Task.Run with Input Parameters and Output

Question

This works great:

private void MainMethod()
{
    Task<bool> taskItemFound = new Task<bool>(ItemFound);
}

private bool ItemFound()
{
    //Do Work
    return true;
}

This works but is UGLY and I can't pass more than one parameter:

private void MainMethod()
{
    var startNew = Task<bool>.Factory.StartNew(TempMethod, "cow");
}

private bool TempMethod(object o)
{
    return ("holy " + o == "holy cow");
}

I'm looking for a solution that will give me a Task<bool> from an existing method with more than one input parameter and that returns a bool. Ideally, it would look like this:

Task<bool> taskItemFound = new Task<bool>(ItemFound(param1, param2, param3));

Gregor Mohorko · Accepted Answer · 2018-03-31 11:58:48Z

6

You can do:

bool result = await Task.Run(() => ItemFound(param1, param2, param3) );

Or if you really want it as Task<bool>:

Task<bool> t = new Task<bool>(() => ItemFound(param1, param2, param3) );

answered Mar 31, 2018 at 11:58

Gregor Mohorko

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6 Comments

Henk Holterman Over a year ago

Yes, but worth noticing that param1, param2 etc are now captured (closed over). They are treated very differently from the original object o

Gregor Mohorko Over a year ago

Can that cause any side effects? How are they treated differently?

Henk Holterman Over a year ago

Yes, they are shared and their scope and lifetime are hard to control or even gauge.

LorneCash Over a year ago

But I'm also curious now... @GregaMohorko How are they different, and what side effects might i look out for?

BineG Over a year ago

@GregorMohorko Their values can change by the time they are used in the lambda function. Not ideal...

|

Just Shadow · Accepted Answer · 2020-01-18 10:46:14Z

Actually, a more clear way would be passing the parameters inside an object. Below you can find solutions to easily achieve that.

Solution 1 (long but clear): Pass an object which holds the parameters

Just create a class which holds the parameters:

class CustomParams
{
   public int Param1 { get; set; }
   public int Param2 { get; set; }
   public int Param3 { get; set; }
}

Then in the method just to cast the object to the class

private bool TempMethod(object arguments)
{
    var args = arguments as CustomParams;
    // Do anything with args.Param1
    // Do anything with args.Param2
    // Do anything with args.Param3
    // Return anything
    return ("holy " + args.Param1 == "holy cow");
}

And to call, use this:

Task<bool> taskItemFound = new Task<bool>(TempMethod, new CustomParams {
    Param1 = 3,
    Param2 = 5,
    Param3 = 2
});

Solution 2 (hacky but shorter): Use Tuples as parameters

This can be used in case you don't want to create a class

Modify the method to cast the object to tuple:

private bool TempMethod(object arguments)
{
    var args = arguments as Tuple<int,int,int>;
    // Do anything with args.Item1
    // Do anything with args.Item2
    // Do anything with args.Item3
    // Return anything
    return ("holy " + args.Item1 == "holy cow");
}

Then use:

Task<bool> taskItemFound = new Task<bool>(ItemFound, new Tuple<int, int>(3,5,7));

Solution 3 (super-hacky, and short): Use dynamic objects

Modify the method to accept dynamic instead of object:

private bool TempMethod(dynamic arguments)
{
    // Do anything with args.Param1
    // Do anything with args.Param2
    // Do anything with args.Param3
    // Return anything
    return ("holy " + arguments.Param1 == "holy cow");
}

And then call using this:

Task<bool> taskItemFound = new Task<bool>(TempMethod, new {Param1 = 3, Param2 = 44, Param3 = 564 });

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Task.Run with Input Parameters and Output

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6 Comments

Solution 1 (long but clear): Pass an object which holds the parameters

Solution 2 (hacky but shorter): Use Tuples as parameters

Solution 3 (super-hacky, and short): Use dynamic objects

Comments

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Collectives™ on Stack Overflow

2 Answers 2

6 Comments

Solution 1 (long but clear): Pass an object which holds the parameters

Solution 2 (hacky but shorter): Use Tuples as parameters

Solution 3 (super-hacky, and short): Use dynamic objects

Comments

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