Menu
Search

Forums

Forum Index

July 07, 2022
Gravatar of Alexandru ErmicioiPosted by Alexandru Ermicioi
in reply to 12345swordy		Reply
Alexandru Ermicioi
Gravatar of Alexandru Ermicioi
Posted in reply to 12345swordy


Reply
On Thursday, 7 July 2022 at 13:59:17 UTC, 12345swordy wrote:
> Side note: Does D really needs function overloading? You can achieve the same effect by using meta-programming.
>
> - Alex

Just wondering, how do you achieve it using meta-programming?
July 07, 2022
Gravatar of Nick TreleavenPosted by Nick Treleaven
in reply to Alexandru Ermicioi		Reply
Nick Treleaven
Gravatar of Nick Treleaven
Posted in reply to Alexandru Ermicioi


Reply

On Thursday, 7 July 2022 at 15:19:59 UTC, Alexandru Ermicioi wrote:

>

On Thursday, 7 July 2022 at 13:59:17 UTC, 12345swordy wrote:

>

Side note: Does D really needs function overloading? You can achieve the same effect by using meta-programming.

  • Alex

Just wondering, how do you achieve it using meta-programming?

For non-virtual functions, just use a template function:

auto f(T)(T v)
{
	static if (is(T : int))
		// insert code for f(int) overload
	else
		...
}

It doesn't work for virtual functions as they can't be templates.

July 07, 2022
Gravatar of Alexandru ErmicioiPosted by Alexandru Ermicioi
in reply to Nick Treleaven		Reply
Alexandru Ermicioi
Gravatar of Alexandru Ermicioi
Posted in reply to Nick Treleaven


Reply

On Thursday, 7 July 2022 at 15:51:08 UTC, Nick Treleaven wrote:

>

For non-virtual functions, just use a template function:

auto f(T)(T v)
{
	static if (is(T : int))
		// insert code for f(int) overload
	else
		...
}

This solution feels like a huge downgrade compared to existing functionality. Reminds me of php or javascript, plus you'd need to handle yourself error handling if arguments don't match.

July 07, 2022
Gravatar of Timon GehrPosted by Timon Gehr
in reply to Walter Bright		Reply
Timon Gehr
Gravatar of Timon Gehr
Posted in reply to Walter Bright


Reply
On 7/6/22 20:30, Walter Bright wrote:
> On 7/5/2022 4:19 PM, Timon Gehr wrote:
>> I.e., in terms of type checking, everything has already been figured out and works:
> 
> That example just hurts my brain :-/

Well, I don't recommend people use that specific pattern, but it makes a lot of sense that it works in this way.

`x=>x` type checks as a `T delegate(T)` for any `T`.

`(x){}` does not type check as a `T delegate(T)` for any `T`.

The delegate literal is polysemous, and when trying to determine matches, it's instantiated for each potential match. Therefore, if a function accepts a `T delegate(T)`, the lambda can decide with `static if` if there is a match or not, arbitrarily depending on `T`.

(Note that all instantiations have to type check, as D does not have SFINAE.)
July 08, 2022
Gravatar of 12345swordyPosted by 12345swordy
in reply to Nick Treleaven		Reply
12345swordy
Gravatar of 12345swordy
Posted in reply to Nick Treleaven


Reply

On Thursday, 7 July 2022 at 15:51:08 UTC, Nick Treleaven wrote:

>

On Thursday, 7 July 2022 at 15:19:59 UTC, Alexandru Ermicioi wrote:

>

On Thursday, 7 July 2022 at 13:59:17 UTC, 12345swordy wrote:

>

Side note: Does D really needs function overloading? You can achieve the same effect by using meta-programming.

  • Alex

Just wondering, how do you achieve it using meta-programming?

For non-virtual functions, just use a template function:

auto f(T)(T v)
{
	static if (is(T : int))
		// insert code for f(int) overload
	else
		...
}

It doesn't work for virtual functions as they can't be templates.

This can be solved by having a top type named "Any" to indicate that it can be any type for virtual functions.

-Alex

July 08, 2022
Gravatar of Paul BackusPosted by Paul Backus
in reply to 12345swordy		Reply
Paul Backus
Gravatar of Paul Backus
Posted in reply to 12345swordy


Reply

On Friday, 8 July 2022 at 13:35:12 UTC, 12345swordy wrote:

>

On Thursday, 7 July 2022 at 15:51:08 UTC, Nick Treleaven wrote:

>

For non-virtual functions, just use a template function:

auto f(T)(T v)
{
	static if (is(T : int))
		// insert code for f(int) overload
	else
		...
}

It doesn't work for virtual functions as they can't be templates.

This can be solved by having a top type named "Any" to indicate that it can be any type for virtual functions.

Actually, you can already do this with variadic functions and TypeInfo. Take a look at the third example:

https://dlang.org/spec/function.html#d_style_variadic_functions

July 08, 2022
Gravatar of 12345swordyPosted by 12345swordy
in reply to Paul Backus		Reply
12345swordy
Gravatar of 12345swordy
Posted in reply to Paul Backus


Reply

On Friday, 8 July 2022 at 14:11:08 UTC, Paul Backus wrote:

>

On Friday, 8 July 2022 at 13:35:12 UTC, 12345swordy wrote:

>

On Thursday, 7 July 2022 at 15:51:08 UTC, Nick Treleaven wrote:

>

For non-virtual functions, just use a template function:

auto f(T)(T v)
{
	static if (is(T : int))
		// insert code for f(int) overload
	else
		...
}

It doesn't work for virtual functions as they can't be templates.

This can be solved by having a top type named "Any" to indicate that it can be any type for virtual functions.

Actually, you can already do this with variadic functions and TypeInfo. Take a look at the third example:

https://dlang.org/spec/function.html#d_style_variadic_functions

"TypeInfo" isn't a Top type though, nor should it be treated as one.

« First   ‹ Prev
1 2 3 4 5 6
Next ›   Last »