Contract.Requires<TException> Method (Boolean, String)
Specifies a precondition contract for the enclosing method or property, and throws an exception with the provided message if the condition for the contract fails.
Assemblies: mscorlib (in mscorlib.dll)
System.Diagnostics.Contracts (in System.Diagnostics.Contracts.dll)
public static void Requires<TException>( bool condition, string userMessage ) where TException : Exception
The exception to throw if the condition is false.
You must turn on run-time checking to use the Requires method. If run-time checking is turned off, the process will be terminated. To obtain the tools for runtime checking, see Code Contracts on the MSDN DevLabs Web site.
This method call must be at the beginning of a method or property, before any other code.
This contract is exposed to clients; therefore, it must only reference members that are at least as visible as the enclosing method.
Use this method instead of the Contract.Requires(Boolean, String) method when you want to throw an exception if the precondition fails.