在try块C#中定义变量

Question

I don't want to have ultra-deep nested blocks, so in cases that variable initialisation could error I would prefer to do it like this:

try
{
    var foo = GetFoo();
}
catch (FooException)
{
   Console.Write(...);
   throw;
}

var bar = GetBar(foo);

Of course it doesn't compile, I'm not allowed to use foo outside of the try-block that initialises it.

Putting a full type specification right above the block also sucks imo:

FooType foo;
try
{
    foo = GetFoo();
}
catch (FooException)
{
   Console.Write(...);
   throw;
}

var bar = GetBar(foo);

Even in less extreme cases like just int foo = 0; already feels dirty, especially with that confusing unused initial value. The catch block exits the program anyway.

How can I try-initialise a variable and use it outside of that scope, with minimal repetition and minimal characters typed?

---

Why I think I dislike the lifted variable declaration solution:

I prefer to avoid typed variable declarations. I dislike repetition. I dislike the disconnect between declaration of the variable and its initialisation. I dislike setting unused initial values. The last two points probably come from a subconscious association with violation of immutability; I tend to like as many variables as possible being conceptually readonly and having separate declaration and initialisation contradicts that pattern.

Answer 1

One way to do this would be putting the initialization logic into another method and wrap it with try / catch there, so then you can have:

var foo = InitializeFoo();
var bar = GetBar(foo);

private Foo InitializeFoo() 
{
     try {
         // initalize and return foo
     }
     catch {
        throw;
     }
}

You can generalize this by passing a delegate to the Initialize method that specifies the initiaze logic and use it for anything else.

public T InitializeVariable<T>(Func<T> initializeAction)
{
     try {
         var x = initializeAction();
         return x;
     }
     catch {
        throw;
     }
}