EIP-1155 Adapter

Read this contract in master branch

This is an EIP-1155 wrapper contract of its reference implementation by Enjin (https://github.com/enjin/erc-1155). It is designed to be backward-compatible with existing interfaces, making it easier to adopt to token ecosystems.

Concepts

Some significant improvements over the original work are:

• ERC-20 compatibility: Calling createAdapter maps individual token to a separate ERC-20 token contract. The adapter contract makes it possible to interact with existing wallets, to be tradable on dapps like Uniswap, as a regular ERC-20 token.
• Proxy included: It is expensive to deploy an adapter for each individual token. To save gas, the typical solution is to keep a single adapter and deploy multiple proxies, forwarding any transactions to that adapter. Thanks to EIP-1167, we have a simple and canonical way to include a proxy contract. Proxy contracts are deployed with createClone function.
• Verbose events: To be distinguish from non-wrappers, it emits both TransferSingle and Transfer events when transferring with adapters.
• Additional checking bypass: In the reference implementation, when you attempt to transfer tokens to a contract address, it calls the function onERC1155Received at destination and requires its return value to be a magic number (=sha3(some_func_sig)) for safety. This is indeed a security mechanism, but it keep arbitrary contract addresses, like Gnosis Safes or mulit-sig wallets, from receiving ERC-1155 tokens. To better interoperate, the checking is not performed in this adapter.

The ideas are more clear when reading along with code.