CODEWITHSUNDEEP
c#genericsdelegatesoverloading
tdbeckett
tdbeckett

Reputation: 708

Providing an specific overloaded method to a method that accepts Func as parameter

I am using a delegate parameter in a method. I would like to provide an overloaded method that matches the delegate signature. The class looks like this:

public class Test<DataType> : IDisposable
{
        private readonly Func<string, DataType> ParseMethod;

        public Test(Func<string, DataType> parseMethod)
        {
           ParseMethod = parseMethod;
        }

        public DataType GetDataValue(int recordId)
        {
          // get the record
          return ParseMethod(record.value);
        }
}

Then I tried to use it:

using (var broker = new Test<DateTime>(DateTime.Parse))
{
   var data = Test.GetDataValue(1);
   // Do work on data.
}

Now DateTime.Parse has a signature that matches the Func; However, because it's overloaded, the compiler can't resolve which method to use; seems obvious in hind site!

I then tried:

using (var broker = new Test<DateTime>((value => DateTime.Parse(value))))
{
   var data = Test.GetDataValue(1);
   // Do work on data.
}

Is there a way to specify the correct method with out writing a custom method that simply calls the DateTime.Parse?

Upvotes: 0

Views: 81

Answers (1)

DLCross
DLCross

Reputation: 704

I think your first example is almost correct. It's hard to tell because there's some missing code, but I believe the problem is that the compiler can't tell that record.value is a string--maybe it's an object? If so, casting it to a string inside GetDataValue should make the compiler happy.

Here's the similar example I tried, which compiled and ran fine:

    class Test<X>
    {
        private readonly Func<string, X> ParseMethod;

        public Test(Func<string, X> parseMethod)
        {
            this.ParseMethod = parseMethod;
        }

        public X GetDataValue(int id)
        {
            string idstring = "3-mar-2010";
            return this.ParseMethod(idstring);
        }
    }

    [TestMethod]
    public void TestParse()
    {
        var parser = new Test<DateTime>(DateTime.Parse);
        DateTime dt = parser.GetDataValue(1);
        Assert.AreEqual(new DateTime(day: 3, month: 3, year: 2010), dt);
    }

Upvotes: 1

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