started (the current patch //will still be auto-saved//, if auto-save is enabled)
+Click **OK** to complete the action you started (the current patch //will still be auto-saved//, if auto-save is enabled). Click **Cancel** to cancel the action and remain where you are (the current patch will not be auto-saved).
+==== Why is "are you sure?" OFF by default? ====
+Perhaps surprisingly, for a host program like Unify to detect whether or not the current patch has changed is actually quite complicated, because it has no way of knowing what changes may have occurred inside third-party plug-in instances. See the next section for details.
+===== How Unify detects patch changes =====
+Unify uses a simple method to check for patch changes:
+  * When the patch is loaded, Unify computes and stores a checksum of the patch data.
+  * When you initiate any action that might overwrite the current patch (Init, patch load, etc.), Unify re-computes the checksum, compares it against the stored one, and will assume the patch has changed if they are not the same.
+This checksum algorithm is simple, quick, and unlikely to produce "false negative" results. However, it's also //hyper-sensitive//--the slightest change can trigger it, even using your mod-wheel, or any MIDI CC control linked to parameters via a macro knob, OR via "MIDI-learn" or programmed linkage within some third-party plug-in.
+Unfortunately, there are also some plug-ins which will trigger the checksum algorithm every time, even if nothing has changed in the patch, because they simply work that way. Even the built-in [[combobox|ComboBox]] utility plug-in does this.
+Because of this hyper-sensitivity, you will see the "are you sure?" pop-up a lot, even when you really don't expect to. For this reason, we decided to make it optional, and OFF by default.