diff --git a/contracts/token/ERC721/README.adoc b/contracts/token/ERC721/README.adoc index 90ec73783..83547f213 100644 --- a/contracts/token/ERC721/README.adoc +++ b/contracts/token/ERC721/README.adoc @@ -7,18 +7,27 @@ This set of interfaces, contracts, and utilities are all related to the https:// TIP: For a walk through on how to create an ERC721 token read our xref:ROOT:erc721.adoc[ERC721 guide]. -The EIP consists of three interfaces, found here as {IERC721}, {IERC721Metadata}, and {IERC721Enumerable}. Only the first one is required in a contract to be ERC721 compliant. The core interface and the metadata extension are both implemented in {ERC721}. The enumerable extension is provided separately in {ERC721Enumerable}. +The EIP specifies four interfaces: -Additionally, {IERC721Receiver} can be used to prevent tokens from becoming forever locked in contracts. Imagine sending an in-game item to an exchange address that can't send it back!. When using <>, the token contract checks to see that the receiver is an {IERC721Receiver}, which implies that it knows how to handle {ERC721} tokens. If you're writing a contract that needs to receive {ERC721} tokens, you'll want to include this interface. +* {IERC721}: Core functionality required in all compliant implementation. +* {IERC721Metadata}: Optional extension that adds name, symbol, and token URI, almost always included. +* {IERC721Enumerable}: Optional extension that allows enumerating the tokens on chain, often not included since it requires large gas overhead. +* {IERC721Receiver}: An interface that must be implemented by contracts if they want to accept tokens through `safeTransferFrom`. -Additionally there are multiple custom extensions, including: +OpenZeppelin Contracts provides implementations of all four interfaces: -* designation of addresses that can pause token transfers for all users ({ERC721Pausable}). -* destruction of own tokens ({ERC721Burnable}). -* support for voting and vote delegation ({ERC721Votes}) +* {ERC721}: The core and metadata extensions, with a base URI mechanism. +* {ERC721Enumerable}: The enumerable extension. +* {ERC721Holder}: A bare bones implementation of the receiver interface. -NOTE: This core set of contracts is designed to be unopinionated, allowing developers to access the internal functions in ERC721 (such as <>) and expose them as external functions in the way they prefer. On the other hand, xref:ROOT:erc721.adoc#Presets[ERC721 Presets] (such as {ERC721PresetMinterPauserAutoId}) are designed using opinionated patterns to provide developers with ready to use, deployable contracts. +Additionally there are a few of other extensions: + +* {ERC721URIStorage}: A more flexible but more expensive way of storing metadata. +* {ERC721Votes}: Support for voting and vote delegation. +* {ERC721Pausable}: A primitive to pause contract operation. +* {ERC721Burnable}: A way for token holders to burn their own tokens. +NOTE: This core set of contracts is designed to be unopinionated, allowing developers to access the internal functions in ERC721 (such as <>) and expose them as external functions in the way they prefer. On the other hand, xref:ROOT:erc721.adoc#Presets[ERC721 Presets] (such as {ERC721PresetMinterPauserAutoId}) are designed using opinionated patterns to provide developers with ready to use, deployable contracts. == Core