52 lines
1.5 KiB
Plaintext
52 lines
1.5 KiB
Plaintext
When you implement ``IComparable`` or ``IComparable<T>`` on a class you should also override ``Equals(object)`` and overload the comparison operators (``==``, ``!=``, ``<``, ``<=``, ``>``, ``>=``). That's because the CLR cannot automatically call your ``CompareTo`` implementation from ``Equals(object)`` or from the base comparison operator implementations. Additionally, it is best practice to override ``GetHashCode`` along with ``Equals``.
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This rule raises an issue when a class implements ``IComparable`` without also overriding ``Equals(object)`` and the comparison operators.
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== Noncompliant Code Example
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----
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public class Foo: IComparable // Noncompliant
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{
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public int CompareTo(object obj) { /* ... */ }
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}
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----
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== Compliant Solution
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----
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public class Foo: IComparable
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{
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public int CompareTo(object obj) { /* ... */ }
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public override bool Equals(object obj)
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{
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var other = obj as Foo;
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if (object.ReferenceEquals(other, null))
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{
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return false;
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}
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return this.CompareTo(other) == 0;
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}
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public int GetHashCode() { /* ... */ }
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public static bool operator == (Foo left, Foo right)
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{
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if (object.ReferenceEquals(left, null))
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{
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return object.ReferenceEquals(right, null);
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}
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return left.Equals(right);
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}
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public static bool operator > (Foo left, Foo right)
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{
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return Compare(left, right) > 0;
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}
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public static bool operator < (Foo left, Foo right)
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{
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return Compare(left, right) < 0;
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}
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public static bool operator != (Foo left, Foo right)
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{
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return !(left == right);
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}
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}
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----
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