'C{dirdbm[k] = v}
Create or modify a textfile in this directory
@type k: bytes
@param k: key to set
@type v: bytes
@param v: value to associate with C{k}'

def __setitem__(self, k, v):

    if (not (type(k) == bytes)):
        raise TypeError('DirDBM    key    must    be    bytes')
    if (not (type(v) == bytes)):
        raise TypeError('DirDBM    value    must    be    bytes')
    k = self._encode(k)
    old = self._dnamePath.child(k)
    if old.exists():
        new = old.siblingExtension('.rpl')
    else:
        new = old.siblingExtension('.new')
    try:
        self._writeFile(new, v)
    except:
        new.remove()
        raise
    else:
        if old.exists():
            old.remove()
        new.moveTo(old)
