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Code inspection: Cast expression can be replaced with explicit variable type

C-style cast expression in C# can be both a static upcast and a dynamic downcast, both having the same syntax. Without keeping the type hierarchies in mind, there is no way to tell if the cast is a safe upcast or a runtime downcast. Moreover, a static upcast can be accidentally turned into a dynamic downcast during a refactoring. To avoid these problems and make code less fragile, this inspection suggests using an explicit type instead of the cast where possible.

interface IBase; interface IDerived : IBase; class Derived : IDerived; class Sample { public Sample() { var derivedInstance = new Derived(); // upcast: var baseReference = (IBase) derivedInstance; // downcast: var derivedReference = (IDerived) baseReference; } }
interface IBase; interface IDerived : IBase; class Derived : IDerived; class Sample { public Sample() { var derivedInstance = new Derived(); // implicit upcast: IBase baseReference = derivedInstance; // downcast: var derivedReference = (IDerived) baseReference; } }

Such initialization of baseReference will not compile if the derivedInstance variable changes its type so that it is no longer compatible with IBase.

Last modified: 25 July 2024