CODEWITHSUNDEEP
c++c++17
newbie
newbie

Reputation: 35

shared_ptr to derived class

I am fairly new to C++ and I am still learning to write clean code.

Below are excerpts from the current legacy code I have.

class A {
public:
    setDataManager(dm)
    {
        _dm = dm;
    }

    void recieveData(data)
    {
        _dm.processData(data);
    }

private:
    std::shared_ptr<DataManager> _dm;
};

class DataManager {

public:
    void processData(data)
    {
        DecodeData dd;
        dd.Decode(data);

        if (decoded data conatains a value XYZ) {
            doActionA();
        }
    }
};

class DecodeData {

public:
    void decode(data)
    {
        //if data contains key 1
        // store the value (setters and getters defined)
        //if data contains key 2
        // store the value.
        ......
    }
};

main()
{
    //ConfigManager reads the location type from config file

    A a;
    std::shared_ptr<DataManager> dm = std::make_shared<DataManager>(...);
    a.setDataManager(dm);

    //a.recieveData() gets called
}

The Data received is specific for the type of location.

Currently, the legacy code is defined only for one location(NewYork).

Now I have to add another location to the configuration Manager(Australia). That means I need to add more statements to decode(data) and additional doActions() in processData();

I want to write clean code by separating out the processing for location NY and Australia, as the data received is different for different locations. I want to have base class, and split out the processing based on location types.

I am unable to conceptualize it. Is it possible? How do I approach it?

Thank you.

Upvotes: 0

Views: 116

Answers (1)

Jeffrey
Jeffrey

Reputation: 11400

You can create a shared pointer to a derived class and assign it to a shared pointer to a base class. That seems to be the only piece you are missing.

https://godbolt.org/z/Gf7fb1

#include <memory>

class Base 
{
    public: 
        virtual int Foo(); 
};

class Derived:public Base
{
    public: 
        virtual int Foo(); 
};

int main()
{
    std::shared_ptr<Base> ptrBase = std::make_shared<Derived>();
    ptrBase->Foo();
}

So, in your case, you just need to create the right type of DataManager with something like

std::make_shared<DataManagerSpecial>;

and pass it in. Then, be sure the DataManager has the correct and flexible API in its base class. DataManagerSpecial obviously needs to derive from DataManager.

Upvotes: 2

Related Questions