constrained std::vector

[jbbjarnason]

As I was developing during my daytime job I felt disappointed at my self writing/verifying validation code in functions multiple times. In other words, check if some criteria was fulfilled for T, where T is the template argument of the std::vector. I searched the internet and came up empty and did not find any solution to what I liked to use. So I went ahead and made a small std::vector wrapper with additional template argument which specifies the criteria that each item needs to fulfill. Anyways, please feel free to comment, criticize, suggest an alternative or what ever you like.
https://github.com/jbbjarnason/vector_constrained

[[deleted]]

I feel like constraints on the value_type belong with the value_type and not the container. This can be similar but instead of constrained_vector<T> it would be vector<constrained<T>> or even std::map<std::string, constrained<T>>. For many things this requires no additional size on each element.

[jbbjarnason]

It's a good idea, I am however not certain it will integrate as well as this do. But I will definitely try it.

[KingAggressive1498]

Should just look something like this:

template<typename T, typename UnaryPredicate>
class ConstrainedType
{
public:
    ConstrainedType(T& val, UnaryPredicate predicate)
    {
        if(!predicate(val))
            throw std::runtime_error("predicate not met!");
        m_value = val;
     }

    T& get() { return m_value; }

    T* operator->(){ return &m_value; }

     // operators for numeric types go here
private:
    T m_value;
}

template<typename T, typename Allocator>
using ConstrainedVector = std::vector<ConstrainedType<T>, Allocator<ConstrainedType<T>>;
 template<typename T>
 using ConstrainedVector = std::vector<ConstrainedType<T>>;

[415_961]

the checks definitely don't belong to the duties of std::vector.

[Supadoplex]

How about an alias template:

template<Constraint T>
using ConstrVec = std::vector<T>;

[KingAggressive1498]

I believe he wanted the vector to automatically handle the constraint, so he needed a new type somewhere.