I was looking at a performance issue, with some code and found that the cost of creating the dynamic heap memory was the significant cost.

It would have been handy to have a class which implemented something like std::vector, but with a *small* buffer of values to use as an alternative piece of memory when the vector size was below a threshold.
Unfortunately, an array of the constructed type, would cause the constructor to be called for each array element, and for complex types, could undo the benefit of the pre-bought memory.

My proposal would be for classes (or structures) to have the ability for a member to be declared with an attribute

[[unconstructed]]
which would cause none of the constructors to actually construct the object.
The class would not naturally also call destructors.

e.g.
template< class T, size_t size>
class temp_vector
{
 [[unconstructed]] T _V[size];
 size_t m_constructed = 0;
public:
 ~temp_vector()
 {
///// Destroy the array manually.
  for( size_t i = 0; i < m_constructed; i++ ){
   _V[i].~T();
}
}
}


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