The datafeed example from the ethereum dapp-bin standardized contract APIs, a single owner key value oracle.
Historical Significance
The ethereum.org token tutorial is where most people who deployed a token in this period started, and this is its opening form: a balance mapping, a guarded subtraction and the metadata a wallet needs to show a name. It has no allowance, so nothing can spend on a holder's behalf and no exchange or escrow can be given a limit. That gap is exactly what ERC-20 was written to close, and copies like this one are the before picture.
Context
Deployed 9 September 2015, during the Frontier era.
Key Facts
Description
The datafeed contract from the standardized contract APIs directory of the ethereum dapp-bin repository, one of the reference interfaces published so that early contracts could agree on how to read a price or a measurement from one another. The constructor records the deployer as owner. set takes a bytes32 key and a signed 256 bit value and writes it to storage when the caller is the owner; there is no else branch, so a call from anyone else succeeds and changes nothing. get returns the value stored under a key. get is declared as an ordinary function rather than a constant one, so a caller reading it through a transaction pays for the call even though it writes nothing.
Source Verified
Heuristic Analysis
The following characteristics were detected through bytecode analysis and may not be accurate.
Frontier Era
The initial release of Ethereum. A bare-bones implementation for technical users.
Bytecode Overview
Verified Source Available
Source verified through compiler archaeology and exact bytecode matching.
View Verification ProofShow source code (Solidity)
// Submitted by EthereumHistory (ethereumhistory.com)
contract datafeed {
mapping ( bytes32 => int256 ) data;
address owner;
function datafeed() {
owner = msg.sender;
}
function set(bytes32 k, int256 v) {
if (owner == msg.sender)
data[k] = v;
}
function get(bytes32 k) returns (int256 v) {
v = data[k];
}
}External Links
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