Negative plurals

[karljj1]

Hi,

I have noticed that if we use a negative value in a plural, the behaviour is different.
For example, -1 will produce a different result than 1 when using the English plural:

I have {0:plural:{} apple|{} apples}

1 = I have 1 apple
-1 = I have -1 apples

Are there situations where a negative plural will be different, or should we Math.Abs them before we evaluate the plural?

[axunonb]

Good question. The apple example suggests using the absolute value. It is different if we want to express a delta, such as:
Change in inventory: {0:plural:{} item|{} items}
-4 = Change in inventory: -4 items
1 = Change in inventory:: 1 item

[karljj1]

Yes! Is this something that could be solved by checking for -1 and converting to 1, or are there other use cases where a negative plural is different from a positive?

[axunonb]

Hm, it's tricky. After all I think the following should be the correct implementation for all DualOneOther languages.
[Edited]

private static PluralRuleDelegate DualOneOther => (value, pluralWordsCount) =>
{
    return pluralWordsCount switch
    {
        2 => (value is 1 or -1) ? 0 : 1,
        3 => value switch
        {
            0 => 0,
            1 or -1 => 1,
            _ => 2
        },
        4 => value < 0 ? 0 : value == 0 ? 1 : value is 1 or -1 ? 2 : 3,
        _ => -1
    };
};

The test cases that will be failing with this change obviously have wrong expected values (Test_Default, Test_English, Test_Turkish).
E.g.: Expected: "There are -1 items remaining". But was: "There is -1 item remaining". That's exactly the case you pointed out.

[karljj1]

Do you think this change should also be made for other languages that have a singular?

[axunonb]

Yes, I think for all languages having DualOneOther as the PluralRuleDelegate the rule for 1 and -1 would apply.

[axunonb]

There is a certain risk with this change. We have to mention this in the release notes.

[axunonb]

See further discussion in issue #503