更改设计以避免 dynamic_cast

Question

I need some ideas on how to optimize some code that works more or less as follows:

struct Notifier
{
  void compute
  {
    for(auto& n : nodes_)
    {
      n->compute(inputs_);
    }
  }

  void add_input(input* i)
  {
    inputs_.push_back(i);
  }
  vector<input*> inputs_;
  vector<node*>  nodes_;
};

struct Node
{
  virtual void compute(vector<input*>& inputs) = 0;
};

struct GraphUpdate
{
  virtual ~GraphUpdate = {}
};

struct DerivedGraphUpdate : public GraphUpdate
{
  //specific business logic
};

struct DerivedGraphUpdate2 : public GraphUpdate
{
  //specific business logic
};

struct DerivedNode : public Node
{
  void compute(vector<input*>& inputs_) override
  {
    for(auto i : inputs_)
    {
        auto update = std::dynamic_pointer_cast<DerivedGraphUpdate>(i->getLastUpdate());
        if(update){
          //process
        }
        auto update = std::dynamic_pointer_cast<DerivedGraphUpdate2>(i->getLastUpdate());
        if(update){
          //process
        }
        //...
    }
  }
};

As you can see GraphUpdate is there just to do some basic type erasure, and everything is processed through dynamic_pointer_casts . I am trying to get my head around this problem and try to change it. Ideally I would like the Notifier to notify on the derived classes, such that instead of having a gigantic compute method that has to switch on the types using the pretty horrible dynamic_pointer_cast , it could just have some methods as follows:

void handle(DerivedGraphUpdate* d);
void handle(DerivedGraphUpdate2* d);

I don't mind that much the big compute method, but I'd like to have a way to get rid of the dynamic_pointer_cast .

To be noted, the Notifier doesn't have any knowledge of the actual derived Input and GraphUpdate types, because it was coded to be generic and it's actually on a separate codebase.

Any ideas?

Answer 1

Changing design to avoid dynamic_cast

Use a virtual function:

struct GraphUpdate
{
    virtual void process() = 0;

---

 virtual ~GraphUpdate = {}

Use = default; instead.