### Behavioral Pattern#### interpreter pattern    string -> code        instruction set: 提供基本操作virtual machine: 执行指令front-end: 生成效率更高的字节码```void setHealth(int wizard, int amount);void setWisdom(int wizard, int amount);void setAgility(int wizard, int amount);void playSound(int soundId);void spawnParticles(int particleType);enum Instruction{  INST_SET_HEALTH      = 0x00,  INST_SET_WISDOM      = 0x01,  INST_SET_AGILITY     = 0x02,  INST_PLAY_SOUND      = 0x03,  INST_SPAWN_PARTICLES = 0x04};switch (instruction){  case INST_SET_HEALTH:    setHealth(0, 100);    break;  case INST_SET_WISDOM:    setWisdom(0, 100);    break;  case INST_SET_AGILITY:    setAgility(0, 100);    break;  case INST_PLAY_SOUND:    playSound(SOUND_BANG);    break;  case INST_SPAWN_PARTICLES:    spawnParticles(PARTICLE_FLAME);    break;}### stack matchineclass VM{public:  VM()  : stackSize_(0)  {}  private:  void push(int value)  {    // Check for stack overflow.    assert(stackSize_ < MAX_STACK);    stack_[stackSize_++] = value;  }  int pop()  {    // Make sure the stack isn‘t empty.    assert(stackSize_ > 0);    return stack_[--stackSize_];  }private:  static const int MAX_STACK = 128;  int stackSize_;  int stack_[MAX_STACK];};case INST_ADD:{  int b = pop();  int a = pop();  push(a + b);  break;}```### subclass 沙箱子类使用父类提供的方法#### Type Object```class Monster{}class Drogon: Monster {}class Troll: Monster {}    VSclass Breed {}class Monster{    public Breed breed;}Monster drogon = new Monster{ breed= new Breed("drogon")};Breed read config// 好处// monster的breed可以随便修改, 配置生成生物,不用重新编译代码```