Hello,

I have "hello world" application. I imported std.file, executed thisExePath() and now I have this error:

----------------------------------------------------------------
dmd -m64 -of=../../bin/manager -release ./src/manager.d
/usr/include/dmd/phobos/std/file.d(3252): Error: readlink cannot be interpreted at compile time, because it has no available source code
/usr/include/dmd/phobos/std/file.d(3253):        called from here: delegate () => readlink(linkz.ptr(), & buffer, 2048LU)()
/usr/include/dmd/phobos/std/file.d(3433):        called from here: readLink("/proc/self/exe")
./src/manager.d(8):        called from here: thisExePath()
./src/manager.d(8):        called from here: dirName(thisExePath())
makefile:2: recipe for target 'all' failed
----------------------------------------------------------------

Whats going on? Why I cant build my executable file?

On Monday, 8 April 2019 at 18:38:58 UTC, 4544fa8d wrote:
>
> Whats going on? Why I cant build my executable file?

Did you put your code inside a main() function?

On Monday, 8 April 2019 at 18:38:58 UTC, 4544fa8d wrote:
> Hello,
>
> I have "hello world" application. I imported std.file, executed thisExePath() and now I have this error:
>
> ----------------------------------------------------------------
> dmd -m64 -of=../../bin/manager -release ./src/manager.d
> /usr/include/dmd/phobos/std/file.d(3252): Error: readlink cannot be interpreted at compile time, because it has no available source code
> /usr/include/dmd/phobos/std/file.d(3253):        called from here: delegate () => readlink(linkz.ptr(), & buffer, 2048LU)()
> /usr/include/dmd/phobos/std/file.d(3433):        called from here: readLink("/proc/self/exe")
> ./src/manager.d(8):        called from here: thisExePath()
> ./src/manager.d(8):        called from here: dirName(thisExePath())
> makefile:2: recipe for target 'all' failed
> ----------------------------------------------------------------
>
> Whats going on? Why I cant build my executable file?

The error message is telling you that dmd is trying to run readlink
at compile-time. But this is probably an extern (C) symbol that isn't
resolved except by the linker to some code in libc, which can only
happen after any compile-time computation's done.

Are you trying to get the /proc/self/exe of dmd itself?

On Monday, 8 April 2019 at 18:41:00 UTC, Adam D. Ruppe wrote:
> Did you put your code inside a main() function?

I want to make constant with path to directory containing executable. This line is above main():
-----------------------------
const ROOT_DIR = dirName(thisExePath());
-----------------------------

This is not allowed? :O

On Monday, 8 April 2019 at 18:47:42 UTC, 4544fa8d wrote:
> On Monday, 8 April 2019 at 18:41:00 UTC, Adam D. Ruppe wrote:
>> Did you put your code inside a main() function?
>
> I want to make constant with path to directory containing executable. This line is above main():
> -----------------------------
> const ROOT_DIR = dirName(thisExePath());
> -----------------------------
>
> This is not allowed? :O

That would give you dmd's path, if it worked.

This is allowed:

  #! /usr/bin/env rdmd
  import std.stdio, std.path, std.file;

  @property
  string root_dir() {
      static string cache;
      static bool isInit = false;
      if (!isInit) {
          isInit = true;
          cache = dirName(thisExePath());
      }
      return cache;
  }

  void main() {
      writeln(root_dir);
  }

On Monday, 8 April 2019 at 18:54:10 UTC, Julian wrote:
>   @property
>   string root_dir() {
>       static string cache;
>       static bool isInit = false;
>       if (!isInit) {
>           isInit = true;
>           cache = dirName(thisExePath());
>       }
>       return cache;
>   }

Shorter:

  string root_dir() {
      static string cache;
      return cache ? cache : (cache = dirName(thisExePath()));
  }

This might spam readlink() syscalls if they somehow return the empty string,
but how would that even happen...

On Monday, 8 April 2019 at 19:05:33 UTC, Julian wrote:
> Shorter:
>   string root_dir() {
>       static string cache;
>       return cache ? cache : (cache = dirName(thisExePath()));
>   }
> This might spam readlink() syscalls if they somehow return the

It's really not possible to call functions in modules like in any other languages? :S

---------------------------------------------------------------
import std.file;
import std.path;
import std.stdio;

//const ROOT_DIR = dirName(thisExePath());
int someInt = 0;
string someString = "sfgsdgdf";
writeln("one");

void main(){
	writeln("two");
}
---------------------------------------------------------------

On Monday, 8 April 2019 at 19:29:33 UTC, 4544fa8d wrote:
> It's really not possible to call functions in modules like in any other languages? :S

What some other languages do is collect all of those calls into an
implicit function that's called before main(). What D does is run
that code at compile-time. Silly example:

  import std.stdio;

  T twice(T)(T n) { return 2 * n; }

  auto x = twice(5);

  void main() {
      writeln(x);
  }

Take a look at the compiled result: https://godbolt.org/z/8vLsv9

There's a twice() that's compiled in, but if you look at x it's
already the result of a call to twice():

  int example.x:
          .long   10

and the (unoptimized) main just fetches that number to print.

On Monday, 8 April 2019 at 19:43:11 UTC, Julian wrote:
> On Monday, 8 April 2019 at 19:29:33 UTC, 4544fa8d wrote:
>> It's really not possible to call functions in modules like in any other languages? :S
>
> What some other languages do is collect all of those calls into an
> implicit function that's called before main(). What D does is run
> that code at compile-time.

Another way, from https://dlang.org/spec/module.html#staticorder

In thisexe.d:

  import std.stdio, std.path, std.file;

  public string root_dir;

  shared static this() {
      root_dir = dirName(thisExePath());
  }

In thisexe_ex.d:

  #! /usr/bin/env rdmd
  import thisexe, std.stdio;

  void main() {
      writeln(root_dir);
  }

does what you'd expect.