Using ternary operator: "only assignment, call, increment..."

Question

I have action dictionary defined as:

var actions = new Dictionary<string, Action<string, string>>();

I put there actions like:

actions.Add("default", (value, key) => result.Compare(value, properties[key], Comparers.SomeComparer, key));
...

I'm using this code to run it:

if (actions.ContainsKey(pair.Key))
{
    actions[pair.Key](pair.Value, pair.Key);
}
else
{
    actions[""](pair.Value, pair.Key);
}

It works just fine, but I wanted to use '?' notation to make it shorter:

actions.ContainsKey(pair.Key) ? actions[pair.Key](pair.Value, pair.Key) : actions[""](pair.Value, pair.Key);

This code shows me error:

Error 1 Only assignment, call, increment, decrement, and new object expressions can be used as a statement

actions[pair.Key](pair.Value, pair.Key) isn't it a call? Am I missing something? Is it possible to use '?' notation with action dictionaries? I was trying to find something about that but it's hard to find anything about '?' operator and this error because '?' is ignored by google.

Answer 1

Try this instead:

actions[actions.ContainsKey(pair.Key) ? pair.key : ""](pair.Value, pair.Key);

This will fix your issue.

Answer 2

The ?: Conditional operator is defined as:

The conditional operator (?:) returns one of two values depending on the value of a Boolean expression

Your actions don't return a value, so what is the return value of ?: meant to be?