I'm trying to use mixins to generate an array of numbers that are coprime to a statically known value. I've tried the following, but I receive the error:

Error: to(i) ~ ", " cannot be interpreted at compile time


string makePossibleAValues(string name, byte m) {
	string result = "immutable byte[] "~name~" = [";
	foreach (i; 0 .. m) {
		if (coprime(i, m)) {
			result ~= to!string(i) ~ ", ";
		}
	}
	return result ~ "];";
}

bool coprime(ulong a, ulong b) {
	return gcd(a, b) == 1;
}

ulong gcd(ulong a, ulong b) {
	while (b) {
		auto t = b;
		b = a % b;
		a = t;
	}
	return a;
}

mixin(makePossibleAValues("aValues", 26));


makePossibleAValues("aValues", 26) produces the correct result, "immutable byte[] aValues = [1, 3, 5, 7, 9, 11, 15, 17, 19, 21, 23, 25, ];", at runtime and I know to!string can be used in mixins. Any idea as to why this particular code is having trouble with to!string?

On 03/01/2011 07:58 AM, Peter Lundgren wrote:
> I'm trying to use mixins to generate an array of numbers that are coprime to a
> statically known value. I've tried the following, but I receive the error:
>
> Error: to(i) ~ ", " cannot be interpreted at compile time
>
>
> string makePossibleAValues(string name, byte m) {
> 	string result = "immutable byte[] "~name~" = [";
> 	foreach (i; 0 .. m) {
> 		if (coprime(i, m)) {
> 			result ~= to!string(i) ~ ", ";
> 		}
> 	}
> 	return result ~ "];";
> }
>
> bool coprime(ulong a, ulong b) {
> 	return gcd(a, b) == 1;
> }
>
> ulong gcd(ulong a, ulong b) {
> 	while (b) {
> 		auto t = b;
> 		b = a % b;
> 		a = t;
> 	}
> 	return a;
> }
>
> mixin(makePossibleAValues("aValues", 26));
>
>
> makePossibleAValues("aValues", 26) produces the correct result, "immutable
> byte[] aValues = [1, 3, 5, 7, 9, 11, 15, 17, 19, 21, 23, 25, ];", at runtime
> and I know to!string can be used in mixins. Any idea as to why this particular
> code is having trouble with to!string?

Not sure because I never use string mixins, but I guess the answer is precisely what the error says. Why don't you believe it?
makePossibleAValues() obviously returns a runtime value, so mixin() cannot evaluate it, I guess.

Denis
-- 
_________________
vita es estrany
spir.wikidot.com

On 3/1/11 7:58 AM, Peter Lundgren wrote:
> I'm trying to use mixins to generate an array of numbers that are coprime to a
> statically known value. I've tried the following, but I receive the error:
>
> Error: to(i) ~ ", " cannot be interpreted at compile time
> […]

Maybe I missed something as well, but to me it seems to be a CTFE bug, because if you split the offending line into two parts, it

result ~= to!string(i);
result ~= ", ";

Please consider filing this to Bugzilla.

David

On 3/1/11 11:45 AM, spir wrote:
> makePossibleAValues() obviously returns a runtime value, so mixin()
> cannot evaluate it, I guess.

Nope, that's not the problem due to CTFE (compile time function execution).

David

Peter Lundgren:

> I'm trying to use mixins to generate an array of numbers that are coprime to a statically known value. I've tried the following, but I receive the error:
> 
> Error: to(i) ~ ", " cannot be interpreted at compile time

Currently to!() can't run at compile-time.
Are you sure you need string mixings? Isn't compile-time run of functions enough for you?

If you really want to create that at compile-time as string, you are able to use the ToStringNow, converting makePossibleAValues into a recursive template, and running coprime() at compile-time from the template. But it will eat lot of RAM at compile-time.

Bye,
bearophile

David Nadlinger:

> Maybe I missed something as well, but to me it seems to be a CTFE bug, because if you split the offending line into two parts, it
> 
> result ~= to!string(i);
> result ~= ", ";
> 
> Please consider filing this to Bugzilla.

Wow. I was wrong, and you are right. It's not a problem of to!() then.

Bye,
bearophile

http://d.puremagic.com/issues/show_bug.cgi?id=5671

That worked, thanks. This is interesting because the example used in "The D Programming Language" on page 83 gets away with it just fine. I had no problem running this:

result ~= to!string(bitsSet(b)) ~ ", ";

On Tue, Mar 1, 2011 at 1:15 PM, Peter Lundgren <lundgrpb@rose-hulman.edu>wrote:

> That worked, thanks. This is interesting because the example used in "The D
> Programming Language" on page 83 gets away with it just fine. I had no
> problem
> running this:
>
> result ~= to!string(bitsSet(b)) ~ ", ";
>


How did you get that example on page 83 to compile?  I'm getting "undefined identifier bitsSet", and it's not in std.intrinsic or std.bitmanip.

On Fri, Mar 11, 2011 at 11:48 AM, Caligo <iteronvexor@gmail.com> wrote:

>
>
> On Tue, Mar 1, 2011 at 1:15 PM, Peter Lundgren <lundgrpb@rose-hulman.edu>wrote:
>
>> That worked, thanks. This is interesting because the example used in "The
>> D
>> Programming Language" on page 83 gets away with it just fine. I had no
>> problem
>> running this:
>>
>> result ~= to!string(bitsSet(b)) ~ ", ";
>>
>
>
> How did you get that example on page 83 to compile?  I'm getting "undefined identifier bitsSet", and it's not in std.intrinsic or std.bitmanip.
>

nvm, it's right there on that very page.