Function _determine_attrs_eq_order

src/attr/_make.py:1228–1253

Validate the combination of *cmp*, *eq*, and *order*. Derive the effective values of eq and order. If *eq* is None, set it to *default_eq*.

(cmp, eq, order, default_eq)

def _determine_attrs_eq_order(cmp, eq, order, default_eq):
    """
    Validate the combination of *cmp*, *eq*, and *order*. Derive the effective
    values of eq and order.  If *eq* is None, set it to *default_eq*.
    """
    if cmp is not None and any((eq is not None, order is not None)):
        msg = "Don't mix `cmp` with `eq' and `order`."
        raise ValueError(msg)

    # cmp takes precedence due to bw-compatibility.
    if cmp is not None:
        return cmp, cmp

    # If left None, equality is set to the specified default and ordering
    # mirrors equality.
    if eq is None:
        eq = default_eq

    if order is None:
        order = eq

    if eq is False and order is True:
        msg = "`order` can only be True if `eq` is True too."
        raise ValueError(msg)

    return eq, order


def _determine_attrib_eq_order(cmp, eq, order, default_eq):