*self.total_supply
owner: AccountId,
fn transfer_from(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool {
}
true
self.env().emit_event(Approval {
#[ink(topic)]
balances: storage::HashMap<AccountId, Balance>,
});
•授权事件
}
from: Some(from),
let owner = self.env().caller();
value: Balance,
ERC20界说了一些尺度的接口函数：balanceOf 、 totalSupply 、transfer 、transferFrom 、approve和allowance 。以及一些可选的字段，譬喻通证名称、标记以及小数保存位数等。
self.balances.insert(from, from_balance – value);return false
assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10);
to: Some(caller),
value: Balance,
allowances: storage::HashMap<(AccountId, AccountId), Balance>,
#[ink(topic)]
let to_balance = self.balance_of_or_zero(&to);
#[ink(message)]
#[ink(topic)]
}
self.allowances.insert((owner, spender), value);
}
let mut contract = Erc20::new(100);
struct Approval {
// 东西要领：若用户未被初始化，代币余额置为0
fn new_works() {
#[ink(event)]
#[ink(message)]
let from_balance = self.balance_of_or_zero(&from);
true
let caller = self.env().caller();
event Transfer(address indexed _from, address indexed _to, uint _value);
#[ink(topic)]
$ git clone [email protected]:paritytech/substrate.git
3.6 单位测试用例编写
#[ink(message)]
cargo-contract 0.6.1
// 获取合约接管者账户余额（代币吸收者账户大概未被初始化，通过此要领将其余额初始化为0）
fn total_supply(&self) -> Balance {
let caller = self.env().caller();
cargo contract BCOMMAND>
new Setup and create a new smart contract project
fn balance_of_or_zero(&self, owner: &AccountId) -> Balance {
#[ink(message)]
fn allowance(&self, owner: AccountId, spender: AccountId) -> Balance {
self.balances.insert(to, to_balance + value);
}
2.1 什么是ERC20尺度
let to_balance = self.balance_of_or_zero(&to);
self.balance_of_or_zero(&owner)
from: Option<AccountId>,
owner: AccountId,
*self.total_supply
struct Erc20 {
// 获取合约挪用者账户余额
}
build Compiles the smart contract
true
1.1 安装Substrate节点
struct Transfer {
from: Some(from),
Created contract erc20
fn transfer_from(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool {
#[ink::contract(version = “0.1.0”)]
spender: AccountId,
let from_balance = self.balance_of_or_zero(&from);
#[ink(storage)]
self.env().emit_event(Transfer {
……
mod tests {
to: Option<AccountId>,
help Prints this message or the help of the given subcommand(s)
}
}
});
#[ink(topic)]
•转账事件
}
Utilities to develop Wasm smart contracts
•合约结构事件
assert!(contract.transfer(AccountId::from([0x0; 32]), 10));
assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 0);
#[ink(message)]
}
}
spender: AccountId,
self.transfer_from_to(from, to, value)
contract ERC20 {
#[ink(message)]
}
fn new(&mut self, initial_supply: Balance) {
value: initial_supply,
fn transfer_from_to(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool {
self.transfer_from_to(from, to, value)
value,
}
（2）查询用户代币余额接口
#[cfg(test)]
}
fn total_supply(&self) -> Balance {
to: Some(caller),
use super::*;
self.balances.insert(caller, initial_supply);
fn balance_works() {
#[ink(message)]
#[test]
// (代币所有者, 代币授权利用者) -> 代币授权利用者可支配余额
切换到一个新分支 ‘v2.0.0-rc4’
panic = “abort” <– Panics shall be treated as aborts: reduces binary size
$ tree erc20/
assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
from: None,
3.4 合约接口要领建设
}
}
self.allowance_of_or_zero(&owner, &spender)
self.transfer_from_to(from, to, value)
test Test the smart contract off-chain
self.balances.insert(to, to_balance + value);
value: initial_supply,
assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
function totalSupply() constant returns (uint theTotalSupply);
fn balance_works() {
struct Erc20 {
3 ERC20合约开拓
详见：https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
#[ink(message)]
function transferFrom(address _from, address _to, uint _value) returns (bool success);
assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
执行呼吁后，会生成2个文件，个中lib.rs会包罗一些基本框架，我们可以在此基本上开拓我们的合约。
opt-level = “z” <– Optimize for small binary output
-h, –help Prints help information
value,
（4）授权转账——授权接口
let caller = self.env().caller();
#[test]
1.2 安装cargo contract插件
function allowance(address _owner, address _spender) constant returns (uint remaining);
（1）查询代币刊行总量接口
#[ink(message)]
#[test]
$ cd substrate
(v2.0.0-rc4)$ cargo build –release
total_supply: storage::Value<Balance>,
// 配置刊行总量
let contract = Erc20::new(777);
#[ink(event)]
}
#[ink(constructor)]
fn transfer_from_works() {
contract.approve(AccountId::from([0x1; 32]), 20);
fn allowance_of_or_zero(&self, owner: &AccountId, spender: &AccountId) -> Balance {
fn transfer(&mut self, to: AccountId, value: Balance) -> bool {
self.balances.insert(caller, initial_supply);
self.balances.insert(from, from_balance – value);
$ cargo contract –help
struct Erc20 {
});
fn balance_of(&self, owner: AccountId) -> Balance {
let allowance = self.allowance_of_or_zero(&from, &caller);
lto = true <– enable link-time-optimization: more efficient codegen
fn approve(&mut self, spender: AccountId, value: Balance) -> bool {
通过授权转账，挪用方可以授权指定账户，从其地点中安详的消费指定命量的代币。
/// The total supply.
