Mod Blacklister (Forge, 1.12.2)
What and Why?
This mod aims at helping mod pack creators try to discourage the use of certain mods. This is usually done for a good reason, such as a mod being incompatible with another mod, a mod that causes a guaranteed crash, a mod that causes immense lag, etc., or simply to disallow the use of a mod because it breaks the balance or the feel of the pack.
Whenever a player adds a blacklisted mod, this mod will display an error screen during the pre-initialization step with a messaging detailing which mods caused the failure, and which files they are specifically to remedy the problem. Each blacklisted mod can also come with a message explaining why the mod was blacklisted.
This isn't a completely forced operation, as a player can just delete this mod, or re-enable the use of a mod in the config file; but this is more to act as a deterrent, or to prevent obscure errors from occurring from the player side. It is recommended that you add comments in the file alongside the disabled mods to give players an understanding as to why a certain mod might be disabled before making the decision to re-enable the mod.
How to blacklist a mod
In the mod's config file, you can add a mod to blacklist by entering the mod's id on a new line. To re-enable a mod, or to add a comment, you can start a line with a ' # '. This mod only runs during construction and pre-initialization, and for it to work effectively, the mod .jar should have a hoisted name (a name that occurs as early as possible, alphabetically), for example, "!amodid.jar" is better than "amodid.jar" because, alphabetically (according to computers), the ! character is first. You can provide a comment for each blacklisted mod that will show up during the error screen by starting the comment after the mod id. For example:
examplemod # This mod has been disabled because it provides nothing to the experience.
FAQ
Q: I blacklisted a mod, but it's still being allowed to be played.
A: Make sure you used the mod's id, not name or file name. The difference is important, as the mod id is unique to that mod, and is not version exclusive, while the mod name might change or have different styling. For example, this mod's name is "Mod Blacklister", it's jar is (by default, or as suggested) "!!!modblacklister-[version].jar", and it's mod id is "modblacklister". You can find the mod id inside the jar, or in the mod browser page in-game.
Q: I really, really want to use a mod that's been blacklisted. How can I turn it back on?
A: If the mod has been blacklisted, there is most likely a very good reason as to why. But if you want to turn it on any way, you can re-enable it by opening "(your minecraft root)/config/modblacklister.cfg" in any text editor, finding the entry that corresponds to the mod you want to re-enable, and adding a ' # ' to the start of the line. Ex: #examplemod
Q: Does this mod do anything by default?
A: By default, this mod does nothing but create a config file with instructions and an example mod to disable (which also does nothing as it has been blacklisted from being blacklisted). It shouldn't really be used casually unless you plan on sharing your mod pack with others.
Q: I added your mod and set up the config file, but another mod is still crashing during pre-initialization!
A: Make sure this mod's .jar file is the first to appear alphabetically in a folder. Forge loads mods in alphabetical order, which means that this needs to be near the top if you want it to catch other mods. The suggested name is "!!!modblacklister-[version].jar", but as long as it's above other mods, you should be fine.
If you have any issues, send me a message or open a ticket on GitHub.