Question

Good evening,

I was wondering if I could do something like:

while(true)
{
   MyEnum currentValue = GetMyEnumValueFromDB();
   if(currentValue == MyEnum.BreakIfYouGetThis)
      break;
   else if(currentValue == MyEnum.AlsoBreakIfYouGetThis)
      break;
   else
      //Do some computing
}

But instead of having a while(true) loop, I’d want to encapsulate the conditional logic in a Func and execute it like this:

while(new Func<bool>(/* what goes here? */))
{
   //Do some computing
}

In my case at least, it would look much cleaner, but i’m not sure how to do it (kinda new at Func/Action..).

EDIT hope this clarifies:
It could also be done like this:

while(GetMyEnumValueFromDB() != MyEnum.BreakIfYouGetThis && 
      GetMyEnumValueFromDB() != MyEnum.AlsoBreakIfYouGetThis)
{
   //Do some computing
}

But that’s 2 call to the database…

Thanks =)

Answer 1

Well you could have:

Func<bool> condition = ...;

while (condition())
{
}

Is that what you’re thinking of? It’s not really clear…

EDIT: In the example you’ve given, I’d use something like:

private static readonly MyEnum[] BreakEnumValues = { 
    MyEnum.BreakIfYouGetThis,
    MyEnum.AlsoBreakIfYouGetThis
};

...

while (!BreakEnumValues.Contains(GetMyEnumValueFromDB()))
{
    ...
}

Or:

private static bool ShouldBreak(MyEnum enumFromDatabase)
{
    return enumFromDatabase == MyEnum.BreakIfYouGetThis ||
           enumFromDatabase == MyEnum.AlsoBreakIfYouGetThis;
}

...

while (!ShouldBreak(GetMyEnumValueFromDB))
{
    ...
}

EDIT: To counter KeithS’s answer, this is entirely valid:

while (new Func<bool>(() => {
    Console.WriteLine("Evaluating...");
    return true;
})()) {
    Console.WriteLine("In loop");
    count++;
    if (count == 5)
    {
        break;
    }
}

It’s horrible, but it’s valid. (It can be made slightly less horrid by explicitly calling Invoke, but it’s still not nice.)