CODEWITHSUNDEEP
c++boostboost-optional
dan
dan

Reputation: 1615

why not use boost::optional as a better scoped_ptr

why isn't it common place to use boost::optional as a scoped_ptr, it seems like it is better as the object is created on the stack instead of the heap. But I have never seen it used this way. My question is, what are the disadvantages of using a boost::optional as a kind of scoped_ptr other than the obvious inability to do polymorphism?

Upvotes: 1

Views: 402

Answers (2)

milleniumbug
milleniumbug

Reputation: 15814

The reason is that polymorphism is the point of scoped_ptr. Otherwise you would just declare the variable locally, on stack.

int main()
{
    Class object(52, 25); //sample declaration, with constructor arguments passed
}

EDIT 1 (response to additional info from comments):

boost::scoped_ptr is actually rarely used for the purpose you describe (mainly because you can't copy nor move boost::scoped_ptr, making the class you store it in uncopyable and unmoveable). It seems that boost::optional is appropriate for that purpose, but...

Note that there is little point in local use of boost::optional (that is, not returned from a function), since you can create objects on stack at your will:

void another_function()
{
    if(some_condition())
    {
        Class object(0, 0); // create the object
        // use the object
    }
    else
    {
        // don't use the object
    }
}

Upvotes: 3

executifs
executifs

Reputation: 1178

For one, I'd say semantics.

I would need to refresh my memory on boost::optional and boost::scoped_ptr details to give an opinion on the technical aspect, but when it comes to maintainability, using optionals in place of pointers is bound to confuse people who read your code.

Upvotes: 2

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