Update common-patterns.rst

docs/common-patterns.rst

@@ -28,7 +28,7 @@ become the new richest.
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract WithdrawalContract {
         address public richest;
@@ -70,7 +70,7 @@ This is as opposed to the more intuitive sending pattern:
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract SendContract {
         address public richest;
@@ -86,9 +86,7 @@ This is as opposed to the more intuitive sending pattern:
                 // Check if call succeeds to prevent an attacker
                 // from trapping the previous person's funds in
                 // this contract through a callstack attack
-                if (!richest.send(msg.value)) {
+                richest.transfer(msg.value);
-                    throw;
-                }
                 richest = msg.sender;
                 mostSent = msg.value;
                 return true;
@@ -135,7 +133,7 @@ restrictions highly readable.
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract AccessRestriction {
         // These will be assigned at the construction
@@ -152,8 +150,7 @@ restrictions highly readable.
         // a certain address.
         modifier onlyBy(address _account)
         {
-            if (msg.sender != _account)
+            require(msg.sender == _account);
-                throw;
             // Do not forget the "_;"! It will
             // be replaced by the actual function
             // body when the modifier is used.
@@ -169,7 +166,7 @@ restrictions highly readable.
         }
 
         modifier onlyAfter(uint _time) {
-            if (now < _time) throw;
+            require(now >= _time);
             _;
         }
 
@@ -190,8 +187,7 @@ restrictions highly readable.
         // This was dangerous before Solidity version 0.4.0,
         // where it was possible to skip the part after `_;`.
         modifier costs(uint _amount) {
-            if (msg.value < _amount)
+            require(msg.value >= _amount);
-                throw;
             _;
             if (msg.value > _amount)
                 msg.sender.send(msg.value - _amount);
@@ -276,7 +272,7 @@ function finishes.
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract StateMachine {
         enum Stages {
@@ -293,7 +289,7 @@ function finishes.
         uint public creationTime = now;
 
         modifier atStage(Stages _stage) {
-            if (stage != _stage) throw;
+            require(stage == _stage);
             _;
         }
 

docs/contracts.rst

@@ -327,7 +327,7 @@ inheritable properties of contracts and may be overridden by derived contracts.
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract owned {
         function owned() { owner = msg.sender; }
@@ -341,8 +341,7 @@ inheritable properties of contracts and may be overridden by derived contracts.
         // function is executed and otherwise, an exception is
         // thrown.
         modifier onlyOwner {
-            if (msg.sender != owner)
+            require(msg.sender == owner);
-                throw;
             _;
         }
     }
@@ -390,7 +389,7 @@ inheritable properties of contracts and may be overridden by derived contracts.
     contract Mutex {
         bool locked;
         modifier noReentrancy() {
-            if (locked) throw;
+            require(!locked);
             locked = true;
             _;
             locked = false;
@@ -401,7 +400,7 @@ inheritable properties of contracts and may be overridden by derived contracts.
         /// The `return 7` statement assigns 7 to the return value but still
         /// executes the statement `locked = false` in the modifier.
         function f() noReentrancy returns (uint) {
-            if (!msg.sender.call()) throw;
+            require(msg.sender.call());
             return 7;
         }
     }
@@ -989,7 +988,7 @@ more advanced example to implement a set).
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     library Set {
       // We define a new struct datatype that will be used to
@@ -1035,8 +1034,7 @@ more advanced example to implement a set).
             // The library functions can be called without a
             // specific instance of the library, since the
             // "instance" will be the current contract.
-            if (!Set.insert(knownValues, value))
+            assert(Set.insert(knownValues, value));
-                throw;
         }
         // In this contract, we can also directly access knownValues.flags, if we want.
     }
@@ -1166,7 +1164,7 @@ available without having to add further code.
 Let us rewrite the set example from the
 :ref:`libraries` in this way::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     // This is the same code as before, just without comments
     library Set {
@@ -1207,8 +1205,7 @@ Let us rewrite the set example from the
             // corresponding member functions.
             // The following function call is identical to
             // Set.insert(knownValues, value)
-            if (!knownValues.insert(value))
+            require(knownValues.insert(value));
-                throw;
         }
     }
 

docs/frequently-asked-questions.rst

@@ -665,8 +665,7 @@ What does the following strange check do in the Custom Token contract?
 
