Question

I’m teaching myself C#, so forgive me if this seems slightly obvious.

I’m trying to write a generic function that I can pass an array of structs into and then use one of the attributes of the struct. I have no idea how to declare a generic datatype in a function in a way that I can refer to attributes in the way needed.

Maybe what I’m asking can be better communicated in code – this is a non-working function to illustrate what I’m trying to do, how it strikes me as logical that it should work without actually knowing how to write it:

public static int AFunctionIsThis<DataType, int DataType.Value>(DataType passedrecord)
{
    temp = passedrecord.Value * 2 + 1;

    return temp;
}

And I want to be able to call it normally while specifying the attribute of the struct to be passed.

int NewVariable = AFunctionIsThis<ThisIsAStruct, ThisIsAStruct.AnIntAttribute>(ThisIsADeclaredStruct);

Thankyou very much,

Hanii Puppy.

Answer 1

(To start with, note that the word “attribute” has a different meaning in .NET from the OOP sense.)

Use a Converter<T,int> and Action<T,int> delegate to get and set the member, respectively.

e.g.

public static int AFunctionIsThis<DataType>(DataType passedrecord, Converter<DataType,int> getter)
{
    temp = getter(passedrecord) * 2 + 1;

    return temp;
}

and then call it

AFunctionIsThis(ThisIsADeclaredStruct, x => x.AnIntProperty);

If you also need to set the value, you can use

AFunctionIsThis(ThisIsADeclaredStruct, x => x.AnIntProperty, (x, v) => { x.AnIntProperty = v; });

or do some magic with Expression<Converter<T>> to yank out the member reference and create a matching setter.