I tried:

import std.stdio;
void main()
{
	int [5] vals = [1, 2, 3, 4, 5];
	writefln("A = %d, B = %d, C = %d, D = %d, E = %d", vals []);
}

but got thrown an exception that "%d is not a valid specifier for a range".

The Python equivalent to flatten a list works:

vals = [1, 2, 3, 4, 5]
print("A = {}, B = {}, C = {}, D = {}, E = {}".format(*vals))

Output:

A = 1, B = 2, C = 3, D = 4, E = 5

Question:

Can D's [] be made to work that way? I recently had to write custom functions since I had an array representing numerical fields and wanted to print them out with individual labels but I wasn't able to use a single writefln with sufficient specifiers for that purpose because of this limitation.

-- 
Shriramana Sharma, Penguin #395953

On Thursday, 22 October 2015 at 15:57:05 UTC, Shriramana Sharma wrote:
> I tried:
>
> import std.stdio;
> void main()
> {
> 	int [5] vals = [1, 2, 3, 4, 5];
> 	writefln("A = %d, B = %d, C = %d, D = %d, E = %d", vals []);
> }
>
> but got thrown an exception that "%d is not a valid specifier for a range".
>
> The Python equivalent to flatten a list works:
>
> vals = [1, 2, 3, 4, 5]
> print("A = {}, B = {}, C = {}, D = {}, E = {}".format(*vals))
>
> Output:
>
> A = 1, B = 2, C = 3, D = 4, E = 5
>
> Question:
>
> Can D's [] be made to work that way? I recently had to write custom functions since I had an array representing numerical fields and wanted to print them out with individual labels but I wasn't able to use a single writefln with sufficient specifiers for that purpose because of this limitation.

D's `writefln` is a template-variadic function. Each time you use it, the compiler looks at the arguments you send to it, and compiles a new instantiation of it based on the number and types of these arguments. This means that it would have to know at compile time how many values `vals[]` holds - but that number is only known at runtime!

Now, in your case, since vals is a static array, it should be possible to know it's value at compile time. Maybe if there was a `tupleof` for static arrays?

At any rate, you can always use the range formatters %( and %) to print the array. See http://dpaste.dzfl.pl/47e3e5a9e5c4

On Thursday, 22 October 2015 at 17:19:07 UTC, Idan Arye wrote:
> Now, in your case, since vals is a static array, it should be possible to know it's value at compile time. Maybe if there was a `tupleof` for static arrays?

Ask and ye shall receive.

http://forum.dlang.org/post/gkdqakdogqevwzntpgtu@forum.dlang.org

On 22-Oct-2015 18:57, Shriramana Sharma wrote:
> I tried:
>
> import std.stdio;
> void main()
> {
> 	int [5] vals = [1, 2, 3, 4, 5];
> 	writefln("A = %d, B = %d, C = %d, D = %d, E = %d", vals []);
> }
>
> but got thrown an exception that "%d is not a valid specifier for a range".
>
> The Python equivalent to flatten a list works:
>
> vals = [1, 2, 3, 4, 5]
> print("A = {}, B = {}, C = {}, D = {}, E = {}".format(*vals))
>
> Output:
>
> A = 1, B = 2, C = 3, D = 4, E = 5
>
> Question:
>
> Can D's [] be made to work that way? I recently had to write custom
> functions since I had an array representing numerical fields and wanted to
> print them out with individual labels but I wasn't able to use a single
> writefln with sufficient specifiers for that purpose because of this
> limitation.


Hm writeln supportы cool printing of any range might be not quite what you want though.

e.g.

auto arr = [1.23, 5.46, 6.21, 7.7711, 9.81121];
writeln("%(%.2f, %)", arr); // would print coma separated list



-- 
Dmitry Olshansky