Is there a way to write a delegate type as being specific for some parameters and tolerant of anything for others? For example, I can specify this type:

alias MyDelegateType = void delegate(string name, int age);

It would be compatible with a pointer to this function converted to a delegate:

void someFunc(string name, int age) { // }

That type would not work for this function though:

void anotherFunc(string name, int age, string location) { // }

How can I write a type that is strict for the first two parameters but tolerant of any other parameter following those?

On Saturday, 10 September 2022 at 23:37:30 UTC, Kyle Ingraham wrote:

That's not a type per se, but you can assign wrapper at the assignment thing.

Like

your_delegate = (a,b) => func_with_three_args(a, b, "some default");

that kind of thing. if you have a delegate in an object, you can use a property setter to accept more things and wrap it like that.

On Sunday, 11 September 2022 at 00:04:55 UTC, Adam D Ruppe wrote:

My problem is that I would like to store a reference to that delegate in a struct for later use:

struct MyStruct
{
    MyDelegate myDelegate;
}

I can't use default parameters because I want to be able to call the delegate with arguments extracted from a URL path at runtime. I'm mucking about with a custom router for vibe-d and trying to setup the ability for handlers to have different parameter signatures.

On Sunday, 11 September 2022 at 00:32:18 UTC, Kyle Ingraham wrote:

Some kind of wrapper might not only be your best option, it might be your only option.

Your delegate would be like string callWith(string[][string] webArgs) and you can generate a wrapper to convert arguments and call the original function.

I'd be surprised if vibe doesn't already have this built in, my web frameworks have since before vibe was born. (my implementation btw does the wrapper thing like described above)

On Sunday, 11 September 2022 at 00:56:39 UTC, Adam D Ruppe wrote:

Thanks for the wrapper suggestion Adam. I tried that out and got the functionality that I wanted. I wrap the handler in a delegate that has the signature I need.

vibe-d does have a way to achieve something similar but I'm working on a router that does a bit more path validation before calling a handler.