C# problems with generic function and classes

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3.00/5 (1 vote)

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Hi.

To be very brief, I get the error saying "cannot convert from type T to int, or to double ......"
here is the code

public class Class1<t>
{
    public Func<t> getter;

    public Class1(Func<t> getter)
    {
        this.getter = getter;
    }
}

public class Class2
{
    public Class1<bool> boolData;
    public Class1<int> intData;
    public Class1<long> longData;
    public Class1<float> floatData;
    public Class1<double> doubleData;
    public Class1<string> stringData;

}

public class Main
{
    public Class2 data;

    public void TryMe<t>(Func<t> getter)
    {
        if(typeof(T) == typeof(int))
        {
            data.intData = new Class1<int>(getter);
            // ABOVE LINE

        }
        else if(typeof(T) == typeof(double))
        {
            data.intData = new Class1<double>(getter);
        }
        // and so on for bool, long, float and string
    }
}

[edit]Code block inserted to preserve formatting. "<" and ">" characters escaped to preserve meaning... - OriginalGriff[/edit]

Posted 23-Sep-10 6:20am

barbarini

Updated 23-Sep-10 6:44am

OriginalGriff

v2

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E.F. Nijboer · Answer 1 · 2010-09-23T07:19:00

Solution 1

When you apply copy-paste... be sure to update all relevant items. ;)

data.intData = new Class1<double>(getter);

You are putting a class1 double into the intData placeholder.

Posted 23-Sep-10 7:19am

E.F. Nijboer

Comments

barbarini 24-Sep-10 16:44pm

my mistake... the line shoud be:
data.doubleData = new Class1"<double>"(getter);
but still I get the same error.... ?????

E.F. Nijboer 25-Sep-10 13:34pm

Your way of using generics is a bit strange to be honestly. You are using a template type to store a template type parameter into a pre typed template typed property. So, instead of finding what is wrong here, it would be more interesting to implement it somewhat more effective. A template is used to store any type into the same placeholder instead of all kinds of placeholders of pre typed templates.

public class Class1
{
public Func<t> getter;

public Class1(Func<t> getter)
{
this.getter = getter;
}

public int getInt()
{
if(typeof(T) == typeof(int))
{
return getter;
} else
{
return 0;
}
}

You could fill this with more conversions and also implement automatic casting between types. There are also sophisticated methods to do that but for now this is a nice start.