[Issue 11070] Allow auto statement in a switch statement

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=11070


bearophile_hugs at eml.cc changed:

           What    |Removed                     |Added
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                 CC|                            |bearophile_hugs at eml.cc


--- Comment #1 from bearophile_hugs at eml.cc 2013-09-19 13:16:07 PDT ---
(In reply to comment #0)
> Additionally, such a variable
> shouldn't be visible outside the switch statement if it's only going to be used
> inside of the switch statement.

That's easy solved:

auto get() { return "c"; }

void main() {
    import std.string;

    {
        auto res = get;
        switch (res) {
            case "a": break;
            case "b": break;
            default:  assert(0, format("Unhandled case: '%s'", res));
        }
    }

    // res not visible here.
}



> This will also eliminate the need for code duplication in switch statements
> which use a common label statement, for example:
> 
> -----
> import std.string;
> import std.stdio;
> 
> auto get() { return "d"; }
> 
> void main()
> {
>     switch (auto res = get())
>     {
>         case "a": goto common;
>         case "b": goto common;
>         case "c": goto common;
> 
>         common:
>             writefln("Got result: %s", res);
>             break;
> 
>         default:  assert(0, format("Unhandled case: '%s'", res));
>     }
> }


Usually common bodies for case statements are not a big problem in D:

auto get() { return "d"; }

void main() {
    import std.stdio, std.string;

    {
        auto res = get;
        switch (res) {
            case "a", "b", "c":
                writefln("Got result: %s", res);
                break;
            default:
                assert(0, format("Unhandled case: '%s'", res));
        }
    }

    // res not visible here.
}

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