CODEWITHSUNDEEP
c++return
clankill3r
clankill3r

Reputation: 9533

return the type of a class instead of an object

I want something like this:

class* defineType(ofxDTangible &t) {
    if(t.angle > PI) {
        return STSequencer;
    }
    else if(t.angle > HALF_PI) {
        return STSample;
    }
    return NULL;
}

So i want to return not an object of the class type but the type of the class itself. Is it possible?

What i want is something like this:

    classType = defineType(tang);
    if(classType != NULL) {
        // create the object somehow?
    }

It's probably bad, but i'm just wondering if it's possible.

Upvotes: 1

Views: 13137

Answers (3)

Walter
Walter

Reputation: 45414

you could define a tag to identify the class type:

enum class tag { null, sequencer, sample };
tag defineType(ofxDTangible &t) {
  if(t.angle > PI)
    return tag::sequencer;
  if(t.angle > HALF_PI)
    return tag::sample;
  return tag::null;
}

Upvotes: 0

CuriousGeorge
CuriousGeorge

Reputation: 7400

No, C++ does not have Reflection.

You can however, use polymorphism to solve this type of problem:

class ofxDTangible
{
public:
    float angle;
};

class STbase
{
public:
    virtual ~STBase(){}
};

class STSequencer : public STbase
{
public:
    STSequencer(const ofxDTangible &ofx){ /*...*/ }
};

class STSample : public STbase
{
public:
    STSample(const ofxDTangible &ofx){ /*...*/ }
};

shared_ptr<STbase> defineType(ofxDTangible &t)
{
    if(t.angle > PI) {
        return shared_ptr<STbase>(new STSequencer(t));
    }
    else if(t.angle > HALF_PI) {
        return shared_ptr<STbase>(new STSample(t));
    }
    return shared_ptr<STbase>();
}

Upvotes: 2

Daniel Frey
Daniel Frey

Reputation: 56863

The closest you can get is probably std::type_info:

const std::type_info* defineType(ofxDTangible &t) {
    if(t.angle > PI) {
        return &typeid(STSequencer);
    }
    else if(t.angle > HALF_PI) {
        return &typeid(STSample);
    }
    return NULL;
}

although I think this is really weird and you are not describing your real problem.

Upvotes: 1

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