https://run.dlang.io/is/p4NVp8

void main()
{
    import std.stdio: writefln;
    string[] s = ["a", "b", "c"];
    writefln("%(%s, %)", s);
}

output

"a", "b", "c"

expected

a, b, c

there is extra quotes, wich not present in firmat specifier.
is this bug, or i should change something in my code?

On Wednesday, 7 April 2021 at 13:31:59 UTC, novice3 wrote:

This is actually an intentional feature (albeit kind of a stupid one). From the documentation:

So, you should change your code to

writefln("%-(%s, %)", s);

On Wednesday, 7 April 2021 at 13:43:18 UTC, Paul Backus wrote:

writefln("%-(%s, %)", s);

sorry i dont read docs so carefully
thanks

On Wednesday, 7 April 2021 at 17:04:56 UTC, novice2 wrote:

writefln("%-(%s, %)", s);

It's not your fault--this is a pretty obscure feature, and it's not documented very well. Even after you've found the correct page in the documentation (the page for formattedWrite [1]), you have to scroll down past multiple examples to find the text that explains it.

[1] https://dlang.org/phobos/std_format.html#formattedWrite

On Wednesday, 7 April 2021 at 17:31:09 UTC, Paul Backus wrote:

The docs of std.format are currently under strong revision, about 90% is already done, but that "feature" is among the other 10%. I hope to get that ready till the end of the month, so the next stable release will have better docs.

Unfortunately it's much more difficult to change that strange behavior without breaking code. Currently I hope for Phobos 2.0 coming soon and meanwhile try to prepare std.format for that change.

On Wednesday, 7 April 2021 at 17:31:09 UTC, Paul Backus wrote:

writefln("%-(%s, %)", s);

I have created a pull request that will hopefully make this more prominent on the doc page:
https://github.com/dlang/phobos/pull/7944