QObject::tr() not translating dynamically generated strings

Question

QObject::tr("%1").arg(_value);

Here _value is of QString type, which is dynamically generated. Is the above way correct to translate dynamically generated strings as in my code it doesn't seem to work.

Answer 1

There are two steps:

1. Make Qt extract the strings for translation.

This means using one of

• tr() in a QObject subclass
• QCoreApplication::translate()
• QT_TR_NOOP / QT_TRANSLATE_NOOP

lupdate will extract the strings passed to those functions/macros, and make them available to linguist for translation.

2. Performing the translation (i.e. the "lookup")

This is again done by tr() and QCoreApplication::translate(). So for instance:

// marking the strings for extraction
static const char *strings[] = { 
    QT_TRANSLATE_NOOP("MyContext", "hello"), 
    QT_TRANSLATE_NOOP("MyContext", "world"); 
};
// performing the translation at runtime
qApp->translate("MyContext", strings[0]);

There's a ton of documentation about the whole process, see here.