.
     .
     .
     evaluate first operand
     LOGICAL_AND_1  L
     evaluate second operand
     LOGICAL_AND_2
L:   .
     .
     .

unaryfunc nb_logical_not;
unaryfunc nb_logical_and_1;
unaryfunc nb_logical_or_1;
binaryfunc nb_logical_and_2;
binaryfunc nb_logical_or_2;

PyObject *PyObject_LogicalNot(PyObject *);
PyObject *PyObject_LogicalAnd1(PyObject *);
PyObject *PyObject_LogicalOr1(PyObject *);
PyObject *PyObject_LogicalAnd2(PyObject *, PyObject *);
PyObject *PyObject_LogicalOr2(PyObject *, PyObject *);

if a and b:
    statement1
else:
    statement2

    LOAD_GLOBAL         a
    POP_JUMP_IF_FALSE   false_branch
    LOAD_GLOBAL         b
    POP_JUMP_IF_FALSE   false_branch
    <code for statement1>
    JUMP_FORWARD        end_branch
false_branch:
    <code for statement2>
end_branch:

    LOAD_GLOBAL         a
    LOGICAL_AND_1       test
    LOAD_GLOBAL         b
    LOGICAL_AND_2
test:
    POP_JUMP_IF_FALSE   false_branch
    <code for statement1>
    JUMP_FORWARD        end_branch
false_branch:
    <code for statement2>
end_branch:

    LOAD_GLOBAL         a
    AND1_JUMP           true_branch, false_branch
    LOAD_GLOBAL         b
    AND2_JUMP_IF_FALSE  false_branch
true_branch:
    <code for statement1>
    JUMP_FORWARD        end_branch
false_branch:
    <code for statement2>
end_branch:

#-----------------------------------------------------------------
#
#   This example creates a subclass of numpy array to which
#   'and', 'or' and 'not' can be applied, producing an array
#   of booleans.
#
#-----------------------------------------------------------------

from numpy import array, ndarray

class BArray(ndarray):

    def __str__(self):
        return "barray(%s)" % ndarray.__str__(self)

    def __and2__(self, other):
        return (self & other)

    def __or2__(self, other):
        return (self & other)

    def __not__(self):
        return (self == 0)

def barray(*args, **kwds):
    return array(*args, **kwds).view(type = BArray)

a0 = barray([0, 1, 2, 4])
a1 = barray([1, 2, 3, 4])
a2 = barray([5, 6, 3, 4])
a3 = barray([5, 1, 2, 4])

print "a0:", a0
print "a1:", a1
print "a2:", a2
print "a3:", a3
print "not a0:", not a0
print "a0 == a1 and a2 == a3:", a0 == a1 and a2 == a3
print "a0 == a1 or a2 == a3:", a0 == a1 or a2 == a3

a0: barray([0 1 2 4])
a1: barray([1 2 3 4])
a2: barray([5 6 3 4])
a3: barray([5 1 2 4])
not a0: barray([ True False False False])
a0 == a1 and a2 == a3: barray([False False False  True])
a0 == a1 or a2 == a3: barray([False False False  True])

#-----------------------------------------------------------------
#
#   This example demonstrates the creation of a DSL for database
#   queries allowing 'and' and 'or' operators to be used to
#   formulate the query.
#
#-----------------------------------------------------------------

class SQLNode(object):

    def __and2__(self, other):
        return SQLBinop("and", self, other)

    def __rand2__(self, other):
        return SQLBinop("and", other, self)

    def __eq__(self, other):
        return SQLBinop("=", self, other)


class Table(SQLNode):

    def __init__(self, name):
        self.__tablename__ = name

    def __getattr__(self, name):
        return SQLAttr(self, name)

    def __sql__(self):
        return self.__tablename__


class SQLBinop(SQLNode):

    def __init__(self, op, opnd1, opnd2):
        self.op = op.upper()
        self.opnd1 = opnd1
        self.opnd2 = opnd2

    def __sql__(self):
        return "(%s %s %s)" % (sql(self.opnd1), self.op, sql(self.opnd2))


class SQLAttr(SQLNode):

    def __init__(self, table, name):
        self.table = table
        self.name = name

    def __sql__(self):
        return "%s.%s" % (sql(self.table), self.name)


class SQLSelect(SQLNode):

    def __init__(self, targets):
        self.targets = targets
        self.where_clause = None

    def where(self, expr):
        self.where_clause = expr
        return self

    def __sql__(self):
        result = "SELECT %s" % ", ".join([sql(target) for target in self.targets])
        if self.where_clause:
            result = "%s WHERE %s" % (result, sql(self.where_clause))
        return result


def sql(expr):
    if isinstance(expr, SQLNode):
        return expr.__sql__()
    elif isinstance(expr, str):
        return "'%s'" % expr.replace("'", "''")
    else:
        return str(expr)


def select(*targets):
    return SQLSelect(targets)

#-----------------------------------------------------------------

dishes = Table("dishes")
customers = Table("customers")
orders = Table("orders")

query = select(customers.name, dishes.price, orders.amount).where(
    customers.cust_id == orders.cust_id and orders.dish_id == dishes.dish_id
    and dishes.name == "Spam, Eggs, Sausages and Spam")

print repr(query)
print sql(query)

<__main__.SQLSelect object at 0x1cc830>
SELECT customers.name, dishes.price, orders.amount WHERE
(((customers.cust_id = orders.cust_id) AND (orders.dish_id =
dishes.dish_id)) AND (dishes.name = 'Spam, Eggs, Sausages and Spam'))