76 lines
1.7 KiB
Plaintext
76 lines
1.7 KiB
Plaintext
``++object.Equals()++`` overrides can be optimized by checking first for reference equality between ``++this++`` and the parameter. This check can be implemented by calling ``++object.ReferenceEquals()++`` or ``++base.Equals()++``, where ``++base++`` is ``++object++``. However, using ``++base.Equals()++`` is a maintenance hazard because while it works if you extend ``++Object++`` directly, if you introduce a new base class that overrides ``++Equals++``, it suddenly stops working.
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This rule raises an issue if ``++base.Equals()++`` is used but ``++base++`` is not ``++object++``.
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== Noncompliant Code Example
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----
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class Base
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{
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private int baseField;
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public override bool Equals(object other)
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{
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if (base.Equals(other)) // Okay; base is object
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{
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return true;
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}
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return this.baseField == ((Base)other).baseField;
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}
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}
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class Derived : Base
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{
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private int derivedField;
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public override bool Equals(object other)
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{
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if (base.Equals(other)) // Noncompliant
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{
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return true;
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}
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return this.derivedField == ((Derived)other).derivedField;
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}
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}
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----
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== Compliant Solution
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----
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class Base
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{
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private int baseField;
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public override bool Equals(object other)
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{
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if (object.ReferenceEquals(this, other)) // base.Equals is okay here, but object.ReferenceEquals is better
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{
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return true;
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}
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return this.baseField == ((Base)other).baseField;
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}
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}
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class Derived : Base
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{
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private int derivedField;
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public override bool Equals(object other)
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{
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if (object.ReferenceEquals(this, other))
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{
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return true;
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}
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return base.Equals(other) && this.derivedField == ((Derived)other).derivedField;
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}
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}
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----
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