超级工厂没有提供变量存储的方式，使得编程十分受限。为了解决数字存储的问题，我们可以使用一个外部存储去存储变量。利用”has”句式去返回bool变量（只包含真假两种值的变量）来判断变量的大小与数值。
64内无符号整型小数字变量快速赋值
为了存储变量，我们需要三个箱子。第一个箱子是变量对应的物品（变量来源），第二个箱子是存储变量的位置（变量存储）寄存器，第三个箱子是多余物品的去向（垃圾桶）。
这是一段c++代码：
unsigned int a =0；
a=32;
这是等效的SFM代码：
input item:: from 变量存储 slot 0
output item:: to 垃圾桶
forget
input 32 item:: from 变量来源
output 32 item:: to 变量存储 slot 0
forget
都是对某个变量初始化后，为那个变量赋一个32的值。利用这个手段，我们可以将一些数值存储在某个箱子中。对于一个普通的原版箱子，我们可以存储27个非负数的整数变量（无符号整型），与传统编程不同的是，每个变量最大值仅为64。
当然，我们可以使用模组存储或者不限定插槽来存储更大的变量。不过要小心，模组物品可能会导致意外的问题。如无必要，还是建议使用原版存储方式（木桶）。
复习：函数”has”的使用方式
由于作者只引入了”If”判断一个使用bool变量的方式，”has”在本mod中必须绑定”if”使用。
如下，是一段has在if判断中使用的例子
if barrel top side slot 0 has = 32 item:: then
else ----can delete else（if dont need this）
end
状态机引入
为了描述物体或行为的不同状态，我们引入状态机这个概念。
简单来说，状态机就是一个变量，它用不同的取值来代表系统当前处于哪种状态。如果这个变量的值和之前某个时刻一样，那就说明系统又回到了和当时相同的状态。
有了状态机，我们就可以条理清晰地针对每一种状态分别编写逻辑——也就是“按状态分别处理”。这样一来，程序结构更清晰，复杂度更容易掌控，代码的可读性也大大提升。（掉光的头发回来了）
在大多数编程规范中，状态机的变量名通常会包含“state”这个词，方便快速辨认。在SFM框架中，我们借助 “has” 关键字来编写状态机逻辑。
如下，是一段未加入行为的状态机代码，表达了0→1→2→0三种状态循环。
every 20 tick do
if state top side slot 0 has = 0 item:: then
input 1 item:: from 变量来源
output 1 item:: to state top side slot 0
forget
end
if state top side slot 0 has = 1 item:: then
input 1 item:: from 变量来源
output 1 item:: to state top side slot 0
forget
end
if state top side slot 0 has = 2 item:: then
input 2 item:: from state top side slot 0
output 2 item:: to 垃圾桶
forget
end
end
为这个循环加入行为后，可以变成这样（熔炉）：
every 20 tick do
if state top side slot 0 has = 0 item:: then -----empty furnace
input 1 minecraft:coal from chest
output 1 minecraft:coal to furnace north side
forget
input 1 item:: from 变量来源 -----empty furnace
output 1 item:: to state top side slot 0 -----furnace with fuel
forget
end
if state top side slot 0 has = 1 item:: then -----furnace with fuel
input 8 minecraft:raw_iron from chest
output 8 minecraft:raw_iron to furnace top side
forget
input 1 item:: from 变量来源 -----furnace with fuel
output 1 item:: to state top side slot 0 -----working furnace
forget
end
if state top side slot 0 has = 2 item:: then -----working furnace
if furnace bottom side slot 0 has = 8 item:: then
input 8 minecraft:iron_ingot from furnace bottom side
output 8 minecraft:iron_ingot to chest
forget
input 2 item:: from state top side slot 0 -----working furnace
output 2 item:: to 垃圾桶 -----empty furnace
forget
end
end
end
#当然，实际使用中我们不会用状态机控制如此简易的状态循环。状态机的对手是多状态满足一定条件后的状态间互相跳变。
#良好的编程习惯：由于SFM没有提供定义与引用函数块的方式，建议在注释中写清楚各种状态的含义。对于巨量的状态（真的存在于MINECRAFT中吗），建议专门留出几行注释空间将状态的含义写在一起。
状态机使用样例
状态机使用样例1：大部分单主材多合一产线（主材第一个输入）
name “fusion”
every 20 tick do
if state slot 0 has = 1 item: then -----empty fusion
if not source has = 0 item:: then
input item:: from source slot 1-26
output item:: to each assistant
forget
if source has = 1 item:: then
input 2 item:: from 变量来源 -----empty fusion
output 2 item:: to state slot 0 -----ready except the main item
forget
else
input 1 item:: from 变量来源 -----empty fusion
output 1 item:: to state slot 0 -----stacked main item and assistant
forget
end
end
end
if state slot 0 has = 1 item: then -----stacked main item and assistant
input 1 item:: from source
output 1 item:: to empty slot in each assistant each side
forget
if source has = 1 item:: then
input 1 item:: from变量来源 -----stacked main item and assistant
output 1 item:: to state slot 0 -----ready except the main item
forget
end
end
if state slot 0 has = 2 item:: then -----ready except the main item
input item:: from source
output item:: to core
forget
if core has = 1 item:: then
input 1 item:: from 变量来源 -----ready except the main item
output 1 item:: to state slot 0 -----start fusion
forget
end
end
if state slot 0 has = 3 item:: then -----start fusion
if each assistant has = 0 item:: then
if product has = 1 item:: then
input 1 item:: from 变量来源 -----start fusion
output 1 item:: to state slot 0 -----end fusion
forget
end
end
end
if state slot 0 has = 4 item:: then -----end fusion
if not product has = 0 item:: then
input item:: from product
output item:: to storage
forget
else
input item:: from state slot 0 -----end fusion
output item:: to 变量来源 -----all products stored, empty fusion
forget
end
end
end
状态机使用样例2：机械动力精密构件（利用状态机控制复杂程序的运行，节省占用）
name “create:precision_mechanism”
every 220 tick do
input minecraft:iron_nugget from me_1
output item:: to hand_3 each side
forget
input create:cogwheel from me_1
output item:: to hand_1 each side
forget
input create:large_cogwheel from me_1
output item:: to hand_2 each side
forget
if state slot 1 has = 0 item:: then -----empty factory
if not source has = 0 item:: then
input 1 item:: from 变量来源 -----empty factory
output 1 item:: to state slot 1 -----running factory
forget
end
end
if state slot 1 has = 1 item:: then -----running factory
input 1 item:: from depot_3
output 1 item:: to temp
forget
input 1 item:: from depot_2
output 1 item:: to depot_3
forget
input 1 item:: from depot_1
output 1 item:: to depot_2
forget
input create:precision_mechanism from temp -----try output product
output 1 item:: to storage
forget
if temp has = 0 item:: then -----if output successfully
input 1 item:: from source
output 1 item:: to depot_1
forget
else
input 1 item:: from temp
output 1 item:: to depot_1
forget
end
if overall depot_* has = 0 item:: then
input 1 item:: from state slot 1 -----running factory
output 1 item:: to 变量来源 -----empty factory
end
end
end
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