Re: How about a Hash template?

[Andrei Alexandrescu]

On 4/29/11 8:50 AM, Denis Koroskin wrote:

On Thu, 28 Apr 2011 03:10:15 +0400, Andrej Mitrovic
<andrej.mitrov...@gmail.com> wrote:

I often see code written like this:

if (value == somevalue ||
value == someothervalue ||
value == yetanothervalue);

You could use the switch statement. But that introduces indentation,
and is rarely used for a couple of values.

I really like the "in" keyword, and I also like hashes since they can
potentially speed up look-ups compared to conventional arrays. So I
thought it would be cool to have a Hash template that constructs an
associative array which you can use especially in if statements when
you just want to know if a runtime value matches some predetermined
value.

Here's my attempt at writing it:
http://codepad.org/c4sYDSyR

Whaddya think?

Try this:

[snip]

Nice work. I think this code could earn a place in Phobos:

auto either(Keys...)(Keys keys)
{
    static struct Result
    {
        bool opIn_r(Key)(Key key)
        {
            foreach (k; keys) {
                if (k == key) {
                    return true;
                }
            }
            return false;
        }
        private Keys keys;
    }
    return Result(keys);
}


Andrei