How to modify index being accessed in an array

Question

EDIT: in my case, it was easier to just check the bool value and if it was true, simply remove the first 0x200 (decimal 512) bytes from the array so any future access to the array wouldn't need to worry about it, basically meaning that if the bool "Skiphex200bytes" was true, I'd removes 0x200 bytes from the start of the array rather than have to modify the index being accessed on the fly. ill keep this question and the answer I declared to be correct since it's still useful information if anyone ever decides to do something similar.

Say I have 2 arrays: The one is

protected byte[] _ROM;

And the other is

public byte[] ROM => _ROM;

What if I wanted to make it so: when I try to get/set a value in ROM, (and if a certain bool is true) it adds 0x200 (decimal 512) to the index that's being requested, aka a kind of

return Boolvar ? ROM[i+0x200] : ROM[i]

within the getter/setter.

But I don't know how to access said index in the getter/setter, so I can't modify it before returning...

Either make the array into an object that overrides the indexer, or make this into a method call — Sami Kuhmonen, Jul 10 '20 at 13:02
Note: you actually have only *one* array. `ROM` is a read-only property providing access to the `_ROM` field. Both reference the same object. — dymanoid, Jul 10 '20 at 13:10

score 1 · Accepted Answer · answered Jul 10 '20 at 13:14

Declare a wrapper class that handles the indirection, something like:

public class RomRedirector
{
    private readonly byte[] _rom;

    internal RomRedirector(byte[] rom) => _rom = rom;

    public byte this[int index]
    {
        get => _rom[Redirect(index)];
        set => _rom[Redirect(index)] = value;
    }

    private int Redirect(int index) => Boolvar ? index + 0x200 : index;
    //                                   ^
    //                   this one needs to be rewritten/declared

    // add extra methods that you need from the array
}

Then use this one instead in your parent class:

public RomRedirector ROM { get; }

ROM = new RomRedirector(_ROM);

How to modify index being accessed in an array

1 Answers1