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c#linqgenericscasting
stackMeUp
stackMeUp

Reputation: 552

Convert all T values using LINQ and assign them to an array of different type

I wish to be able to modify some parameter value of generic type T, and I am trying to do this with LINQ, but I cannot figure it out.
Here is what I have: 

public static T ConvertParam(T param)
{    
    T val = param.Select(i => { i = (T)ModifyValue(Convert.ToDouble(i)); });

    return val;
}

public static UInt64 ModifyValue(double value)
{
    UInt64 result = (UInt64)(value) * 3 + 1;

    return result;
}

In this case the problem resides in the value returned by "ModifyValue()" that needs to be cast to whatever T param contains, but I am not sure how to do that. T can be an int, uint, int[], uint[], etc.
Handling the arrays is also tricky.

I have also tried with a normal for loop as here below: 

public static T ConvertParam(T param)
{
    List<UInt64> output = new List<UInt64>();

    foreach (var v in param)
    {
        output.Add(ModifyValue(Convert.ToDouble(v));
    }

    return output.ToArray();
}

The problem here again is that the returned value may or may not be an array. It should just return the modified version of T param.

EDIT

Note that ModifyValue() is just a dummy example. "param" MUST be generic!

EDIT 2

Maybe I could do something around these lines (not sure how to though): 

public static T ConvertParam(T param)
{
    T ret = param.ToList().ConvertAll(i => i = new T() { ModifyValue(Convert.ToDouble(i)) });

    return ret;
}

Upvotes: 0

Views: 121

Answers (1)

Mike Hanson
Mike Hanson

Reputation: 306

It doesn't look to me like that would actually compile.

I think you have two vital things missing first as Pavel suggested in his comment you are returning T from ConvertParam and it takes and argument of T, but you haven't declared T.

Secondly, you are using LINQ against a generic type, but there is nothinh that allows the compiler to know that param is queryable by LINQ. I think you need to change your code to something like this


public static IEnumerable<T> ConvertParam<T>(IEnumerable<T> param)
{
    // This seems redundant
    // List<UInt64> output = new List<UInt64>(); 

    var val = param.Select(i => (T)ModifyValue(Convert.ToDouble(i)));

    return val;
}

public static UInt64 ModifyValue(double value)
{
    UInt64 result = (UInt64)(value) * 3 + 1;

    return result;
}

EDIT: As others have said I'm not sure your code makes sense from a use case point of view.

Upvotes: 1

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