CODEWITHSUNDEEP
c#reflectionmscorlib
rrrr-o
rrrr-o

Reputation: 2516

Why does GetName in System.Reflection.Assembly appear to throw a NotImplementedException when decompiled?

While debugging an issue I was digging in to mscorlib and specifically at GetName() in System.Reflection.Assembly.

Looking at the code for the method in dotPeek and also on reference source the code for GetName() seems to have nothing in it and throws a NotImplementedException:

#if FEATURE_CORECLR
    [System.Security.SecurityCritical] // auto-generated
#endif
    public virtual AssemblyName GetName()
    {
        return GetName(false);
    }

#if FEATURE_CORECLR
    [System.Security.SecurityCritical] // auto-generated
#endif
    public virtual AssemblyName GetName(bool copiedName)
    {
        throw new NotImplementedException();
    }

Can anyone explain why this appears to throw an exception, but using a line of code such as typeof(object).GetTypeInfo().Assembly.GetName().Version.ToString() returns the correct version of the DLL?

Upvotes: 0

Views: 274

Answers (1)

Lasse V. Karlsen
Lasse V. Karlsen

Reputation: 391406

That's because Assembly is a base class, the actual object you get back at runtime (in this particular setting) is a RuntimeAssembly which does implement that method.

Depending on how you obtain the Assembly object, there are different actual types at play, be it for actual runtime code or reflection-only spelunking or whatnot.

But Assembly is a base class.

I can say this unequivocally because the Assembly class is abstract, as evident from the reference source:

public abstract class Assembly : _Assembly, IEvidenceFactory, ICustomAttributeProvider, ISerializable

And it's also documented:

[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)]
[System.Runtime.InteropServices.ComVisible(true)]
public abstract class Assembly : System.Reflection.ICustomAttributeProvider, System.Runtime.InteropServices._Assembly, System.Runtime.Serialization.ISerializable, System.Security.IEvidenceFactory

Therefore, any instance of an object that fits an Assembly variable has to be a derived class.

Upvotes: 3

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