 ::
 
-    if (balanceOf[_to] + _value < balanceOf[_to])
+    require(balanceOf[_to] + _value >= balanceOf[_to]);
-        throw;
 
 Integers in Solidity (and most other machine-related programming languages) are restricted to a certain range.
 For ``uint256``, this is ``0`` up to ``2**256 - 1``. If the result of some operation on those numbers

docs/security-considerations.rst

@@ -79,7 +79,7 @@ outlined further below:
 
 ::
 
-  pragma solidity ^0.4.0;
+  pragma solidity ^0.4.11;
 
   contract Fund {
       /// Mapping of ether shares of the contract.
@@ -88,8 +88,7 @@ outlined further below:
       function withdraw() {
           var share = shares[msg.sender];
           shares[msg.sender] = 0;
-          if (!msg.sender.send(share))
+          require(msg.sender.send(share));
-              throw;
       }
   }
 
@@ -162,7 +161,7 @@ Never use tx.origin for authorization. Let's say you have a wallet contract like
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     // THIS CONTRACT CONTAINS A BUG - DO NOT USE
     contract TxUserWallet {
@@ -173,8 +172,8 @@ Never use tx.origin for authorization. Let's say you have a wallet contract like
         }
 
         function transfer(address dest, uint amount) {
-            if (tx.origin != owner) { throw; }
+            require(tx.origin == owner);
-            if (!dest.call.value(amount)()) throw;
+            require(dest.call.value(amount)());
         }
     }
 

docs/solidity-by-example.rst

@@ -36,7 +36,7 @@ of votes.
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     /// @title Voting with delegation.
     contract Ballot {
@@ -87,14 +87,12 @@ of votes.
         // Give `voter` the right to vote on this ballot.
         // May only be called by `chairperson`.
         function giveRightToVote(address voter) {
-            if (msg.sender != chairperson || voters[voter].voted) {
+            // `throw` terminates and reverts all changes to
-                // `throw` terminates and reverts all changes to
+            // the state and to Ether balances. It is often
-                // the state and to Ether balances. It is often
+            // a good idea to use this if functions are
-                // a good idea to use this if functions are
+            // called incorrectly. But watch out, this
-                // called incorrectly. But watch out, this
+            // will also consume all provided gas.
-                // will also consume all provided gas.
+            require(msg.sender == chairperson || !voters[voter].voted);
-                throw;
-            }
             voters[voter].weight = 1;
         }
 
@@ -102,12 +100,10 @@ of votes.
         function delegate(address to) {
             // assigns reference
             Voter sender = voters[msg.sender];
-            if (sender.voted)
+            require(!sender.voted);
-                throw;
 
             // Self-delegation is not allowed.
-            if (to == msg.sender)
+            require(to != msg.sender);
-                throw;
 
             // Forward the delegation as long as
             // `to` also delegated.
@@ -121,8 +117,7 @@ of votes.
                 to = voters[to].delegate;
 
                 // We found a loop in the delegation, not allowed.
-                if (to == msg.sender) 
+                require(to != msg.sender);
-                    throw;
             }
 
             // Since `sender` is a reference, this
@@ -145,8 +140,7 @@ of votes.
         /// to proposal `proposals[proposal].name`.
         function vote(uint proposal) {
             Voter sender = voters[msg.sender];
-            if (sender.voted)
+            require(!sender.voted);
-                throw;
             sender.voted = true;
             sender.vote = proposal;
 
@@ -218,7 +212,7 @@ activate themselves.
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract SimpleAuction {
         // Parameters of the auction. Times are either
@@ -269,16 +263,16 @@ activate themselves.
             // the transaction. The keyword payable
             // is required for the function to
             // be able to receive Ether.
-            if (now > auctionStart + biddingTime) {
+
-                // Revert the call if the bidding
+            // Revert the call if the bidding
-                // period is over.
+            // period is over.
-                throw;
+            require(now < auctionStart + biddingTime);
-            }
+            
-            if (msg.value <= highestBid) {
+
-                // If the bid is not higher, send the
+            // If the bid is not higher, send the
-                // money back.
+            // money back.
-                throw;
+            require(msg.value <= highestBid);
-            }
+            
             if (highestBidder != 0) {
                 // Sending back the money by simply using
                 // highestBidder.send(highestBid) is a security risk
@@ -327,18 +321,15 @@ activate themselves.
             // external contracts.
 
             // 1. Conditions
-            if (now <= auctionStart + biddingTime)
+            require(now >= auctionStart + biddingTime); // auction did not yet end
-                throw; // auction did not yet end
+            require(!ended); // this function has already been called
-            if (ended)
-                throw; // this function has already been called
 
             // 2. Effects
             ended = true;
             AuctionEnded(highestBidder, highestBid);
 
             // 3. Interaction
-            if (!beneficiary.send(highestBid))
+            require(beneficiary.transfer(highestBid));
-                throw;
         }
     }
 
