On: Be Careful with Python's New-Style String Format

[Animats]

Internationalization, usually. Word order differs between languages, and this kind of format allows reordering the inserted values.

[zbraniecki → Animats]

Internationalization should never use arbitrary string or system level formatting.

Look at MessageFormat or L20n. Yeah, I know that it's more complex than what you think you need (I've hear the "let's just use JS template literals" so many times) but you actually do.

[Manishearth → Animats]

A lot of folks do use lang format strings for i18n, but they really shouldn't. They won't be able to handle pluralization and other oddities.

[coldtea → Animats]

Yes, but that's meant for trusted translators of the UI, nor arbitrary users, right?

[icebraining → coldtea]

In some applications, users can change the their own translations, which are stored in the DB, to allow for easier customization.

[coldtea → icebraining]

Still, no reason to save them in the platforms native string format and with full reign over native strings.

[azernik → coldtea]

In practice, translators are often externally contracted; the amount of work required to translate any given language is not large enough to make these full-time positions. So only trusted so far.