Code Contract (Java and C# Cross Reference Guide)

A.k.a. Class Contract and Design by Contracts.

A contract with a method that must be true upon calling (pre) or exiting (post). A pre-condition contract must be true when the method is called. A post-condition contract must be true when exiting. If either are not true, an error is raised. For example, you can use code contracts to check for the validity of input parameters, and results

An invariant is also a code contract which validates the state of the object required by the method.

[Not specified yet. Coming...]

C#:  "Code Contracts" Not Supported Although not currently supported, there are plans for the next version of VS.Net and .Net using Requires and Ensures keywords. Look for code contracts in VS.Net 2010 and .Net 4. Read About It: Introduction to Code Contracts If you code with VS.Net 2008 Pro or above and wish to implement contracts now, checkout the following download: Managed Contract Tools   Syntax Example: //Future syntax may look something like: string SetAge(int pAge) { Contract.Requires(pAge>0); } string GetAge() { Contract.Ensures(Contract.Result() != null); }