... now that we have fancy new type unification:

from _py_htmltext import _format_re, _wraparg, _DictWrapper, _escape_string
from types import TupleType

class htmltext(str):
    def __repr__(self):
        return '' % str.__repr__(self)
        # or use super(), but there's no benefit since 'str' is not complicated
        return '' % super(str, self).__repr__()

    def __mod__(self, args):
        codes = []
        usedict = 0
        for format in _format_re.findall(self):
            if format[-1] != '%':
                if format[1] == '(':
                    usedict = 1
                codes.append(format[-1])
        if usedict:
            args = _DictWrapper(args)
        else:
            if len(codes) == 1 and not isinstance(args, TupleType):
                args = (args,)
            args = tuple([_wraparg(arg) for arg in args])
        return self.__class__(str.__mod__(self, args))
    def __add__(self, other):
        if isinstance(other, str):
            return self.__class__(str.__add__(self, _escape_str(other)))
        else:
            return NotImplemented
    def __radd__(self, other):
        if isinstance(other, str):
            return self.__class__(str.__add__(_escape_str(other), self))
        else:
            return NotImplemented
    def join(self, items):
        quoted_items = []
        for item in items:
            if isinstance(item, str):
                quoted_items.append(_escape_str(item))
            else:
                raise TypeError(
                    'join() requires string arguments (got %r)' % item)
        return self.__class__(str.join(self, quoted_items))
    def startswith(self, s):
        return str.startswith(self, _escape_str(s))
    # ...

def _escape_str(s):
    if isinstance(s, htmltext):
        return str(s)
    else:
        return _escape_string(s)




I'm sure the new "subtype" C API would allow the same to be written in C.
This htmltext *can* be used where a string is expected.

But I'm sure you guys already thought of it and rejected it.  How come?