Question

I have the following code -> something like Select case using LINQ –
This is not the actual code [picked from internet].
Just trying to show the Select Case concept using LINQ.
In my code, based on the conditions I am creating new List objects

Int32[] numbers = new Int32[] { 1, 2, 1, 3, 1, 5, 3, 1 };

var numberText =
(
    from n in numbers
    where n > 0
    select new
    {
        Number = n,
        Text = 
        (
            n == 1 ? "One" :
            n == 2 ? "Two" :
            n == 3 ? "Three" : "Unknown"
        )
    }
);

But, the page here says – “Replace condition with polymorphism”.

So, the question is whether such kind of implementation is a code smell and should it always be strictly avoided ? LINQ seems like an obvious choice while looping through collections and creating new objects conditionally. May be its wrong ?

Answer 1

There is a fundemental difference. LINQ is an API that allows you to query collections (as you have demonstrated in your question). A switch (or other conditional) statement is used to control program flow.

The page you are referring to is talking about refactoring code when you have a lot of conditional statements controlling program flow based on some type – in this case it suggests that you may want to replace all the conditionals with some poly-morphism. So in this case there is a code smell. But using conditionals in a LINQ statement is OK – there are probably many ways to structure your LINQ – some will perform better than others, and some will read better than others, but I would not say using conditionals in LINQ is a code smell.