MaL> If you want a fail-safe stringified version of a Unicode object,
MaL> your only choice is to create a new API that does error checking,
MaL> properly clears the error and then returns a reference to a constant
MaL> string, e.g. "<repr-error>".

I wrote a function _PyUnicode_AsStringOrDefault(unicode, default_str) which call _PyUnicode_AsStringAndSize() and return the default_str on error. It can be used in error handler (places where you don't really like to reraise new error) or if you don't care about (unicode) errors.