Thread overview
container vs standard array
Sep 19
vino
Sep 19
JG
Sep 19
vino
September 19

Hi All,

I am trying to understand as to why the below code is throwing error

Code

import std.stdio: writeln;
import std.container.array;

void main () {
 //auto a = Array!string("Aname");           // throws error
 auto b = Array!char("Bname");             	// works
 auto c = Array!string("Aname", "Bname");  	// works

 //writeln(a);
 writeln("Container Array :", b);
 writeln("Container Array :", c);

 writeln();

 string[] d = ["Dname"];			       // works
 string[] e = ["Dname", "Ename"];              // works
 writeln("Standard Array :", d);
 writeln("Standard Array :", e);

}

From,
Vino

September 19

On Tuesday, 19 September 2023 at 00:34:01 UTC, vino wrote:

>

Hi All,

I am trying to understand as to why the below code is throwing error

Code

import std.stdio: writeln;
import std.container.array;

void main () {
 //auto a = Array!string("Aname");           // throws error
 auto b = Array!char("Bname");             	// works
 auto c = Array!string("Aname", "Bname");  	// works

 //writeln(a);
 writeln("Container Array :", b);
 writeln("Container Array :", c);

 writeln();

 string[] d = ["Dname"];			       // works
 string[] e = ["Dname", "Ename"];              // works
 writeln("Standard Array :", d);
 writeln("Standard Array :", e);

}

From,
Vino
Looks to me like when it receives a single range it expects the elements of that range to match the type. If I am correct in the first one if you replace the "Aname" by ["Aname"] it should work

September 19

On Tuesday, 19 September 2023 at 06:35:01 UTC, JG wrote:

>

On Tuesday, 19 September 2023 at 00:34:01 UTC, vino wrote:

>

//auto a = Array!string("Aname"); // throws error
auto b = Array!char("Bname"); // works
auto c = Array!string("Aname", "Bname"); // works
...
Looks to me like when it receives a single range it expects the elements of that range to match the type.

Yes, the first overload fails to match because U is inferred as immutable(char) rather than string:

this(U)(U[] values...)
if (isImplicitlyConvertible!(U, T))

This is because a single array can be passed to a typesafe variadic parameter rather than elements of that array type. And then immutable(char) doesn't convert to string.

I think a non-variadic overload could be added to make it work as expected.

September 19

On Tuesday, 19 September 2023 at 19:57:34 UTC, Nick Treleaven wrote:

>

This is because a single array can be passed to a typesafe variadic parameter rather than elements of that array type. And then immutable(char) doesn't convert to string.

I think a non-variadic overload could be added to make it work as expected.

https://github.com/dlang/phobos/pull/8818

September 19

On Tuesday, 19 September 2023 at 20:20:17 UTC, Nick Treleaven wrote:

>

On Tuesday, 19 September 2023 at 19:57:34 UTC, Nick Treleaven wrote:

>

This is because a single array can be passed to a typesafe variadic parameter rather than elements of that array type. And then immutable(char) doesn't convert to string.

I think a non-variadic overload could be added to make it work as expected.

https://github.com/dlang/phobos/pull/8818

Thank you very much.