Debug help - static foreach - module scope - Programming in D page 603

[Brother Bill]

On Thursday, 28 August 2025 at 13:16:26 UTC, Andy Valencia wrote:
> On Thursday, 28 August 2025 at 13:09:21 UTC, Brother Bill wrote:
>> Unable to compile.  Please advise.
>> ```
>> c:\dev\D\81 - 
>> 90\c83_e_static_foreach_fibonacci\source\app.d(8): Error: 
>> function declaration without return type. (Note that 
>> constructors are always named `this`)
>>     writeln(n);
>
> writeln() isn't valid at scope 0, which is where that static 
> foreach is putting it.  I changed it to pragma(msg, n) and saw 
> the expected sequence of numbers.
>
> Andy

What is "scope 0"?  is this same thing as module scope?

Refactored source/app.d

Output to console:  Why does static foreach run 'twice'?
```
pragma: 0
pragma: 2
pragma: 8
pragma: 34
pragma: 0
pragma: 2
pragma: 8
pragma: 34
main(): 0
main(): 2
main(): 8
main(): 34
```

source/app.d
```
import std.stdio;
import std.range;
import std.algorithm;

static foreach (n; FibonacciSeries().take(10).filter!isEven)
{
     // writeln not valid as module level (scope 0)
     pragma(msg, "pragma: ", n);
}

void main()
{
     foreach (n; FibonacciSeries().take(10).filter!isEven) {
         writeln("main(): ", n);
     }
}

bool isEven(int n) {
     return n % 2 == 0;
}

struct FibonacciSeries
{
     int current = 0;
     int next = 1;
     enum empty = false;
     int front() const
     {
         return current;
     }

     void popFront()
     {
         const nextNext = current + next;
         current = next;
         next = nextNext;
     }

     FibonacciSeries save() const
     {
         return this;
     }
}

```