A writable collection property can be replaced by a completely different collection. Making it readonly prevents that while still
allowing individual members to be set. If you want to allow the replacement of the whole collection the recommended pattern is to implement a method
to remove all the elements (e.g. System.Collections.List<T>.Clear) and a method to populate the collection (e.g.
System.Collections.List<T>.AddRange).
This rule raises an issue when an externally visible writable property is of a type that implements System.Collections.ICollection or
System.Collections.Generic.ICollection<T>.
Noncompliant code example
using System;
using System.Collections;
namespace MyLibrary
{
public class Foo
{
List<string> strings;
public List<string> SomeStrings
{
get { return strings; }
set { strings = value; } // Noncompliant
}
}
}
Compliant solution
using System;
using System.Collections;
namespace MyLibrary
{
public class Foo
{
List<string> strings;
public List<string> SomeStrings
{
get { return strings; }
}
}
}
Exceptions
This rule does not raise issues for
-
string, Array and PermissionSet,
- properties marked as
DataMemberAttribute
- classes marked as
Serializable
- properties overriding a base class member
- properties implementing interface
