import codecs
def encoder(s, errors="strict"):
    raise RuntimeError("dummy error")

def decoder(s, errors="strict"):
    return unicode(s, 'ascii', errors), len(s)
        

def dmy_search(encoding):
    if encoding == "dmyencoding":
        return (encoder, decoder, codecs.StreamWriter, codecs.StreamReader)

def test():
    codecs.register(dmy_search)
    src = """#! -*- coding: dmyencoding -*-\n
print 'hello
"""
    compile(src, "", "exec")

test()