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https://github.com/ethereum/solidity
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Merge pull request #616 from chriseth/docs
Removed some problems in documentation examples.
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chriseth
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@ -28,8 +28,6 @@ functions and this is what this page is about.
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The use of **function modifiers** makes these
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restrictions highly readable.
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.. {% include open_link gist="fe4ef267cbdeac151b98" %}
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::
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contract AccessRestriction {
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@ -167,8 +165,6 @@ function finishes.
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return. If you want to do that, make sure
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to call nextStage manually from those functions.
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.. {% include open_link gist="0a221eaceb6d708bf271" %}
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::
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contract StateMachine {
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@ -14,8 +14,6 @@ right now, we will go into more detail later.
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Storage
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=======
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.. Gist: a4532ce30246847b371b
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::
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contract SimpleStorage {
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@ -63,8 +61,6 @@ Furthermore, anyone can send coins to each other without any need for
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registering with username and password - all you need is an Ethereum keypair.
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.. Gist: ad490694f3e5b3de47ab
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::
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contract Coin {
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@ -34,8 +34,6 @@ At the end of the voting time, ``winningProposal()``
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will return the proposal with the largest number
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of votes.
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.. Gist: 618560d3f740204d46a5
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::
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/// @title Voting with delegation.
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@ -108,9 +106,17 @@ of votes.
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// Forward the delegation as long as
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// `to` also delegated.
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while (voters[to].delegate != address(0) &&
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voters[to].delegate != msg.sender) {
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to = voters[to].delegate;
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// In general, such loops are very dangerous,
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// because if they run too long, they might
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// need more gas than is available in a block.
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// In this case, the delegation will not be executed,
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// but in other situations, such loops might
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// cause a contract to get "stuck" completely.
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while (
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voters[to].delegate != address(0) &&
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voters[to].delegate != msg.sender
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) {
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to = voters[to].delegate;
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}
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// We found a loop in the delegation, not allowed.
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@ -199,8 +205,6 @@ contract has to be called manually for the
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beneficiary to receive his money - contracts cannot
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activate themselves.
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.. {% include open_link gist="48cd2b65ff83bd04f7af" %}
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::
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contract SimpleAuction {
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@ -215,6 +219,9 @@ activate themselves.
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address public highestBidder;
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uint public highestBid;
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// Allowed withdrawals of previous bids
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mapping(address => uint) pendingReturns;
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// Set to true at the end, disallows any change
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bool ended;
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@ -258,13 +265,29 @@ activate themselves.
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throw;
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}
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if (highestBidder != 0) {
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highestBidder.send(highestBid);
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// Sending back the money by simply using
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// highestBidder.send(highestBid) is a security risk
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// because it can be prevented by the caller by e.g.
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// raising the call stack to 1023. It is always safer
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// to let the recipient withdraw their money themselves.
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pendingReturns[highestBidder] += highestBid;
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}
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highestBidder = msg.sender;
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highestBid = msg.value;
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HighestBidIncreased(msg.sender, msg.value);
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}
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/// Withdraw a bid that was overbid.
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function withdraw() {
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var amount = pendingReturns[msg.sender];
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// It is important to set this to zero because the recipient
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// can call this function again as part of the receiving call
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// before `send` returns.
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pendingReturns[msg.sender] = 0;
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if (!msg.sender.send(amount))
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throw; // If anything fails, this will revert the changes above
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}
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/// End the auction and send the highest bid
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/// to the beneficiary.
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function auctionEnd() {
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@ -274,9 +297,8 @@ activate themselves.
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throw; // this function has already been called
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AuctionEnded(highestBidder, highestBid);
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// We send all the money we have, because some
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// of the refunds might have failed.
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beneficiary.send(this.balance);
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if (!beneficiary.send(highestBid))
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throw;
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ended = true;
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}
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@ -328,8 +350,6 @@ Bidders can confuse competition by placing several
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high or low invalid bids.
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.. {% include open_link gist="70528429c2cd867dd1d6" %}
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::
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contract BlindAuction {
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@ -349,6 +369,9 @@ high or low invalid bids.
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address public highestBidder;
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uint public highestBid;
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// Allowed withdrawals of previous bids
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mapping(address => uint) pendingReturns;
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event AuctionEnded(address winner, uint highestBid);
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/// Modifiers are a convenient way to validate inputs to
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@ -426,7 +449,8 @@ high or low invalid bids.
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// the same deposit.
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bid.blindedBid = 0;
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}
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msg.sender.send(refund);
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if (!msg.sender.send(refund))
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throw;
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}
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// This is an "internal" function which means that it
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@ -440,13 +464,24 @@ high or low invalid bids.
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}
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if (highestBidder != 0) {
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// Refund the previously highest bidder.
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highestBidder.send(highestBid);
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pendingReturns[highestBidder] += highestBid;
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}
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highestBid = value;
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highestBidder = bidder;
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return true;
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}
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/// Withdraw a bid that was overbid.
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function withdraw() {
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var amount = pendingReturns[msg.sender];
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// It is important to set this to zero because the recipient
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// can call this function again as part of the receiving call
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// before `send` returns.
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pendingReturns[msg.sender] = 0;
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if (!msg.sender.send(amount))
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throw; // If anything fails, this will revert the changes above
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}
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/// End the auction and send the highest bid
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/// to the beneficiary.
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function auctionEnd()
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@ -457,7 +492,8 @@ high or low invalid bids.
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AuctionEnded(highestBidder, highestBid);
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// We send all the money we have, because some
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// of the refunds might have failed.
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beneficiary.send(this.balance);
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if (!beneficiary.send(this.balance))
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throw;
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ended = true;
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}
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@ -472,8 +508,6 @@ high or low invalid bids.
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Safe Remote Purchase
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********************
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.. {% include open_link gist="b16e8e76a423b7671e99" %}
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::
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contract Purchase {
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@ -521,8 +555,9 @@ Safe Remote Purchase
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inState(State.Created)
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{
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aborted();
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seller.send(this.balance);
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state = State.Inactive;
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if (!seller.send(this.balance))
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throw;
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}
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/// Confirm the purchase as buyer.
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@ -545,9 +580,14 @@ Safe Remote Purchase
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inState(State.Locked)
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{
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itemReceived();
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buyer.send(value); // We ignore the return value on purpose
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seller.send(this.balance);
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// It is important to change the state first because
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// otherwise, the contracts called using `send` below
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// can call in again here.
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state = State.Inactive;
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// This actually allows both the buyer and the seller to
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// block the refund.
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if (!buyer.send(value) || !seller.send(this.balance))
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throw;
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}
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function() {
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