I need to monitor all of the instances of some of the less common vanilla blocks, beds, doors furnaces and the like.

Repeatedly scanning for them is not lag friendly, so I was looking for place / remove hooks.

I found BlockEvent.BreakEvent but I can't find the matching PlaceEvent.

I tried using PlayerInteractEvent's but since these fire before the actual placement figuring out what was placed is awkward, I guess I could stash the coordinates and look them up on the next tick but that seems cumbersome.

I looked into replacing the vanilla blocks with ones wrapped with monitoring stuff, but trying to replace vanilla blocks looks like a bad idea.

Soooo, what's the correct way of doing this?

You can use Java Reflection, to solve that issue.

 

There is a method (onBlockPlaced) in vanilla Minecraft classes, (super.onBlockPlaced(***)) is required of course.

If you would like to cancel it, you could use Reflection and modify the Block class at runtime.

I wasn't aware that you could make mods like that through the reflection system and I'm not sure what to Google for, what am I looking for?

I did find redefineClasses is that the path you are suggesting?

 

And I presume since we're talking about reflection you know no native Forge way of doing this?

I found BlockEvent.BreakEvent but I can't find the matching PlaceEvent.

I tried using PlayerInteractEvent's but since these fire before the actual placement figuring out what was placed is awkward, I guess I could stash the coordinates and look them up on the next tick but that seems cumbersome.

There is no PlaceEvent probably because block placing occurs from a lot of places. Player, enderman, piston, falling sand/gravel, dispenser...

If you only care about player placed blocks, stashing the coordinates and checking later on is a perfectly valid solution.

By the same logic doesn't block breaking happen from many places? yet it has an event.