Write to Any Slot (Solidity Code Example)

Solidity storage is like an array of length 2^256. Each slot in the array can store 32 bytes.

The order of declaration and the type of state variables define which slots it will use.

However, using assembly, you can write to any slot.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.26;

library StorageSlot {
    // Wrap address in a struct so that it can be passed around as a storage pointer
    struct AddressSlot {
        address value;
    }

    function getAddressSlot(bytes32 slot)
        internal
        pure
        returns (AddressSlot storage pointer)
    {
        assembly {
            // Get the pointer to AddressSlot stored at slot
            pointer.slot := slot
        }
    }
}

contract TestSlot {
    bytes32 public constant TEST_SLOT = keccak256("TEST_SLOT");

    function write(address _addr) external {
        StorageSlot.AddressSlot storage data =
            StorageSlot.getAddressSlot(TEST_SLOT);
        data.value = _addr;
    }

    function get() external view returns (address) {
        StorageSlot.AddressSlot storage data =
            StorageSlot.getAddressSlot(TEST_SLOT);
        return data.value;
    }
}