Re: "%s"-format template function arguments
On 04/15/2018 02:04 PM, vladdeSV wrote:
foo(1,2,3);
void foo(T...)(T args)
{
writefln("expected: %s", [1,2,3]);
writefln("actual: %s", args);
}
The code above will output
expected: [1, 2, 3]
actual: 1
How would I go on about to print all the arguments as I expected it,
using "%s"?
writefln("%s", [args]);
Or avoiding the allocation:
import std.range: only;
writefln("%s", only(args));
You could also change the `args` parameter to give you a stack-based array:
void foo(T)(T[] args ...)
{
writefln("%s", args);
}
[...]
P.S.
I do not understand why only a `1` is printed in the actual result.
This:
writefln("actual: %s", args);
becomes this:
writefln("actual: %s", args[0], args[1], args[2]);
So there are three arguments after the format string. The %s placeholder
only refers to the first one. The others are ignored.
Re: "%s"-format template function arguments
On Sunday, 15 April 2018 at 12:04:19 UTC, vladdeSV wrote:
How would I go on about to print all the arguments as I
expected it, using "%s"?
You can expand the template arguments into an array by putting it
into square brackets: [args]. You can format an array with the
default notation using %s, for a custom format you can use %( and
%). See https://dlang.org/phobos/std_format.html
```
void main() {
foo(1, 2, 3);
}
void foo(T...)(T args) {
writefln("%s", [args]); // prints [1, 2, 3]
writefln("%(%s; %)", [args]); //custom ; separator, prints 1;
2; 3
}
```
Re: "%s"-format template function arguments
On Sunday, 15 April 2018 at 12:04:19 UTC, vladdeSV wrote:
Hello people of D-land.
In a template function, I want to format all arguments as if it
was an array. Se this snippet of code:
foo(1,2,3);
void foo(T...)(T args)
{
writefln("expected: %s", [1,2,3]);
writefln("actual: %s", args);
}
The code above will output
expected: [1, 2, 3]
actual: 1
How would I go on about to print all the arguments as I
expected it, using "%s"?
Best regards,
Vladimirs Nordholm
---
P.S.
I do not understand why only a `1` is printed in the actual
result.
If you define foo like that, then, you advice D to handle the
input as separate objects. That's ok. But then, you have to
define that you still assume, they belong together, like an array.
In this example the solution is simple:
´´´
void main()
{
foo(1,2,3);
}
void foo(T...)(T args)
{
import std.stdio : writefln;
import std.range : only;
writefln("expected: %s", [1,2,3]);
writefln("actual: %s", args.only);
}
´´´
However, there will be problems, if the types of elements
differs: While the template foo will be able to handle this, the
std.range : only function won't. It assumes at least something
common across them.
https://dlang.org/library/std/range/only.html
