How does string formats '%' operator is implemented in CPython 2.7?
Can't find any reference in the Python documentation.
Well, I fact I found the topic: String conversion and formatting, for
The implementation is in the PyString_Format that is called by the string_mod function in Objects/stringobject.c. The latter in turn is a slot method stored in PyString_Type->tp_as_number->nb_remainder.
The functions PyOS_*snprintf are not really related to the implementation of str.__mod__.