我最近发布了一个问题,有人指出我错了!
在main()
我正在创建一个状态,然后将整数传递给processState()
并基于整数它将更改状态(通过破坏状态并创建新状态的新实例),或保持相同的状态。
向我指出的主要问题是 function void state_t::changeState(state_t * new_state)
。我正在删除this
,然后将删除的_state
指针指向新的状态。既然有人指出来,这显然是一件坏事。
那么问题来了:使用不同的状态来实现这种状态切换的最佳方式是什么?也许_state
需要是指向当前状态的全局指针或类似的?
Main.cpp
:
#include <QCoreApplication>
#include <QDebug>
#include "statemachine.h"
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
state_t *myState = new testState1();
myState = myState->processState(1);
myState = myState->processState(2);
myState = myState->processState(3);
myState = myState->processState(1);
return a.exec();
}
基础类型:
#include "state_t.h"
state_t::state_t(QByteArray stateName) :
name(stateName),
_state(this)
{
qDebug() << this->name << ": Creating state";
}
state_t::~state_t()
{
qDebug() << this->name << ": Deleting state";
qDebug() << endl;
}
void state_t::changeState(state_t * new_state)
{
// Check if the state has changed
if (this != new_state)
{
qDebug() << this->name << ": State changed to: " << new_state->name;
delete this;
_state = new_state;
}
else
{
qDebug() << this->name << ": State un-changed";
}
}
void state_t::unknownStateEventHandler(int event)
{
qWarning() << this->name << ": Unknown event " << event;
}
一个状态类(可以有很多):
#include "teststate1.h"
testState1::testState1() :
state_t("state1")
{
}
state_t *testState1::processState(int event)
{
qDebug() << name << ": event" << event;
switch (event)
{
case 2:
{
changeState(new testState2());
//changeState_t(testState2);
break;
}
default:
{
unknownStateEventHandler(event);
break;
}
}
return _state;
}