Return a subclass in constructor Method

Question

I have a base class which when I call constructor which accesses the system and depending on the configuration and return me a subclass of it. The main idea and the class was abstract his own factory, and returns to a sub-class as needed, depending on the config system.

I represented my idea into a draft in C + +, not necessarily to be something specific to him, but for a general approach for other language like java, etc..

is possible?

Example:

class system {
    public:
        Config config;
}

class Base {
    public:
        Base() {
            if(System.getInstance().config == Config.FooMode) {
                Foo foo = new Foo();
                return foo;
            }
        };
};

class Foo: public Base {
    public:
        float a;
        float b;
        float c;
}

class Boo: public Base {
    public:
        float d;
        float f;
        float g;
}

int main() {
    Point point = new Point();
    return 0;
}

Use a [factory method](http://stackoverflow.com/questions/5120768/how-to-implement-the-factory-pattern-in-c-correctly) instead. — Adam Rosenfield, Oct 30 '13 at 18:28
Constructors do not return in either C++ or Java (or C# for that matter). — Zac Howland, Oct 30 '13 at 18:50

score 2 · Accepted Answer · answered Oct 30 '13 at 18:27

2

Impossible. Constructors don't return anything, use another method as a factory method.

class Base
{
  Foo makeFoo()
  {
  }
  ...
};

I confused your code is C++ or Java, so don't know what code I should use.

answered Oct 30 '13 at 18:27

masoud

55,379
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score 0 · Answer 2 · edited May 23 '17 at 12:02

0

You might need to brush up your basic OO concepts. Constructors don't return anything. Well, in some sense they do return the instance of the class but you can't use any of the return types with constructors. Not even void. Why ? read THIS

edited May 23 '17 at 12:02

Community

1
1

answered Oct 30 '13 at 18:28

Prateek

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Return a subclass in constructor Method

2 Answers2