传递派生对象的智能指针矢量-最佳解决方案是什么？

Question

I'm using boost smart pointers of two classes

class Foo{
};

class Derived : public Foo{
};

typedef boost::shared_ptr<Foo> FooPtr;
typedef boost::shared_ptr<Derived> DerivedPtr;

And I keep a vector of my objects as

std::vector<DerivedPtr> myVec;

which I want to use in a method requesting a vector of the base class smart pointers.

Method( std::vector<FooPtr> input ){
... }

Using the vector directly, gives an error on compiling.

cannot convert argument 1 from 'std::vector<DerivedPtr,std::allocator<_Ty>>' to 'std::vector<FooPtr, std::allocator<_Ty>>'

So my current solution is to first 'down-cast' my vector into a new vector of the base class pointers before passing it on:

std::vector<FooPtr> downCastVec;
for ( auto & iter : myVec )
    downCastVec.push_back( iter );

Method( downCastVec );

This works, but my actual question is:

Is there a better/more elegant way to deal with this problem?

Answer 1

Simply use the std::vector constructor overload that takes two iterators, to construct a temporary:

 Method( {myVec.begin(), myVec.end()} )

You can also declare an overload of Method() that takes the vector of derived pointers, for convenience, and just does this. This will prevent some code bloat when this is done frequently.