Re: Relational metamethods and mixed types
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- Subject: Re: Relational metamethods and mixed types
- From: David Manura <dm.lua@...>
- Date: 2009年3月23日 22:51:58 -0400
On Mon, Mar 23, 2009 at 10:02 PM, Geoff Leyland wrote:
> On 24/03/2009, at 2:19 PM, David Manura wrote:
>> Here's a few alternatives:
>>
>> a_constraint = le(2 * x1 + 3 * x2 + 4 * x3, 6)
>> a_constraint = (2 * x1 + 3 * x2 + 4 * x3):le(6)
>> a_constraint = Constraint[[2 * x1 + 3 * x2 + 4 * x3 <= 6]]
Also,
a_constraint = expr(2 * x1 + 3 * x2 + 4 * x3, '<=', 6)
a_constraint = (2 * x1 + 3 * x2 + 4 * x3) '<=' (6)
a_constraint:add(2 * x1 + 3 * x2 + 4 * x3, '<=', 6)
a_constraint(2 * x1 + 3 * x2 + 4 * x3, '<=', 6)
and, if even worth mentioning,
local val
local mt = {}
function mt.__le(a,b) val = {'<=', a, b} end
function mt.__tostring(a) return tostring(a.n) end
local function C(n) return setmetatable({n=n}, mt) end
local function compare(...) return val end
local y = compare(C(2) <= C(3))
> Pulp[1] and pyomo[2] manage quite nicely in Python
since Python allows this:
class A(object):
def __init__(self, foo):
self.foo = foo
def __le__(self, other):
return 'works!'
print ( A(1) <= A(2) ) # print 'works!'