C#•9mo ago

Delegate function with params

Hello, is it possible to somehow have "named" parameters in the delegate function? Right now I have:

public delegate bool ValidatorF<T>(params T[] args);

// Usage
public static class IntValidator
{
    public static ValidatorF<int> IsExact = args => args[0] == args[1];
}

public delegate bool ValidatorF<T>(params T[] args);

// Usage
public static class IntValidator
{
    public static ValidatorF<int> IsExact = args => args[0] == args[1];
}

But that way you have to remember that the first argument is the actual number and the second argument is the expected value for example (In this case it doesn't matter, but let's say we have 3+ args..) My question is: Is it possible to have the usage like this somehow? Or using some other approach?

 public static ValidatorF<int> IsExact = (val, expected)=> val == expected;

 public static ValidatorF<int> IsExact = (val, expected)=> val == expected;

14 Replies

Pobiega•9mo ago

Change the delegate to not take params T[] args?

popcornOP•9mo ago

I need to take the function from user and I only know that the return type is bool and that any number of params is T type. But I don't know how many params

Pobiega•9mo ago

okay, then the answer is no

popcornOP•9mo ago

Ah okay. Then this must be enough 😄

Pobiega•9mo ago

you can ofc do somethng like

public delegate bool ValidatorF<T>(params T[] args);

// Usage
public static class IntValidator
{
    public static ValidatorF<int> IsExact = args => IsExactImpl(args[0], args[1]);

    private static bool IsExactImpl(int actual, int expected)
    {
        return actual == expected;
    }
}

public delegate bool ValidatorF<T>(params T[] args);

// Usage
public static class IntValidator
{
    public static ValidatorF<int> IsExact = args => IsExactImpl(args[0], args[1]);

    private static bool IsExactImpl(int actual, int expected)
    {
        return actual == expected;
    }
}

, but that doesnt help the external usage

popcornOP•9mo ago

Yeah, I'm thinking about just supporting limited number of parameters, just as it is with the generic Func<> where you can only have up to 16 params

Pobiega•9mo ago

sure

popcornOP•9mo ago

Like this:

public static Func<int, int, bool> IsExact2 = (val, expected) => val == expected;

public static Func<int, int, int, bool> IsInBounds = (val, upperBound, lowerBound) => lowerBound >= val && val <= upperBound;

public static Func<int, int, bool> IsExact2 = (val, expected) => val == expected;

public static Func<int, int, int, bool> IsInBounds = (val, upperBound, lowerBound) => lowerBound >= val && val <= upperBound;

Pobiega•9mo ago

mhm thats much better, if you ask me

popcornOP•9mo ago

But then I would have to overload x number of times the generic method. So I would have:

public OptionBuilder<T> ValidationFunc(Func<T, T, bool> validator) { // Save the func to variable }

public OptionBuilder<T> ValidationFunc(Func<T, T, T, bool> validator) { // Save the func to variable }

public OptionBuilder<T> ValidationFunc(Func<T, T, bool> validator) { // Save the func to variable }

public OptionBuilder<T> ValidationFunc(Func<T, T, T, bool> validator) { // Save the func to variable }

And I then I would have to somehow decide which function was actually provided and call that So I would have X number of variables with these functions I guess?

Pobiega•9mo ago

yeah btw Func<T, bool> is the same as Predicate<T>

popcornOP•9mo ago

Cool, didn't know about that one. Thanks I guess sacrificing the complexity of the "library" is better for the comfort of user defined functions.

Pobiega•9mo ago

yes, absolutely thats half the point of libraries 🙂

popcornOP•9mo ago

Okay, thank you for your opinion ❤️

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Delegate function with params