[Translation] Document range translation using the ICU MessageFormat

[kevin-verschaeve]

The ICU MessageFormatter has a notation to do the same as transchoice was able to, concerning ranges.

I think this would be a good idea to document it on the Symfony docs because :

• it is not really easy to find and understand it on the ICU intl documentation.
• one can think that using ranges like ]-INF,0] my translation is no more possible with ICU if it is not documented here

I don't know if my examples are good enough or well explained, so please, don't hesitate to reword me.

Thanks

[Pierstoval]

Slight changes, nothing big :)

[kevin-verschaeve]

I changed the target branch to 4.2 as ICU was introduced in 4.2

[wouterj]

Hi @kevin-verschaeve! First of all, thanks for submitting these docs to help further readers!

I'm however not so sure if we should recommend or document the choice format. The reason is that it seems to be deprecated/discouraged by the main MessageFormat implementations:

Use of the old "choice" argument type is discouraged. It cannot handle plural rules for many languages, and is clumsy for simple selection.
-- http://userguide.icu-project.org/formatparse/messages

Note that choiceformat is considered deprecated and pluralformat and selectformat are favored.
-- https://help.smartling.com/hc/en-us/articles/360008030994-ICU-Message-Format

Messageformat supports and extends all parts of the standard, with the exception of the deprecated ChoiceFormat.
-- https://messageformat.github.io/messageformat/

---

I've been trying and looking to find another way to do this using MessageFormat's plural and select formats, but failed to find something. I think the main idea is to not combine logic and i18n. The supported formats (select & plural) are ways to modify the same message based on variables. Logic like "You don't have money" or "You have lots of money" are logic things, things that should be encapsulated in real code instead of letting your translator decide on such domain specific decisions.

So instead of:

// balance_message: '{balance, choice, -∞ < Oops! I'm down | 0 < I still have money | 1000 # I have a lot of money !}';

$message = $translator->trans('balance_message', $balance);

You should use:

// no_money_message: Oops! I'm down
// some_money_message: I still have money
// lots_of_money_message: I have a lot of money

if ($balance < 0) {
    $message = $translator->trans('no_money_message');
} elseif ($balance < 1000) {
    $message = $translator->trans('some_money_message');
} else {
    $message = $translator->trans('lots_of_money_message');
}

---

As the old range format used by Symfony allowed you to put domain logic in the message strings, what do you think about replacing this choice chapter with a small .. trip:: box that describes it's discouraged to put logic in the message formats and that you should use PHP code instead for this logic?

[kevin-verschaeve]

Hi @wouterj,

Thanks for your feedback !

Indeed, I did not see that the choice format was deprecated.

So, I agree with you, it would not be a great idea to add something deprecated into the documentation.

However, I am sad that such a thing is not possible. I liked the way we used translations for this kind of logic, but that's my humble opinion.

I will add the tip box as you suggered.

[wouterj]

Thanks again @kevin-verschaeve!

Now Symfony 5 is released, I've gone ahead and merged this PR. Afterwards, I reverted your changes and added the tip: 2baeb1c This way, you still get the credits you deserve!

As Symfony 4.2 has reached end of maintanaince some time ago, I've merged this in 4.3 and up.

#SymfonyHackathon