• Kyle Ingraham (17/17) Sep 10 2022 Is there a way to write a delegate type as being specific for
• Adam D Ruppe (9/11) Sep 10 2022 That's not a type per se, but you can assign wrapper at the
• Kyle Ingraham (14/26) Sep 10 2022 My problem is that I would like to store a reference to that
• Adam D Ruppe (9/15) Sep 10 2022 Some kind of wrapper might not only be your best option, it might
• Kyle Ingraham (7/23) Sep 12 2022 Thanks for the wrapper suggestion Adam. I tried that out and got

Kyle Ingraham <kyle kyleingraham.com> writes:

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:

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

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

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

That type would not work for this function though:

```d
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?

Adam D Ruppe <destructionator gmail.com> writes:

On Saturday, 10 September 2022 at 23:37:30 UTC, Kyle Ingraham 
wrote:
 How can I write a type that is strict for the first two 
 parameters but tolerant of any other parameter following those?

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.

Kyle Ingraham <kyle kyleingraham.com> writes:

On Sunday, 11 September 2022 at 00:04:55 UTC, Adam D Ruppe wrote:
 On Saturday, 10 September 2022 at 23:37:30 UTC, Kyle Ingraham 
 wrote:
 How can I write a type that is strict for the first two 
 parameters but tolerant of any other parameter following those?

 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.

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

```d
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.

Adam D Ruppe <destructionator gmail.com> writes:

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

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'm mucking about with a custom router for vibe-d and trying to 
 setup the ability for handlers to have different parameter 
 signatures.

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)

Kyle Ingraham <kyle kyleingraham.com> writes:

On Sunday, 11 September 2022 at 00:56:39 UTC, Adam D Ruppe wrote:
 On Sunday, 11 September 2022 at 00:32:18 UTC, Kyle Ingraham 
 wrote:
 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

 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'm mucking about with a custom router for vibe-d and trying 
 to setup the ability for handlers to have different parameter 
 signatures.

 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)

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.