C# inherits the determination of IsAssignableFrom, IsSubclassOf

Little scum · Posted on 11/18/2019 11:45:09 AM

Sometimes we need to determine whether a class implements an interface, such as when using a reflection mechanism to find a specific type.

In simple terms, you can use the Type.IsAssignableFrom method:

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IsAssignableFrom indicates whether the BarClass type can be assigned to the IFoo interface, so the condition for it to return true is that BarClass directly or indirectly implements the IFoo interface. There is also a method in the Type type, IsSubclassOf, which isOnlyUsed to judge inheritance relationships of classes, such as

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Indicates that FooClass is inherited from BarClass.

Of course, IsAssignableFrom can also be used to determine inheritance.

So, for the following code:

interface I { /* ... */ }
class A : I { /* ... */ }
class B : A { /* ... */ }

The return values for IsSubclassOf and IsAssignableFrom are:

typeof(A).isAssignableFrom(typeof(I)); // false
typeof(A).isSubClassOf(typeof(I)); // false

typeof(I).isAssignableFrom(typeof(A)); // true
typeof(I).isAssignableFrom(typeof(B)); // true
typeof(B).isSubClassOf(typeof(I)); // false

typeof(A).isAssignableFrom(typeof(A)); // true
typeof(A).isSubClassof(typeof(A)); // false

typeof(A).isAssignableFrom(typeof(B)); // true
typeof(A).isSubClassof(typeof(B)); // false

typeof(B).isAssignableFrom(typeof(A)); // false
typeof(B).isSubClassof(typeof(A)); // true

Little scum · Posted on 3/19/2021 1:39:47 PM

Gets an object that inherits a generic base class

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[Source] C# inherits the determination of IsAssignableFrom, IsSubclassOf

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