I wrote a function in c# which initially returned a named tuple. But now, I only need one field of this tuple and I would like to keep the name because it helps me to understand my code.
private static (bool informationAboutTheExecution, bool field2thatIdontNeedAnymore) doSomething() {
// do something
return (true, false);
}
This function compile. But It's the following function that I want
private static (bool informationAboutTheExecution) doSomething() {
// do something
return (true);
}
the error messages:
Tuple must containt at least two elements
cannot implcitly convvert type 'bool' to '(informationAboutTheExecution,?)
Has somebody a solution to keep the name of the returned value?
You cannot, basically. You can return a ValueTuple<bool>, but that doesn't have names. You can't add [return:TupleElementNamesAttribute] manually, as the compiler explicitly does not let you (CS8138). You could just return bool. You can do the following, but it isn't any more helpful than just returning bool:
private static ValueTuple<bool> doSomething()
=> new ValueTuple<bool>(true);
Part of the problem is that ({some expression}) is already a valid expression before value-tuple syntax was introduced, which is why
private static ValueTuple<bool> doSomething()
=> (true);
is not allowed.
If you must name your return, you can do this:
private static void doSomething(out bool information) {
// do something
information = true;
}
then call it with
bool result;
doSomething(out result);
I just want to add another option, althought he out is the easiest workaround and Marc explained already why it's not possible. I would simply create a class for it:
public class ExecutionResult
{
public bool InformationAboutTheExecution { get; set; }
}
private static ExecutionResult DoSomething()
{
// do something
return new ExecutionResult{ InformationAboutTheExecution = true };
}
The class can be extended easily and you could also ensure that it's never null and can be created with factory methods like these for example:
public class SuccessfulExecution: ExecutionResult
{
public static ExecutionResult Create() => new ExecutionResult{ InformationAboutTheExecution = true };
}
public class FailedExecution : ExecutionResult
{
public static ExecutionResult Create() => new ExecutionResult { InformationAboutTheExecution = false };
}
Now you can write code like this:
private static ExecutionResult DoSomething()
{
// do something
return SuccessfulExecution.Create();
}
and in case of an error(for example) you can add a ErrorMesage property:
private static ExecutionResult DoSomething()
{
try
{
// do something
return SuccessfulExecution.Create();
}
catch(Exception ex)
{
// build your error-message here and log it also
return FailedExecution.Create(errorMessage);
}
}