namespace System.Configuration { [AttributeUsage(AttributeTargets.Property)] public class ConfigurationValidatorAttribute : Attribute { internal Type _declaringType; public virtual ConfigurationValidatorBase ValidatorInstance => (ConfigurationValidatorBase)TypeUtil.CreateInstance(ValidatorType); public Type ValidatorType { get; } protected ConfigurationValidatorAttribute() { } public ConfigurationValidatorAttribute(Type validator) { if (validator == (Type)null) throw new ArgumentNullException("validator"); if (!typeof(ConfigurationValidatorBase).IsAssignableFrom(validator)) throw new ArgumentException(System.SR.Format(System.SR.Validator_Attribute_param_not_validator, "ConfigurationValidatorBase")); ValidatorType = validator; } internal void SetDeclaringType(Type declaringType) { if (!(declaringType == (Type)null) && _declaringType == (Type)null) _declaringType = declaringType; } } }