Pluralization

Plurals are also elegantly handled when using wuchale. You still don’t write code just for the sake of internationalization, but for reusability. Your code still works without wuchale.

Usage

You first define your own function that selects the correct message from provided candidates based on the number, replaces the placeholder if needed, and returns the final message. The only requirement is that the signature has to match that of the below example.

src/utils.js

export function plural(num, candidates, rule = n => n === 1 ? 0 : 1) {
    const index = rule(num)
    return candidates[index].replace('#', num)
}

Notice that this is still not about wuchale, you are just defining a convenient reusable function with pluggable selection rules.

To be more specific, the signature has to be:

function plural(num: number, candidates: string[], rule?: (n: number) => number): string

Now you use your function in your codebase:

<script>
    import {plural} from '/src/utils.js'
    let itemCount = 5
</script>

<p>{plural(itemCount, ['One item', '# items'])}</p>

That’s it. wuchale has enough information to take it from there.

How it works

The first information it takes is from your locale configuration in wuchale.config.js. It takes the number of plurals, nPlurals and prepares the translation catalogs in this way (e.g. Spanish, after translation):

es.po

msgid "One item"
msgid_plural "# items"
msgstr[0] "Un artículo"
msgstr[1] "# artículos"

The next information it takes from the config is the plural rule. It bundles that with the data when it compiles the catalogs.

es.compiled.js

export const c = [['Un artículo', '# artículos']]
export const p = n => n == 1 ? 0 : 1

There are only two plural forms because Spanish has two. Some languages have more, and they are supported too, it’s just a matter of having the correct nPlurals and explaining the rule using the plural expression in the config and wuchale prepares the the catalogs and compiles them accordingly.

Then during transformation, your code gets updated to use the current locale’s data:

<script>
    import _w_rt_ from '../locales/loader.svelte.js'
    const _w_runtime_ = _w_rt_('main')
    import {plural} from '/src/utils.js'
    let itemCount = 5
</script>

<p>{plural(itemCount, _w_runtime_.tp(0), _w_runtime_._.p)}</p>

That way, the function that you define doesn’t have to know about the number of possible plural rules; it is provided the candidates and the selection rule specific to the locale. It just have to select the candidate, do the necessary modification (replacing # for example) and return the resulting single string.

You can configure wuchale to work with a function with a different name if you want.