• IchorDev (22/22) Jul 20 Why does Phobos not provide a method to easily deconstruct
• Nick Treleaven (7/15) Jul 20 Instead of the `tie` assignment, you can just do:
• IchorDev (11/16) Jul 20 And here I was trying to use comma expressions for this like a
• Nick Treleaven (4/16) Jul 21 I think The lvalue sequence docs in template.dd were only updated

IchorDev <zxinsworld gmail.com> writes:

Why does Phobos not provide a method to easily deconstruct 
tuples? Here's a trivial implementation:
```d
//Similar to C++'s `std::tie`. Can anyone tell me why it's called 
`tie`?
void tie(T...)(typeof(T) src){
	static foreach(ind, i; src){
		T[ind] = i;
	}
}

//Usage example:
import std.stdio, std.typecons;

auto tupRetFn() => tuple(47, "test!");

void main(){
	string x = "discarded";
	int y;
	tie!(y, x) = tupRetFn().expand;
	writeln(x,", ",y);
}
```
Not having this is like if Phobos didn't have `AliasSeq`. Yes you 
can make your own, but it's wasteful boilerplate.

Nick Treleaven <nick geany.org> writes:

On Saturday, 20 July 2024 at 14:02:21 UTC, IchorDev wrote:
 Why does Phobos not provide a method to easily deconstruct 
 tuples? Here's a trivial implementation:

...
 	tie!(y, x) = tupRetFn().expand;
 	writeln(x,", ",y);
 }
 ```
 Not having this is like if Phobos didn't have `AliasSeq`. Yes 
 you can make your own, but it's wasteful boilerplate.

Instead of the `tie` assignment, you can just do:
```d
	import std.meta;
	AliasSeq!(y, x) = tupRetFn().expand;
```

IchorDev <zxinsworld gmail.com> writes:

On Saturday, 20 July 2024 at 20:48:29 UTC, Nick Treleaven wrote:
 Instead of the `tie` assignment, you can just do:
 ```d
 	import std.meta;
 	AliasSeq!(y, x) = tupRetFn().expand;
 ```

And here I was trying to use comma expressions for this like a 
buffoon! Of course they didn't work, but I'm pleasantly surprised 
that using a sequence does. I should really PR `std.typecons` to 
add a couple of examples of this, because I think a lot of people 
will have overlooked it.
I honestly thought there was no way to do this in D for the 
longest time until I saw some C++ code using `std::tie` and I 
realised that obviously the same thing is doable in D using 
`opAssign`, and then refined it to use UFCS because the syntax 
`Tie!(y,x)()` was a bit clunky.

Nick Treleaven <nick geany.org> writes:

On Sunday, 21 July 2024 at 04:05:52 UTC, IchorDev wrote:
 On Saturday, 20 July 2024 at 20:48:29 UTC, Nick Treleaven wrote:
 Instead of the `tie` assignment, you can just do:
 ```d
 	import std.meta;
 	AliasSeq!(y, x) = tupRetFn().expand;
 ```

 And here I was trying to use comma expressions for this like a 
 buffoon! Of course they didn't work, but I'm pleasantly 
 surprised that using a sequence does.

I think The lvalue sequence docs in template.dd were only updated 
in the last year to mention sequence assignment.

 I should really PR `std.typecons` to add a couple of examples 
 of this, because I think a lot of people will have overlooked 
 it.

Good idea.