c# - Putting Contracts for Constructor Arguments -

assume have interface follows contract class

[contractclassfor(typeof(custom))] public abstract class customcontract : custom {     public string getperson(int i)     {         contract.requires(i > 0);         contract.ensures(!string.isnullorempty(contract.result<string>()));         return default(string);     }     public string name { get; set; } }  [contractclass(typeof(customcontract))]     public interface custom     {         string getperson(int i);         string name { get; set; }     } 

implementation like

    public class customprocessor: custom     {          public customprocessor(isomeinterface obj, string logname)          {               if(null == obj) throw new argumentnullexception(...);                ...          }          public getperson(int i)          {              ...          }      } 

does make sense replace throw new argumentnullexception in constructor contract.requires(obj != null).

contracts supposed defined interface , since constructor part of implementation , not interface leaned towards current approach. practice ?

to out of code contracts, yes, makes sense replace argumentnullexception throws contract.requires.

this right given fact you're using interface , contract class. there no other place validate constructor parameters other in constructor itself.

if use argumentnullexception approach you'll miss out on code contract's static checking , other goodies.