CODEWITHSUNDEEP
c#generics
John Doe
John Doe

Reputation: 3233

Trying to learn how to write methods that use generic type

I am trying to teach myself to leverage generic types when creating methods when possible. Is it possible to combine these 2 methods into one method that uses a generic type?

private Decimal? NullDec(string val)
{
    return String.IsNullOrEmpty(val) ? (Decimal?)null : Convert.ToDecimal(val);
}

private Int32? NullInt(string val)
{
    return String.IsNullOrEmpty(val) ? (Int32?)null : Convert.ToInt32(val);
}

Upvotes: 3

Views: 78

Answers (2)

Vlad
Vlad

Reputation: 221

I wrote some code for you.

Try to this one

public class NullTest
{
    public T Null<T>(string val, Func<string, T> func)
    {
        return func(val);
    }
}

public class TestConvert
{
    public int? ConvertToInt32Null(string val)
    {
        if (string.IsNullOrWhiteSpace(val))
            return null;
        return Convert.ToInt32(val);
    }

    public decimal? ConvertToDecimalNull(string val)
    {
        if (string.IsNullOrWhiteSpace(val))
            return null;
        return Convert.ToDecimal(val);
    }
}

class Program
{
    static void Main(string[] args)
    {
        var test = new NullTest();
        var converter = new TestConvert();

        int? t1 = test.Null("2", converter.ConvertToInt32Null);
        decimal? t2 = test.Null("", converter.ConvertToDecimalNull);
    }

}

Upvotes: 0

AGB
AGB

Reputation: 2226

It is possible to implement something like your methods with Convert.ChangeType(), but I am not sure it's advisable:

using System;

namespace Example
{
    internal class Program
    {
        public static void Main(string[] args)
        {
            var @int = Foo<int>("3");
            var @double = Foo<double>("3.14");
            var dateTime = Foo<DateTime>("01/02/2016");
            var @decimal = Foo<decimal>("3.1");

            Console.WriteLine($"{@int} is a {@int.GetType()}");
            Console.WriteLine($"{@double} is a {@double.GetType()}");
            Console.WriteLine($"{dateTime} is a {dateTime.GetType()}");
            Console.WriteLine($"{@decimal} is a {@decimal.GetType()}");

            Console.ReadLine();
        }

        public static T? Foo<T>(string val) where T : struct, IConvertible
        {
            return string.IsNullOrEmpty(val) ? null : Convert.ChangeType(val, typeof(T)) as T?;
        }
    }
}

Upvotes: 2

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