Return unsafe pointer to type parameter

Question

I am trying to define a property that returns a pointer to a generic type argument like so:

public class MemWrapper where T: struct
{
    readonly I         


        

Answer 1

Generics and pointers don't work well together, but this is actually a perfect fit for "ref return":

public class MemWrapper<T> where T : struct
{
    readonly IntPtr pointerToUnmanagedHeapMem;

    // ... do some memory management also ...

    public unsafe ref T Ptr
    {
        get { return ref Unsafe.AsRef<T>(pointerToUnmanagedHeapMem.ToPointer()); }
    }
}

Alternative Ptr syntax:

public unsafe ref T Ptr => ref Unsafe.AsRef<T>(pointerToUnmanagedHeapMem.ToPointer());

Note that this requires recent versions of Unsafe; here I'm using:

<PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.4.0" />

Note that you now don't need unsafe in the consuming code - just the one property that touches pointerToUnmanagedHeapMem.

Consuming code:

var wrapper = ... // some MemWrapper<T>
ref Foo foo = ref wrapper.Ptr;
Console.WriteLine(foo.SomeProperty); // not foo->SomeProperty
SomeInnerMethod(ref foo); // pass down to other ref Foo methods

no unmanaged pointers; the code is now perfectly "safe" outside of .Ptr.

Note: if you need to talk about multiple consecutive items: Span<T>/Memory<T> are your friends.