Preserved files

[pjf]

It seems to make a lot of sense to mark some files as preserved, which is going to be most useful for config, but may make sense for other files as well. Preserved files don't need to be included in a distribution, we simply don't delete or overwrite them if they exist when installing or upgrading mods.

Good examples of preserved files are the TACLS and RT2 config overwrites done by RealismOverhaul, but a lot of other mods provide the capability to preserve settings between upgrades.

The rules for preserved files should be pretty simple:

• When upgrading a mod, we don't remove preserved files.
• If a mod tries to upgrade a file marked as preserved, we query the user as to what should be done.

The second follows the Debian practice of not overwriting files in /etc that the user may have customised. Care should be taken to ensure the file contents are actually changing before prompting the user.

Preserved files should be used extremely sparingly.

[henrybauer]

Here's a good example case: WernherChecker (http://forum.kerbalspaceprogram.com/threads/63591) has "checklists" that can (and are) customized by the user (GameData\WernherChecker\Data\WernherChecker.cfg). They should not be overwritten when upgrading, unless the user hasn't modified it.