When should I use a contains method instead of logical operators in a c# if statement?

Question

My colleague said I should be using an array.contains() in my if statements when evaluating enums.

example a:

if (new[] { enumvalue.a, enumvalue.b, enumvalue.c }.Contains(x.some_enum_value))
{
    do_something();
}

...vs example b:

if (x.some_enum_value == enumvalue.a || x.some_enum_value == enumvalue.b || x.some_enum_value == enumvalue.c) 
{
    do_something();
}

When should I use example a over example b?

Answer 1

Best of both worlds using enum constraint in C# 7.3:

public static bool IsIn<TEnum>(this TEnum source, params TEnum[] list)
   where TEnum : Enum 
   => list.Contains(source);

or if you will:

public static bool IsIn<T>(this T source, params T[] list)
   => list.Contains(source);

Usage:

var someEnum = MyEnum.Three;

if (someEnum.IsIn(MyEnum.One, MyEnum.Three))
{
   Console.WriteLine();
}

var list = new[]
              {
                 MyEnum.Three,
                 MyEnum.One
              };

if (someEnum.IsIn(list))
{
   Console.WriteLine();
}

Note : in short, you should do what you like the most, and what's most maintainable, and also what your boss likes. Everything else is subjective.

Note 2 : The only advantage is the extension method usage, and it can take a list of parameters using the params keyword. Otherwise, there is not much value in this.