Plurality in user messages

Question

Many times, when generating messages to show to the user, the message will contain a number of something that I want to inform the customer about.

I\'ll give a

Answer 1

What about what Java has had for years: java.text.MessageFormat and ChoiceFormat? See http://download.oracle.com/javase/1.4.2/docs/api/java/text/MessageFormat.html for more information.

MessageFormat form = new MessageFormat("The disk \"{1}\" contains {0}.");
form.applyPattern(
   "There {0,choice,0#are no files|1#is one file|1<are {0,number,integer} files}.");

Object[] testArgs = {new Long(12373), "MyDisk"};

System.out.println(form.format(testArgs));

// output, with different testArgs
output: The disk "MyDisk" are no files.
output: The disk "MyDisk" is one file.
output: The disk "MyDisk" are 1,273 files.

In your case you want something somewhat simpler:

MessageFormat form = new MessageFormat("Are you sure you want to delete {0,choice,1#one item,1<{0,number.integer} files}?");

The advantage of this approach is that it works well with the i18n bundles, and you can provide translations properly for languages (like Japanese) that have no concept of plural or singular words.

Answer 2

To be able to have pluralized messages which will be possible to localize properly, my opinion is that it would be wise to first create a layer of indirection between the number and a message.

For example, use a constant of some sort to specify which message you want to display. Fetch the message using some function that will hide the implementation details.

get_message(DELETE_WARNING, quantity)

Next, create a dictionary that holds the possible messages and variations, and make variations know when they should be used.

DELETE_WARNING = {
   1: 'Are you sure you want to delete %s item',
   >1: 'Are you sure you want to delete %s items'
   >5: 'My language has special plural above five, do you wish to delete it?'
}

Now you could simply find the key that corresponds to the quantity and interpolate the value of the quantity with that message.

This oversimplified and naive example, but I don't really see any other sane way to do this and be able to provide good support for L10N and I18N.

Answer 3

Do it like it's done in World of Warcraft:

BILLING_NAG_WARNING = "Your play time expires in %d |4minute:minutes;";

Answer 4

For English, plenty of answers above. For other languages it is more difficult, as plurals depend on the gender of the noun and the word ending. Some examples in French:

Regular masculine:

Vous avez choisi 1 compte. Voulez-vous vraiment le supprimer.
Vous avez choisi 2 comptes. Voulez-vous vraiment les supprimer.

Regular feminine

Vous avez choisi 1 table. Voulez-vous vraiment la supprimer.
Vous avez choisi 2 tables. Voulez-vous vraiment les supprimer.

Irregular masculine (finishes with 's')

Vous avez choisi 1 pays. Voulez-vous vraiment le supprimer.
Vous avez choisi 2 pays. Voulez-vous vraiment les supprimer?

The same problem exists in most Latin languages and gets worse in German or Russian, where there are 3 genders (maculine, feminine and neuter).

You'll need to take care if your objective is to handle more than just English.

Answer 5

I depends on how nice a message you want to have. From easiest to hardest:

1. Re-write your error message to avoid pluralization. Not as nice for your user, but faster.

2. Use more general language but still include the number(s).

3. Use a "pluralization" and inflector system ala Rails, so you can say pluralize(5,'bunch') and get 5 bunches. Rails has a good pattern for this.

4. For internationalization, you need to look at what Java provides. That will support a wide variety of languages, including those that have different forms of adjectives with 2 or 3 items. The "s" solution is very English centric.

Which option you go with depends on your product goals. - ndp

Answer 6

You can avoid all of this messy plurality by just deleting the items without any message and giving the user a really good Undo facility. Users never read anything. You should build a good Undo facility as part of your program anyway.

You actually get 2 benefits when you createe a comprehensive Undo facility. The first benefit makes the user's life easier by allowing him/her to reverse mistakes and minimise reading. The second benefit is that your app is reflecting real life by allowing the reversal of non-trivial workflow (not just mistakes).

I once wrote an app without using a single dialog or confirmation message. It took some serious thinking and was significantly harder to implement than using confirmation-type messages. But the end result was rather nice to use according to its end-users.