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Question

I'm not sure what the correct name for it is (and thus how to search for it), but I was just looking through some go code and saw it organized with statements inside of {}'s. I'm wondering what the reason is for supporting grouping statements like this?

The code looks like this:

// Check horizontal
{
    left_to_win := 3

    stop_1 := false
    stop_2 := false
    for x := 1; x <= 4; x++ {
        // ....
    }
}

// Check vertical
{
    left_to_win := 3

    stop_1 := false
    stop_2 := false

    for x := 1; x <= 4; x++ {
        // ...
    }
}

// Check diagonal bottom to top
{
    left_to_win := 3

    stop_1 := false
    stop_2 := false

    for x := 1; x <= 4; x++ {
        // ...
    }
}

In the specific example it seems like it could easily be refactored into a single utility function. What's the name of this feature, and are there any good examples of times to use it?

Answer 1

Those braces are defining a more specific scope for local variables. In your case each scope is declaring stop_1, stop_2 and left_to_win. Without the additional curly braces you would get a compiler error saying you're redeclaring or defining those variables since you're using the short hand := which declares and assigns in one statement.In this case the code could be written to instead just use := on the initial declaration and then = for subsequent assignment which would remove the need for those scopes defined by the curly braces.

See here for more details.