For example:
public class Stereo {
public Speaker? LeftSpeaker;
public int? Volume;
}
The int? works fine, but I'm unable to make Speaker nullable. This is turning out to be surprisingly hard to Google, I thought this would be simple ...
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4 Answers
Why would you want that? Non-value types (i.e. reference types) can already be set and compared to null.
Adding a Nullable<T> wrapper over reference-type objects would create two layers of nullability; pointless complexity, hence it is not allowed.
2 Comments
Joel Etherton
Half tempted to retag this question
duh.
user500038
Well this could be why Googling "make reference types nullable" wasn't turning up anything. Thanks!
It is simple. "non-value" types are actually called references types in .NET and are automatically nullable. Just change your code thusly:
public class Stereo {
public Speaker LeftSpeaker; // ? removed for ref type
public int? Volume;
}
Comments
Wild swag:
public class Stereo {
public Speaker LeftSpeaker;
public int? Volume;
public Stereo() {
LeftSpeaker = null; // Mission accomplished.
}
}
4 Comments
Joel Etherton
@Noldorin: woops. missed some
() didn't I?
Noldorin
Yeah, just though I'd fix it for you, since it was an obvious typo. :)
Joel Etherton
@Noldorin: No sweat. I've been mass-producing properties in dummy classes for the last couple of days, so my brain is just glossy :)
Noldorin
Yep, that would a cause! Easy mistake to make anyway, outside of a code editor.
A lot of fish already here - but if you want to learn how to fish, I suggest having a look into Jon Skeet's book C# in Depth. Chapters 4.1 to 4.5 are dealing with all facets of the "concept of nullity" in C#.
