Suppose I have this code:
int a = 1;
int b = 2;
string s = (a + b == 3 ? "3" : array[a + b]);
I would like to declare a "local" variable to store (a+b) so that I don't need to compute it twice. I imagine something like that:
int a = 1;
int b = 2;
string s = (c == 3 ? "3" : array[c]) where c = a + b;
//from now on, c doesn't exist anymore
I know where doesn't exist. I tried to use using var c = a + b but I don't think it's possible. Is there a way?
What you want to do reminds me of Kotlin's scope functions, specifically let. You can write an extension method for this:
static class ScopeFunctions
{
public static U Let<T, U>(this T x, Func<T, U> func) => func(x);
}
Usage:
string s = (a + b).Let(x =>
(x == 3 ? "3" : array[x])
);
x becomes the "'local' variable to store (a+b) so that I don't need to compute it twice" that you "discard right after", as x will be out of scope outside the lambda.