Forked from OZ.
This contract implements an upgradeable proxy. It is upgradeable because calls are delegated to an implementation address that can be changed. This address is stored in storage in the location specified by https://eips.ethereum.org/EIPS/eip-1967[EIP1967], so that it doesn’t conflict with the storage layout of the implementation behind the proxy.
constructor(address implementation, bytes _data) public payable_Initializes the upgradeable proxy with an initial implementation
specified by implementation.
If _data is nonempty, it’s used as data in a delegate
call to implementation. This will typically be an encoded
function call, and allows initializing the storage of the proxy like a
Solidity constructor.
Requirements:
_data is empty, msg.value must be
zero._function _implementation() internal view virtual returns (address)_Returns the current implementation address.
TIP: To get this value clients can read directly from the storage
slot shown below (specified by EIP1967) using the
https://eth.wiki/json-rpc/API#eth_getstorageat[eth_getStorageAt]
RPC call.
0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc_