Is it possible to put only one option on a ternary expression?

Question

I am just curious if this is possible or is there a way for this to become a valid syntax for C#:

expression == value ? /*do nothing here, or put some empty block like { ; } */ : SomeClass.SomeMethod();

Edit: For an in-depth discussion and more information, I thought this block would work (if the dictionary key tested does not exist, it adds the dictionary. else, it would skip):

(!packageDict.ContainsKey(desc)) ? packageDict.Add(desc, subtotal) : /*does nothing*/;

Answer 1

By looking at your code snippet, it simply makes no sense to use a ternary operation here.

All you can do is:

if (!packageDict.ContainsKey(desc))
    packageDict.Add(desc, subtotal)

Answer 2

No, and that makes sense. What would expression be in your no-operation action? null? The same as it was? How should the compiler know that?

This for example will leave the variable unset. What is expression here?

var expression == value ? : SomeClass.SomeMethod();

Just make explicit what you expect, so either this:

expression == value ? null : SomeClass.SomeMethod();

expression == value ? default(Expression) : SomeClass.SomeMethod();

Or this to keep the variable the same when value is true:

expression == value ? expression : SomeClass.SomeMethod();

if (!value) expression = SomeClass.SomeMethod();

Answer 3

You should use an IF statement (it is also the most readable option).

An alternative is to use default for your type (e.g. null for reference types or default(value_type) for value types. E.g:

expression == value ? (int?) null : SomeClass.SomeMethod();