@@ -381,7 +372,7 @@ high or low invalid bids.
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract BlindAuction {
         struct Bid {
@@ -409,8 +400,8 @@ high or low invalid bids.
         /// functions. `onlyBefore` is applied to `bid` below:
         /// The new function body is the modifier's body where
         /// `_` is replaced by the old function body.
-        modifier onlyBefore(uint _time) { if (now >= _time) throw; _; }
+        modifier onlyBefore(uint _time) { require(!now >= _time); _; }
-        modifier onlyAfter(uint _time) { if (now <= _time) throw; _; }
+        modifier onlyAfter(uint _time) { require(!now <= _time); _; }
 
         function BlindAuction(
             uint _biddingTime,
@@ -454,13 +445,11 @@ high or low invalid bids.
             onlyBefore(revealEnd)
         {
             uint length = bids[msg.sender].length;
-            if (
+            require(
-                _values.length != length ||
+                _values.length == length ||
-                _fake.length != length ||
+                _fake.length == length ||
-                _secret.length != length
+                _secret.length == length
-            ) {
+            );
-                throw;
-            }
 
             uint refund;
             for (uint i = 0; i < length; i++) {
@@ -481,8 +470,7 @@ high or low invalid bids.
                 // the same deposit.
                 bid.blindedBid = 0;
             }
-            if (!msg.sender.send(refund))
+            msg.sender.transfer(refund);
-                throw;
         }
 
         // This is an "internal" function which means that it
@@ -527,14 +515,12 @@ high or low invalid bids.
         function auctionEnd()
             onlyAfter(revealEnd)
         {
-            if (ended)
+            require(!ended);
-                throw;
             AuctionEnded(highestBidder, highestBid);
             ended = true;
             // We send all the money we have, because some
             // of the refunds might have failed.
-            if (!beneficiary.send(this.balance))
+            beneficiary.transfer(this.balance);
-                throw;
         }
     }
 
@@ -546,7 +532,7 @@ Safe Remote Purchase
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract Purchase {
         uint public value;
@@ -558,26 +544,26 @@ Safe Remote Purchase
         function Purchase() payable {
             seller = msg.sender;
             value = msg.value / 2;
-            if (2 * value != msg.value) throw;
+            require(!2 * value != msg.value);
         }
 
         modifier require(bool _condition) {
-            if (!_condition) throw;
+            require(_condition);
             _;
         }
 
         modifier onlyBuyer() {
-            if (msg.sender != buyer) throw;
+            require(msg.sender == buyer);
             _;
         }
 
         modifier onlySeller() {
-            if (msg.sender != seller) throw;
+            require(msg.sender == seller);
             _;
         }
 
         modifier inState(State _state) {
-            if (state != _state) throw;
+            require(state == _state);
             _;
         }
 
@@ -594,8 +580,7 @@ Safe Remote Purchase
         {
             aborted();
             state = State.Inactive;
-            if (!seller.send(this.balance))
+            seller.transfer(this.balance);
-                throw;
         }
 
         /// Confirm the purchase as buyer.
@@ -625,8 +610,7 @@ Safe Remote Purchase
             state = State.Inactive;
             // This actually allows both the buyer and the seller to
             // block the refund.
-            if (!buyer.send(value) || !seller.send(this.balance))
+            require(buyer.transfer(value) || seller.transfer(this.balance));
-                throw;
         }
     }
 

docs/structure-of-a-contract.rst

@@ -62,13 +62,13 @@ Function modifiers can be used to amend the semantics of functions in a declarat
 
 ::
 
-  pragma solidity ^0.4.0;
+  pragma solidity ^0.4.11;
 
   contract Purchase {
       address public seller;
 
       modifier onlySeller() { // Modifier
-          if (msg.sender != seller) throw;
+          require(msg.sender == seller);
           _;
       }
 

docs/types.rst

@@ -420,7 +420,7 @@ Example that shows how to use internal function types::
 
 Another example that uses external function types::
 
-    pragma solidity ^0.4.5;
+    pragma solidity ^0.4.11;
 
     contract Oracle {
       struct Request {
@@ -445,7 +445,7 @@ Another example that uses external function types::
         oracle.query("USD", this.oracleResponse);
       }
       function oracleResponse(bytes response) {
-        if (msg.sender != address(oracle)) throw;
+        require(msg.sender == address(oracle));
         // Use the data
       }
     }
@@ -722,7 +722,7 @@ shown in the following example:
 
 ::
 
-    pragma solidity ^0.4.0;
+    pragma solidity ^0.4.11;
 
     contract CrowdFunding {
         // Defines a new type with two fields.
@@ -763,8 +763,7 @@ shown in the following example:
                 return false;
             uint amount = c.amount;
             c.amount = 0;
-            if (!c.beneficiary.send(amount))
+            c.beneficiary.transfer(amount);
-                throw;
             return true;
         }
     }