Benefits of scoping blocks?

Question

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When do you use code blocks?

Ok, this might be a stupid question and I might be missing something obvious but as I slowly learn C# this has kept nagging me for a while now.

The following code obviously compiles just fine:

public void Foo()
{
    {
        int i = 1;
        i++;
    }

    {
        int i = 1;
        i--;
    }
}

I understand that {} blocks can be used for scoping. The question is why would you want to do this? What problems does this feature solve?

There is no harm that I can see in using them barring that it does add to a more confusing code as these kind of scopes can be more easily overlooked compared those "tied" to flow controls, iterations, etc.

case statements is where its really useful, so you don't get errors for reusing something like `i` in a loop. — Chad, Jan 11 '12 at 18:03

score 6 · Accepted Answer · answered Jan 11 '12 at 18:03

6

It is useful in switch statements where your variable declarations can become confusing:

Confusing code:

switch (true)
{
    case true:
        var msg = "This is true.";
        var copy = msg;
        break;

    case false:
        msg = "This is false.";
        copy = msg;
        break;
}

Clear code:

switch (true)
{
    case true:
    {
        var msg = "This is true.";
        var copy = msg;
        break;
    }

    case false:
    {
        var msg = "This is false.";
        var copy = msg;
        break;
    }
}

answered Jan 11 '12 at 18:03

Devin Burke

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Most fun and stupid when people uses additional line breaks, etc. instead of just bracers/blocks – abatishchev Jan 11 '12 at 18:05
1

Thanks! Lol I've been using them then as I always write `switch` statements the second way. The funny and sad part about it is I thought I was actually using "case blocks" not anonymous blocks...got a lot to learn still :(... – InBetween Jan 11 '12 at 18:09

score 3 · Answer 2 · answered Jan 11 '12 at 18:00

I would say that creating an artificial block for purposes of scoping is often simply confusing, as you note. I've never found a need for it.

If there was some perceived need for it, my guess is refactoring into a separate method is usually a better option.

(note I'm not saying it's absolutely bad. I just think you'd need some really specialized need to have it)

score 1 · Answer 3 · answered Jan 11 '12 at 17:59

1

For 'bare' scoping blocks like these I'd tend to agree with you. From a language design perspective I think that they are a generalization of the implicit scoping blocks in for, while, and if conditions, where they are more important. For example:

foreach (var x in foos) {
    var someMessage = x.ToString();
    doSomething(someMessage);
}

answered Jan 11 '12 at 17:59

Chris Shain

50,833
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I agree completely. This begs the question why it is allowed in the first place...there must be some advantages to this feature. – InBetween Jan 11 '12 at 18:01
@InBetween, conversely, why wouldn't it be allowed? The language allows for `foreach (var x in foos) statement`, where `statement` is a legal statement in code. What's the statement here? A `{ codeblock; }`. We have just established that `{ codeblock; }` is a legal statement. So the question might not then be why allow it, but what is the compelling reason to disallow it. But I haven't bumped my comment here up against the language specification or other resources, so maybe consider this just a bunch of words. – Anthony Pegram Jan 11 '12 at 18:04

score 0 · Answer 4 · answered Jan 11 '12 at 17:59

0

The quick answer is it keeps you from inadvertently changing a variable in an unexpected way. By having it "in scope" you can act on it only when you want to and not "accidentally" change the value

answered Jan 11 '12 at 17:59

Brian

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Benefits of scoping blocks?

4 Answers4