Question

Where is the proper place to perform validation given the following scenario/code below:

In MethodA only: since this is the public method which is meant to be used by external assemblies? In MethodA and B since both these can be accessed outside the class? Or Methods A, B and C since method C may be used by another internal method (but it might not efficient since the programmer can see the code for MethodC already and therefore should be able to know the valid parameters to pass)?

Thanks for any input.

public class A   {          public void MethodA(param)       {            MethodB(param);       }        internal void MethodB(param)     {           MethodC(param);     }      private void MethodC(param)     {     } } 

Answer 1

Parameter validation should always be performed regardless of the caller’s location (inside or outside of the assembly). Defensive programming, one can say.