The first parameter of formattedRead is a non-const ref. Is there
a good reason for this?

e.g. the below doesn't compile, but if I remove the 'const' from Foo.normalize, then it succeeds:

unittest {
    import std.datetime;
    struct Foo {
        string date;
        DateTime normalize() const {
            import std.format, std.exception;
            int month, day, year;
            enforce(3 == formattedRead(date, "%d/%d/%d", &month, &day, &year));
            return DateTime(year, month, day, 0, 0, 0);
        }
    }

    Foo foo = Foo("12/2/2014");
    assert(foo.normalize == DateTime(2014, 12, 2, 0, 0, 0));
}

On Friday, 29 August 2014 at 04:21:54 UTC, Andrew Godfrey wrote:
> The first parameter of formattedRead is a non-const ref. Is there
> a good reason for this?

formattedRead takes an input range as the first parameter, and consumes it as it is going through the format string. On exit, the range will contain the remainder of the initial range after all fields have been read and parsed.

const(char)[] tmp = date;
enforce(3 == formattedRead(tmp, "%d/%d/%d", &month,
&day, &year));

On Friday, 29 August 2014 at 04:29:31 UTC, Vladimir Panteleev wrote:
> On Friday, 29 August 2014 at 04:21:54 UTC, Andrew Godfrey wrote:
>> The first parameter of formattedRead is a non-const ref. Is there
>> a good reason for this?
>
> formattedRead takes an input range as the first parameter, and consumes it as it is going through the format string. On exit, the range will contain the remainder of the initial range after all fields have been read and parsed.

Ah, thanks! I should have posted this in D.learn, sorry.