}
function balanceOf(address _owner) constant returns (uint balance);
let contract = Erc20::new(777);
#[test]
fn balance_of_or_zero(&self, owner: &AccountId) -> Balance {
assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 0);
if allowance < value {
}
fn approve(&mut self, spender: AccountId, value: Balance) -> bool {
// 获取合约建设者
#[ink(message)]
value,
#[ink(event)]
}
// 给吸收地点转出指定金额代币
#[test]
}
/// 代币刊行总量
#[ink(topic)]
*self.allowances.get(&(*owner, *spender)).unwrap_or(&0)
（6）授权转账——转账接口
#[ink(storage)]
});
true
value: Balance,
SUBCOMMANDS:
}
return false
if from_balance < value {
// 获取合约接口挪用者地点
// 吸收者余额增加指定命量
•辅佐手册
（3）转账接口
}
// 合约建设者拥有所有刊行代币
spender,
generate-metadata Generate contract metadata artifacts
*self.balances.get(owner).unwrap_or(&0)
});
3.5 合约事件建设
from: None,
assert_eq!(contract.total_supply(), 100);
我们留意到，，在举办余额的增减时，并未像以太坊的solidity智能合约，利用特另外SafeMath接口，这是因为ink!提供了内置防溢出掩护，通过在Cargo.toml 设置文件中，添加如下设置来提供该安详机制：
（5）授权转账——余额查询
#[ink(topic)]
event Approval(address indexed _owner, address indexed _spender, uint _value);
*self.allowances.get(&(*owner, *spender)).unwrap_or(&0)
OPTIONS:
}
/// 用户及余额映射
value,
ERC20 通证尺度（ERC20 Token Standard）是通过建设通证时的一种类型。凭据 ERC20 的类型可以编写一个智能合约，建设“可交流畅证”。它并非强制要求，但遵循这个尺度，所建设的通证可以与浩瀚生意业务所、钱包等举办交互，它此刻已被行业普遍接管。[profile.release]
}
impl Erc20 {
assert_eq!(contract.total_supply(), 777);
#[test]
self.env().emit_event(Transfer {
#[ink(topic)]
(master)$ git checkout -b v2.0.0-rc4 v2.0.0-rc4
USAGE:
self.env().emit_event(Transfer {
self.allowances.insert((owner, spender), value);
self.balance_of_or_zero(&owner)
assert!(!contract.transfer(AccountId::from([0x0; 32]), 100));
to: Option<AccountId>,
}
use ink_core::storage;
self.total_supply.set(initial_supply);
erc20/
balances: storage::HashMap<AccountId, Balance>,
from: Option<AccountId>,
}
total_supply: storage::Value<Balance>,
$ cargo +nightly test }
if from_balance < value {
use ink_lang as ink;
fn new_works() {
spender,
});
}
struct Transfer {
#![cfg_attr(not(feature = “std”), no_std)]
}
return false
└── lib.rs
to: Some(to),
}
owner,
获代替币授权利用者剩余被答允转移的代币数量。
assert_eq!(contract.total_supply(), 777);
/// The balance of each user.
return false
value: Balance,
#[ink(constructor)]
•安装呼吁
#[ink(storage)]
fn balance_of(&self, owner: AccountId) -> Balance {
1 情况搭建
assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
let contract = Erc20::new(100);
2 ERC20合约先容
fn transfer_works() {
function transfer(address _to, uint _value) returns (bool success);
owner,
overflow-checks = true <– Arithmetic overflow protection
assert_eq!(contract.total_supply(), 100);
let caller = self.env().caller();
let mut contract = Erc20::new(100);
fn new(&mut self, initial_supply: Balance) {
self.allowances.insert((from, caller), allowance – value);
// 代币所有者(owner)授权代币利用者(spender)可支配余额(value)
答允智能合约自动执行转账流程并代表所有者发送给定命量的代币
#[test]
3.1 建设合约工程
跑测试用例：
fn allowance_of_or_zero(&self, owner: &AccountId, spender: &AccountId) -> Balance {
需完善合约存储：
#[ink(message)]
#[ink(topic)]
fn allowance(&self, owner: AccountId, spender: AccountId) -> Balance {
#[ink(event)]
let owner = self.env().caller();
}
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