Migration to Unicode

This is a summary of the recommendations for adapting applications to handle Unicode. Although some recommendations can be applied in earlier version of EiffelStudio starting from 5.6, the following recommendations are made for 7.2 and higher.

General rule

1. Never use STRING_8 or any variant of it unless you write a program that is going to be deleted in 5 minutes after running it. Do not even consider using STRING_8 or its variant. Always use IMMUTABLE_STRING_32, READABLE_STRING_32 or STRING_32.
2. Do not use classes from third-party libraries that take STRING_8 rather than STRING_32.
3. Use PATH to manipulate file or directory names
4. Whenever an API takes a READABLE_STRING_GENERAL argument, assume that STRING_8 will be treated as Unicode strings in the range 0 .. 255, unless explicitly noted.

Temporary solution

1. Replace types using the following table:

1. Consider using READABLE_STRING_32 for argument types. If you cannot immediately change argument types to take READABLE_STRING_32, e.g. because this is a library class, use READABLE_STRING_GENERAL and perform all the necessary conversions inside the routine.
2. If you need to convert one UTF encoding into another one, use UTF_CONVERTER. This is an expanded class, so it's possible to declare a local variable of this type and call features on it without explicit object creation.