Question

Could you help me please.
I have one idea but don’t know how can I implement it.

So the question is:
Can we interrupt creating an object in constructor
i.e.

//Code

SomeClass someClass = new SomeClass(someCriteria);

So if someCriteria doesn’t answer on our requirements we shouldn’t create an object and should return null, instead of new object.

Is it possible to implement it in C#?

Answer 1

Best way is a factory class but if your class is so small you can use this:

class SomeClass
    {
        private string _someCriteria;

        private SomeClass(string someCriteria)
        {
            _someCriteria = someCriteria;
        }

        public static SomeClass CreateInstance(string someCriteria)
        {
            if (someCriteria.Length > 2)
            {
                return new SomeClass(someCriteria);
            }
            return null;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {

            // returns null
            SomeClass someClass = SomeClass.CreateInstance("t");

            // returns object
            SomeClass someClass2 = SomeClass.CreateInstance("test");
        }
    }