Re: Is there such concept of a list in D?

[areYouSureAboutThat via Digitalmars-d-learn]

On Saturday, 10 December 2022 at 06:11:18 UTC, thebluepandabear 
wrote:

I was wondering more if there is an object oriented way of 
creating arrays, like in Java there is an `ArrayList`, in C++ 
there is `std::vector`, etc.

of course there is - I mean just imagine if there wasn't ;-)

e.g (an note, it's called unsafeVector for a reason ;-)

// ----
module test;
import std;

void main()
{
    unsafeVector v = new unsafeVector(5);

    writefln("size of v is: %s", v.size());
    writeln;

    writeln("v contains:");
    for (int i = 0; i < v.size(); i++)
    {
        v[i] = i+1;
        writefln("v %s : %s", i , v[i]);
    }
    writeln;

    writeln(v[0..3]);
    writeln(v[0..$]);
    writeln(v[$-1]);
}

unittest
{
    unsafeVector v = new unsafeVector(5);

    assert(v.size() == 5);

    // NOTE: be sure to use the interface here
    // as D lets you shoot yourself in the foot
    // by giving you direct access to sz !!!
    for (int i = 0; i < v.size(); i++)
    {
        v[i] = i+1;
    }

    assert(v[0..3] == [1,2,3] );
    assert(v[0..$] == [1,2,3,4,5]);
    assert(v[$-1] == 5);

    v[2] = 999;
    assert(v[2] == 999);
}

class unsafeVector
{
  private:
    size_t *elem;
    immutable size_t sz;

  public:
    this(size_t s)
    {
        assert( isIntegral!(typeof(s)) );
        elem = cast(size_t*)new size_t[s];
        sz = s;
    }

    auto ref opIndex(size_t i)
    {
        return elem[i];
    }

    auto ref opSlice(size_t start, size_t end)
    {
        return elem[start .. end];
    }

    auto ref opDollar()
    {
        return sz;
    }

    auto size()
    {
        return sz;
    }
}
// ------------