Crash Course in the Basics

Note

This tutorial assumes that you have read Getting Started. If you have not, do so before reading this tutorial.

LootTweaker makes use of some features of CraftTweaker that you may not be familiar with, even if you have used CraftTweaker before. This tutorial provides a quick crash course in those features.

Crash Course in Object Oriented Programming

ZenScript (The language all MineTweaker/CraftTweaker scripts are written in) supports a particular way of programming called Object Oriented Programming (OOP).
The following OOP terms are used in this documentation
type

a definition of a particular kind of thing and how it behaves.

instance

a representation of particular kind of thing. Created from a type.

As an example, consider the type loottweaker.LootPool, which represents a loot pool. There is only one type called loottweaker.LootPool, but there are many instances of it, one for each loot pool.

method

a named section of runnable code

call

to make a method run its code

parameter

data that must be supplied to call a method

return

a method is said to ‘return’ when it stops running its code. Some methods output an instance when they return.

static method

a method that can be used without an instance of the type it is defined by.

instance method

a method or field that can only be used with an instance of the type it is defined by.

An example of a static method is the method getTable of the type loottweaker.LootTweaker.
Calling it looks something like this loottweaker.LootTweaker.getTable("minecraft:entities/pig").
Common notation for a static method is type_name.method_name(), e.g. LootTweaker.getTable(). Parameters are not included in the notation.
An example of an instance method is the method getPool of the type loottweaker.LootTable.
Calling it looks something like this pigTable.getPool("main"), where pigTable is an instance of loottweaker.LootTable.
Common notation (not syntax, so not valid code!) for an instance method is type_name#method_name(), e.g. LootTable#getPool(). Parameters are not included in the notation.

Crash Course in Local Variables

ZenScript allows you to store a particular piece of data for later under a particular name. This is done using the var & val keywords, the difference is that var allows you to change the piece of data the name refers to, while val does not. They allow you to replace this

LootTweaker.getTable("foo").getPool("bar").removeEntry("baz");
LootTweaker.getTable("foo").getPool("bar").removeEntry("qux");

with this

val fooBar = LootTweaker.getTable("foo").getPool("bar");
fooBar.removeEntry("baz");
fooBar.removeEntry("qux");

Much easier to read isn’t it? Note that they store the value returned by the call on the right side of the =, they do not execute that code when referenced. More information about local variables.

Explanation of an Example Snippet

Let’s have a look at an example snippet. You won’t know the methods used yet, but that’s not important.

//Get the cow loot table and store it for later use
val cow = LootTweaker.getTable("minecraft:entities/cow");

//Get the pool named "main" from the cow loot table and store it for later use
val cow_main = cow.getPool("main");

//Remove leather from "main"
cow_main.removeEntry("minecraft:leather");

This snippet prevents cows dropping leather.

  1. The cow loot table is retrieved and stored

  2. The pool called “main” is retrieved from the table and stored

  3. The entry called “minecraft:leather” is removed from the pool

Two of the methods in the snippet, getPool() & removeEntry() are instance methods. They must be called on an instance of LootTable & LootPool respectively. In the case of getPool() the instance used is the one returned earlier by LootTable.getTable(). In the case of removeEntry() the instance used is the one returned earlier by getPool(). LootTable.getTable() is the only static method.

You are now ready to move on to the next tutorial.