C# code contract: how to check associativity

hi,

i'm trying encode associativity of binary operation code contract.

below atempt far. sensible way ?

    public interface imagma<telem>
        telem : iequatable<telem>
    {
        [pure]
        telem mult(telem a, telem b);
    }

    public interface iassociativemagma<telem> :
        imagma<telem>
        telem : iequatable<telem>
    {

    }

    [contractclassfor(typeof(iassociativemagma<>))]     // can't put telem here
    internal abstract class associativemagmacontract<telem> :
        iassociativemagma<telem>
        telem : iequatable<telem>
    {
        [pure]
        public telem mult(telem a, telem b)
        {
            return default(telem);
        }

        [contractinvariantmethod]
        private void associativityproperty(telem a, telem b, telem c)      // complains that
        {
            // var = contract.any<telem>(); // idea
            contract.invariant(mult(mult(a, b), c).equals(mult(a, mult(b, c))));
        }
    }

    public class myassociativemagma : iassociativemagma<int>
    {
        [pure]
        public int mult(int a, int b)
        {
            return + b;
        }
    }

hi kikipoi,

thank posting here.

for question, refer msdn article code contracts.

in article, has explanation of specify preconditions, postconditions, , object invariants in code.

• preconditions requirements must met when entering method or property.
• postconditions describe expectations @ time method or property code exits.
• object invariants describe expected state class in state.

i hope helpful you.

best regards,

wendy

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