• Alec Stewart (63/63) Mar 28 2019 I'm sure something like this has been posted quite a bit, but I

Alec Stewart <alec-stewart protonmail.com> writes:

I'm sure something like this has been posted quite a bit, but I 
thought I'd try this for the heck of it.

Looking at unique_ptr.h, oof, that ugly. So this is what I have 
so far.

This to note

- since templates can't except function arguments, I thought I'd 
make use of alias arguments and AliasSeq
- since optional named arguments aren't a thing, I really have 
two options
   1. Have Func be null on initialization by, unless something is 
passed
   2. Make the template variadic
   The second of these two might actually be better.
- This is really basic and it's just the sole template at the 
moment.



///  Attempt to replicate C++'s unique_ptr, but a lot simpler.
///  Hopefully Better C compatiable as well.

import core.memory : __delete;
import std.stdio : writeln;
import std.typecons;
import std.traits;
import std.meta : AliasSeq;

/// This allows us to pass a function as an argument
/// for our pointer templates, and allows us to test
/// if a function (one that deletes, which we'll have to
/// figure a way to test for that later on) is passed to
/// our UniquePointer.
static auto ref SmartArgs(alias Thing, alias Func)()
{
     return Func(Thing);
}

/// The UniquePointer
/// Will delete whatever it references whenever it goes
/// out of scope. Pretty basic at the moment.
struct UniquePointer(alias Thing, alias Func)
{
      disable this();

     this(auto Thing, Func = null)
     {
         auto ptr = &Thing;
         auto func = Func.nullable;
         static assert(isVoid!ptr, "Cannot use something of an 
incomplete type");
         static assert(ptr.sizeof > 0, "Cannot use something of an 
incomplete type.");
     }

     ~this()
     {
         static if (!isNull!func && isFunction!func)
         {
             AliasSeq!(SmartArgs!(func, ptr));
         }
         else
         {
             writeln("No deletion function way provided, or what 
was provided wasn't a function.");
             scope (exit)
                 __delete(ptr);
         }
     }
}


This is a probably really complicated way of going about how to 
learn to use templates, but I just thought it'd be fun.