A doubt with the ICloneable interface in petshop 4.0?

Question

In the 'DBUtility' project of Petshop 4.0,the abstract class SqlHelper has a method 'GetCachedParameters':

        public static SqlParameter[] GetCachedParameters(string cacheKey) {
        SqlParameter[] cachedParms = (SqlParameter[])parmCache[cacheKey];

        if (cachedParms == null)
            return null;

        SqlParameter[] clonedParms = new SqlParameter[cachedParms.Length];

        for (int i = 0, j = cachedParms.Length; i < j; i++)
            clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();

        return clonedParms;
    }

why not return the 'cachedParms' directly ?

Answer 1

If cachedParms were returned directly, the caller could then change the elements of the array. The contents of the cache would then be effectively corrupted - the next caller to fetch the parameters from the cache with the same cache key would get unexpected results.

EDIT: Cloning the array itself prevents the elements being replaced with different parameters. Cloning the elements as well prevents the parameter objects being mutated. Basically it's all defensive coding.