Visual Studio 2019 recommended converting a switch statement I had written to a switch expression (both included below for context).
For a simple example such as this, is there any technical or performance advantage to writing it as an expression? Do the two versions compile differently for example?
Statement
switch(reason)
{
case Reasons.Case1: return "string1";
case Reasons.Case2: return "string2";
default: throw new ArgumentException("Invalid argument");
}
Expression
return reason switch {
Reasons.Case1 => "string1",
Reasons.Case2 => "string2",
_ => throw new ArgumentException("Invalid argument")
};
In the example you give there's not a lot in it really. However, switch expressions are useful for declaring and initializing variables in one step. For example:
var description = reason switch
{
Reasons.Case1 => "string1",
Reasons.Case2 => "string2",
_ => throw new ArgumentException("Invalid argument")
};
Here we can declare and initialize description
immediately. If we used a switch statement we'd have to say something like this:
string description = null;
switch(reason)
{
case Reasons.Case1: description = "string1";
break;
case Reasons.Case2: description = "string2";
break;
default: throw new ArgumentException("Invalid argument");
}
One downside of switch expressions at the moment (in VS2019 at least) is that you can't set a breakpoint on an individual condition, only the whole expression. However, with switch statements you can set a breakpoint on an individual case statement.