diff options
author | Nemil Dalal <nemild@gmail.com> | 2015-11-24 00:09:10 -0500 |
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committer | Nemil Dalal <nemild@gmail.com> | 2015-11-24 00:09:10 -0500 |
commit | 1f4738cbc75f789992270c3926cf9cdd30c4674a (patch) | |
tree | a250b9a92dd1a34a418f47a13419977739a0c796 /solidity.html.markdown | |
parent | 08f3ee3687fc18286fdb3825f0fc1fd74c086798 (diff) |
Several fixes per Andreas's feedback
Diffstat (limited to 'solidity.html.markdown')
-rw-r--r-- | solidity.html.markdown | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/solidity.html.markdown b/solidity.html.markdown index bcbdec5f..88ccd817 100644 --- a/solidity.html.markdown +++ b/solidity.html.markdown @@ -14,28 +14,30 @@ As Solidity and Ethereum are under active development, experimental or beta feat ```javascript // 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 // for documentation - and as descriptive data for UI elements /// @title A simple deposit/withdrawal bank built on Bitcoin // All contracts are declared and named (in CamelCase) +// They are similar to 'class' in other languages (and allow capabilities like inheritance) contract AcmeBank { // Declare state variables outside a function, // these are persistent throughout the life of the contract // 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 // (but not writeable), the 'constant' means this value to be // changed after initialization - address public constant owner; + address public owner; // Constructor, can receive one or many variables here function AcmeBank() { // msg is a default variable that provides both the // 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) { @@ -48,7 +50,7 @@ contract AcmeBank { if(balances[msg.sender] >= withdrawAmount) { balances[msg.sender] -= withdrawAmount; - if (!balances[msg.sender].send(withdrawAmount)) { + if (!msg.sender.send(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 () { if(msg.sender == owner) { // Only let the contract creator do this 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 function () { throw; } } -// End example +// END EXAMPLE // 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 // or floats) and for dates 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; int64 c; // 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 // Dictionaries (any type to any other type) -mapping (string -> uint) public balances; +mapping (string => uint) public balances; balances["john"] = 1; console.log(balances[jill]); // is 0, all non-set key values return zeroes // 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) // *** 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 state machine (uses modifier) // - sends money to an address // - gets information from another contract (we'll show code for both contracts) // - Shows inheritance // - show variables being passed in on instantiation (and guard code to throw if variables not provided) +// - Shows the swapping out of a contract // Ideas: // - crowdfunding? // - 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 // anyone can observe all previous data states -// 9. STYLE NOTES +// 9. TESTING + +// 10. STYLE NOTES // Use 4 spaces for indentation // (Python's PEP8 is used as the baseline style guide, including its general philosophy) ``` |