C# Check which Parameters are set in an Named-Method

Question

I hope someone can help me or give me an information if that is even possible...

I want to check in an Named-Method which parameters are really set and passed to it. It would be possible to make an Dictionary and pass the parameter by an KeyValue-Pair to the Method, but is there an other solution?

Can i check the current method in the stack-trace and collect the current set argmuents of that method or something?

For better understanding, i created an example to visualize the issue:

class Program
{
    static void Main(string[] args)
    {
        TestClass newC = new TestClass("Init", 10);
        newC.ToString();    //{varStr: "Init"; varInt: 10}

        newC.update(vStr: "ok");

        newC.ToString();    //{varStr: "ok"; varInt: 0}     
                            // !!! but should have {varStr: "ok"; varInt: 10} !!!
        Console.WriteLine("<-- press any key to exit -->");
        Console.ReadKey();
    }
}

class TestClass
{
    string varStr;
    int varInt;

    public TestClass(string vStr, int vInt)
    {
        varStr = vStr;
        varInt = vInt;
    }

    public void update(string vStr = default, int vInt = default)
    {
        //here check it if vStr-Param was set and set varStr only if it was passed to it!
        //TODO
        varStr = vStr;
        //here check it if vInt-Param was set and set varInt only if it was passed to it!
        //TODO
        varInt = vInt;
    }

    public override string ToString()
    {
        Console.WriteLine($"TestClass: varStr: {varStr}; varInt: {varInt};");
        return null;
    }
}

Is there any way to achieve this, like the way i think?

EDIT:

Use default value and check it!

The default value can also be set over this Method! So an solution with checking the default value and only if that is equal than we set the value, is no option for us.

We have also an "custom-class" which we give over that method and it could also be nullable.

Use Overload methods!

The Problem is that this class has not 2 variables, it has over 15 and it would be an big overhead to write each overload method.

SOLUTION:

I found a Solution without declare default values... so every Value is able to be set!

    class TestClass
{
    string varStr;
    int varInt;
    TestClass1 varCustomClass;

    public TestClass(string vStr, int vInt, TestClass1 vCustomClass)
    {
        varStr = vStr;
        varInt = vInt;
        varCustomClass = vCustomClass;
    }

    public void update(Opt<int> varInt = default(Opt<int>),
                       Opt<string> varStr = default(Opt<string>),
                       Opt<TestClass1> varCustomClass = default(Opt<TestClass1>))
    {
        if (varStr.HasValue)
        {
            this.varStr = varStr.Value;
        }
        if (varInt.HasValue)
        {
            this.varInt = varInt.Value;
        }
        if (varCustomClass.HasValue)
        {
            this.varCustomClass = varCustomClass.Value;
        }
    }

    public override string ToString()
    {
        Console.WriteLine($"TestClass3: varStr: {varStr}; varInt: {varInt}; varCustomClass: {varCustomClass};");
        return null;
    }
}

public struct Opt<T>
{
    public Opt(T value)
    {
        _value = value;
        _hasValue = true;
    }

    public static explicit operator T(Opt<T> optional)
    {
        return optional._value;
    }

    public static implicit operator Opt<T>(T value)
    {
        return new Opt<T>(value);
    }

    T _value;
    public T Value
    {
        get { return _value; }
    }

    bool _hasValue;
    public bool HasValue
    {
        get { return _hasValue; }
    }
}

`if (vStr != default(string))`. Beware that the default of `string` (and any other reference type) is `null`, but the default of `int` (and any other value type) is an actual value. I.E `default(int) == 0` is true — MindSwipe, Nov 13 '20 at 08:20
just check if your variable has the default-value and if not assign the new value. — MakePeaceGreatAgain, Nov 13 '20 at 08:20
But we have the issue that we also use "null" for an String and it is possible that also the Integer-Variable can get any value ... also the value 0. — Brunhack, Nov 13 '20 at 08:23

score 1 · Answer 1 · answered Nov 13 '20 at 08:20

Might your string also be null? If not, you can check if it's null. For your int, you can use a nullable value type:

public void update(string vStr = null, int? vInt = null)
    {
        if(vStr != null)
        {
             varStr = vStr;
        }
        if(vInt != null)
        {
            varInt = vInt.Value;
        }
    }

If you have only a few parameters and they all have different types, overloaded methods are also a good solution:

public void update(string vStr)
 {
 varStr = vStr;
 }

public void update(int vInt)
 {
 varInt = vInt;
 }

public void update(string vStr, int vInt)
 {
 update(vStr);
 update(vInt);
 }

C# Check which Parameters are set in an Named-Method

1 Answers1