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Several fixes per Andreas's feedback

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Nemil Dalal 2015-11-24 00:09:10 -05:00
parent 08f3ee3687
commit 1f4738cbc7
1 changed files with 15 additions and 10 deletions
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solidity.html.markdown
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@ -14,28 +14,30 @@ As Solidity and Ethereum are under active development, experimental or beta feat
```javascript ```javascript
// Let's start with a simple Bank contract, before diving into to the key components of the language // Let's start with a simple Bank contract, before diving into to the key components of the language
// START EXAMPLE
// Start with a Natspec comment (the three slashes) that can be used // Start with a Natspec comment (the three slashes) that can be used
// for documentation - and as descriptive data for UI elements // for documentation - and as descriptive data for UI elements
/// @title A simple deposit/withdrawal bank built on Bitcoin /// @title A simple deposit/withdrawal bank built on Bitcoin
// All contracts are declared and named (in CamelCase) // All contracts are declared and named (in CamelCase)
// They are similar to 'class' in other languages (and allow capabilities like inheritance)
contract AcmeBank { contract AcmeBank {
// Declare state variables outside a function, // Declare state variables outside a function,
// these are persistent throughout the life of the contract // these are persistent throughout the life of the contract
// a dictionary that maps addresses to balances // a dictionary that maps addresses to balances
mapping (address -> uint) balances; mapping (address => uint) balances;
// the 'public' makes 'owner' externally readable by users or contracts // the 'public' makes 'owner' externally readable by users or contracts
// (but not writeable), the 'constant' means this value to be // (but not writeable), the 'constant' means this value to be
// changed after initialization // changed after initialization
address public constant owner; address public owner;
// Constructor, can receive one or many variables here // Constructor, can receive one or many variables here
function AcmeBank() { function AcmeBank() {
// msg is a default variable that provides both the // msg is a default variable that provides both the
// contract messager's address and amount // contract messager's address and amount
owner = msg.address; // msg.address refers to the address of the contract creator owner = msg.sender; // msg.sender refers to the address of the contract creator
} }
function deposit(uint balance) { function deposit(uint balance) {
@ -48,7 +50,7 @@ contract AcmeBank {
if(balances[msg.sender] >= withdrawAmount) { if(balances[msg.sender] >= withdrawAmount) {
balances[msg.sender] -= withdrawAmount; balances[msg.sender] -= withdrawAmount;
if (!balances[msg.sender].send(withdrawAmount)) { if (!msg.sender.send(withdrawAmount)) {
balances[msg.sender] += withdrawAmount; balances[msg.sender] += withdrawAmount;
} }
@ -56,7 +58,7 @@ contract AcmeBank {
} }
} }
// It's good practice to have a remove function, which disables this contract // It's good practice to have a remove function, which disables this contract - but does mean that users have to trust the owner
function remove () { function remove () {
if(msg.sender == owner) { // Only let the contract creator do this if(msg.sender == owner) { // Only let the contract creator do this
suicide(owner); // suicide makes this contract inactive, and returns funds to the owner suicide(owner); // suicide makes this contract inactive, and returns funds to the owner
@ -74,7 +76,7 @@ contract AcmeBank {
// otherwise, the sender loses their money; you should add this in most contracts // otherwise, the sender loses their money; you should add this in most contracts
function () { throw; } function () { throw; }
} }
// End example // END EXAMPLE
// Now let's go through the basics of Solidity // Now let's go through the basics of Solidity
@ -82,7 +84,7 @@ contract AcmeBank {
// uint is the data type typically used for currency (there are no doubles // uint is the data type typically used for currency (there are no doubles
// or floats) and for dates // or floats) and for dates
uint x; uint x;
int const a = 8; // int of 256 bits, cannot be changed after instantiation int constant a = 8; // int of 256 bits, cannot be changed after instantiation
uint8 b; uint8 b;
int64 c; int64 c;
// int256 is same as int // int256 is same as int
@ -134,7 +136,7 @@ names.length; // get length
names.length = 1; // lengths can also be set, unlike many other languages names.length = 1; // lengths can also be set, unlike many other languages
// Dictionaries (any type to any other type) // Dictionaries (any type to any other type)
mapping (string -> uint) public balances; mapping (string => uint) public balances;
balances["john"] = 1; balances["john"] = 1;
console.log(balances[jill]); // is 0, all non-set key values return zeroes console.log(balances[jill]); // is 0, all non-set key values return zeroes
// The 'public' lets you do the following from another contract // The 'public' lets you do the following from another contract
@ -322,13 +324,14 @@ suicide(SOME_ADDRESS); // suicide the current contract, sending funds to the add
// planning your data structures) // planning your data structures)
// *** EXAMPLE: Let's do a more complex example *** // *** EXAMPLE: Let's do a more complex example ***
// [TODO: Decide what a more complex example looks like, needs a few // characteristics: // [TODO: Decide what a more complex example looks like, needs a few characteristics:
// - has a 'constant' state variable // - has a 'constant' state variable
// - has a state machine (uses modifier) // - has a state machine (uses modifier)
// - sends money to an address // - sends money to an address
// - gets information from another contract (we'll show code for both contracts) // - gets information from another contract (we'll show code for both contracts)
// - Shows inheritance // - Shows inheritance
// - show variables being passed in on instantiation (and guard code to throw if variables not provided) // - show variables being passed in on instantiation (and guard code to throw if variables not provided)
// - Shows the swapping out of a contract
// Ideas: // Ideas:
// - crowdfunding? // - crowdfunding?
// - Peer to peer insurance // - Peer to peer insurance
@ -375,7 +378,9 @@ sha256("def");
// All data to the start of time is stored in the blockchain, so you and // All data to the start of time is stored in the blockchain, so you and
// anyone can observe all previous data states // anyone can observe all previous data states
// 9. STYLE NOTES // 9. TESTING
// 10. STYLE NOTES
// Use 4 spaces for indentation // Use 4 spaces for indentation
// (Python's PEP8 is used as the baseline style guide, including its general philosophy) // (Python's PEP8 is used as the baseline style guide, including its general philosophy)
``` ```