So I was told recently that how I was using my .ContinueWith for Tasks was not the proper way to use them. I have yet to find evidence of this on the internet so I will ask you guys and see what the answer is. Here is an example of how I use .ContinueWith:
public Task DoSomething()
{
return Task.Factory.StartNew(() =>
{
Console.WriteLine("Step 1");
})
.ContinueWith((prevTask) =>
{
Console.WriteLine("Step 2");
})
.ContinueWith((prevTask) =>
{
Console.WriteLine("Step 3");
});
}
Now I know this is a simple example and it will run very fast, but just assume each task does some longer operation. So, what I was told is that in the .ContinueWith, you need to say prevTask.Wait(); otherwise you could do work before the previous task finishes. Is that even possible? I assumed my second & third task would only run once their previous task finishes.
What I was told how to write the code:
public Task DoSomething()
{
return Task.Factory.StartNew(() =>
{
Console.WriteLine("Step 1");
})
.ContinueWith((prevTask) =>
{
prevTask.Wait();
Console.WriteLine("Step 2");
})
.ContinueWith((prevTask) =>
{
prevTask.Wait();
Console.WriteLine("Step 3");
});
}
You are using it correctly.
Source: Task.ContinueWith Method (Action as MSDN)
Having to call
prevTask.Wait()
in everyTask.ContinueWith
invocation seems like a weird way to repeat unnecessary logic - i.e. doing something to be "super duper sure" because you actually don't understand what a certain bit of code does. Like checking for a null just to throw anArgumentNullException
where it would've been thrown anyway.So, no, whoever told you that is wrong and probably doesn't understand why
Task.ContinueWith
exists.