D: How do I pipe (|) through three programs using std.process?

[kdevel]

On Saturday, 18 November 2023 at 18:09:53 UTC, BoQsc wrote:
> Latest iteration on this thread.
>
> Limitations:
> * pipes through two programs.
> * very verbose, hard to use.
>

What exactly are you trying to achieve?

> ```
> import std;
> import std.process;
>
> version (Windows) { enum Find = "find"; }
> version (Posix) { enum Find = "grep"; }
>
> void pipeTo(Pipe p, string nextprogram){
> 	spawnShell(nextprogram, p.readEnd, stdout);
> ```

If you allow invoking the shell from within your program why 
don't you use one of its facilities, i.e. the shell's pipe 
operator `|`, in the first place? `spawnShell` does not execute 
`nextprogram` but it executes it under the shell.

> ```
>  }
>
> auto program(string name){
>     Pipe p = std.process.pipe;
> 	spawnShell(name, stdin, p.writeEnd);
>     return p;
> }
>
> void main()
> {
>     program("echo HelloWorld").pipeTo(nextprogram: Find ~ ` 
> "HelloWorld"`);

Have I missed the advent of named function arguments in D?

> ```
> }
> ```

Your whole program shrinks considerably:

```
import std;
import std.process;

version (Windows) { enum Find = "find"; }
version (Posix) { enum Find = "grep"; }
void main()
{
     spawnShell("echo HelloWorld | " ~ Find ~ ` 
"HelloWorld"`).wait;
}
```