Am I implementing this simple contract incorrectly?

Question

This is my code:

public class RegularPolygon
{
    public int VertexCount;
    public double SideLength;

    public RegularPolygon(int vertexCount, double sideL         


        

Answer 1

First thing to check - have you actually got contract checking turned on? If not, none of your contracts will do anything. That would explain the R# warning, too. Look under "Code Contracts" in the build properties, and see what it says under "Runtime Checking".

As per comments, ensure you have CONTRACTS_FULL defined as a compilation symbol - that appears to be what R# requires.

Second point: you've got public mutable fields, which means your invariant can be violated at any moment by someone writing

polygon.VertexCount = 0;

Please don't use public fields, particularly not writable ones. :)