No changes from the release candidate for this one, we’re ironing out the kinks from the release process!
This minor release includes a way to store token balances and supply so that they can be later queried in a gas-efficient manner , allows safe interaction with some old, non-compliant tokens , prevents user errors when using ECDSA signatures (the magic behind metatransactions! ), and provides multiple minor additions and improvements to the API.
To install the release run
npm install openzeppelin-solidity@latest.
We would love your help by reviewing newly added contracts, their interface and documentation so that we can make names clearer, features easier to use, and the library better as a whole! Your feedback is extremely useful to us
ERC20Snapshot: this variant allows for snapshots to be created on demand, storing the current token balances and total supply so that they can be later retrieved in a gas-efficient manner and e.g. calculate dividends at a past time. (#1617)
ERC20standard requires that all function calls (e.g.
approve, etc.) return a boolean value indicating success. However, they are multiple widely used tokens out there that return no such value: they simply
revertwhen encountering an error condition. Since Solidity v0.4.22, special code was needed to interact with this non-compliant tokens: now, all of
SafeERC20can be used to safely call both compliant and non-compliant tokens, without the developer having to worry about it. (#1655)
TimedCrowdsale: an internal
_extendTime(uint256 newClosingTime)function was added (with a corresponding
TimedCrowdsaleExtended(uint256 prevClosingTime, uint256 newClosingTime)event) allowing for users to safely develop mechanisms to extend the durations of unclosed crowdsales. Note that due to it being internal, there’s no out-of-the-box way to do it: this feature is opt-in and must be explicitly invoked by users.
recoverno longer accepts malleable signatures (those using upper-range values for
s, or 0/1 for
v). This helps prevent multiple issues when using signatures as unique identifiers. Read more about common ECDSA issues here. (#1622)
ERC721's transfers are now more gas efficient due to removal of unnecessary
safeApprovewasn’t properly checking for a zero allowance when attempting to set a non-zero allowance. This bug was reported independently by @nikeshnazareth. Thanks a lot! (#1647)
TokenMetadata(in drafts) has been renamed to
You can also see all details of this release in our changelog.