Start Auction

In Solidity, startAuction usually relies on onlyOwner, mints an NFT into contract custody, then records auction metadata.

Solidity

function startAuction(...) external onlyOwner {
    require(maxPrice_ >= minPrice_, "invalid prices");
    require(duration_ > 0, "zero duration");
    _mint(address(this), nftId_);
    _auctions[nftId_] = Auction(...);
    emit AuctionCreated(nftId_);
}

Move

Move replaces the modifier with an explicit helper:

inline fun only_owner(owner: &signer) {
    assert!(
        signer::address_of(owner) == @dutch_auction_address,
        error::permission_denied(ENOT_OWNER)
    );
}

The main start_auction flow then:

1. checks ownership and arguments
2. creates the token object
3. creates the auction object
4. stores auction resources under that object
5. emits AuctionCreated

The important migration idea is that authorization, asset creation, and state-container creation are three explicit steps instead of one inherited contract action.