EOSIO Developer Portal 解説　独自トークンの発行 第1回

はじめに

eosio.tokenコントラクト

コードのダウンロード

$ cd CONTRACTS_DIR
 
$ git clone https://github.com/EOSIO/eosio.contracts --branch v1.4.0 --single-branch
 
$ cd eosio.contracts/eosio.token
 
# treeコマンドがない場合は sudo apt install tree でインストール
# macOSなら brew install tree でもインストール可
$ tree
.
├── CMakeLists.txt
├── README.md
├── include
│   └── eosio.token
│       └── eosio.token.hpp
└── src
    └── eosio.token.cpp

コントラクトの構造

class [[eosio::contract("eosio.token")]] token : public contract {
   public:
      using contract::contract;
 
      [[eosio::action]]
      void create( name   issuer,
                   asset  maximum_supply);
 
      [[eosio::action]]
      void issue( name to, asset quantity, string memo );
 
      [[eosio::action]]
      void retire( asset quantity, string memo );
 
      [[eosio::action]]
      void transfer( name    from,
                     name    to,
                     asset   quantity,
                     string  memo );
 
      [[eosio::action]]
      void open( name owner, const symbol& symbol, name ram_payer );
 
      [[eosio::action]]
      void close( name owner, const symbol& symbol );
};

private:
   struct [[eosio::table]] account {
      asset    balance;
 
      uint64_t primary_key()const { return balance.symbol.code().raw(); }
   };
 
   struct [[eosio::table]] currency_stats {
      asset    supply;
      asset    max_supply;
      name     issuer;
 
      uint64_t primary_key()const { return supply.symbol.code().raw(); }
   };
 
   typedef eosio::multi_index< "accounts"_n, account > accounts;
   typedef eosio::multi_index< "stat"_n, currency_stats > stats;

コントラクトのデプロイ

$ eosio-cpp --version
eosio-cpp version 1.3.2

$ docker start eosio
eosio
 
$ docker ps
CONTAINER ID        IMAGE               COMMAND                ...
50f1aabd7a1c        eosio/eos:v1.4.2    "/bin/bash -c 'keosd…" ...

# defaultウォレットを開く
$ cleos wallet open
Opened: default
 
# ウォレットの一覧を確認
$ cleos wallet list
Wallets:
[
  "default"
]
 
# パスワードを用いてウォレットをアンロック
$ cleos wallet unlock
password:
 
# もう一度ウォレットの一覧を確認
$ cleos wallet list
Wallets:
[
  "default *"  # * がついていることで、ウォレットがアンロックされている
]
 
# ウォレットの公開鍵と秘密鍵を確認
$ cleos wallet private_keys
password:
[[
    "YOUR_PUBLIC_KEY",
    "YOUR_PRIVATE_KEY"
  ],[
    "EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV",
    "5KQwrPbwdL6PhXujxW37FSSQZ1JiwsST4cqQzDeyXtP79zkvFD3"
  ]
]

$ cleos get accounts YOUR_PUBLIC_KEY
{
  "account_names": [
    "alice",
    "bob",
    "hello"
  ]
}

$ cleos create account eosio eosio.token \
EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV

$ cleos get accounts EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV
{
  "account_names": [
    "eosio.token"
  ]
}

コントラクトのデプロイ

$ eosio-cpp -I include -o eosio.token.wasm src/eosio.token.cpp --abigen
$ ls -l
CMakeLists.txt
README.md
eosio.token.abi
eosio.token.wasm
include
src

$ cleos set contract eosio.token CONTRACTS_DIR/eosio.contracts/eosio.token --abi eosio.token.abi -p eosio.token@active
 
Reading WASM from ...
Publishing contract...
executed transaction: 69c68b1bd5d61a0cc146b11e89e11f02527f24e4b240731c4003ad1dc0c87c2c  9696 bytes  6290 us
#         eosio <= eosio::setcode               {"account":"eosio.token","vmtype":0,"vmversion":0,"code":"0061736d0100000001aa011c60037f7e7f0060047f...
#         eosio <= eosio::setabi                {"account":"eosio.token","abi":"0e656f73696f3a3a6162692f312e30000605636c6f73650002056f776e6572046e61...
warning: transaction executed locally, but may not be confirmed by the network yet         ]

新規トークンの作成

void token::create( name   issuer,
                    asset  maximum_supply )
{
    require_auth( _self );
 
    auto sym = maximum_supply.symbol;
    eosio_assert( sym.is_valid(), "invalid symbol name" );
    eosio_assert( maximum_supply.is_valid(), "invalid supply");
    eosio_assert( maximum_supply.amount > 0, "max-supply must be positive");
 
    stats statstable( _self, sym.code().raw() );
    auto existing = statstable.find( sym.code().raw() );
    eosio_assert( existing == statstable.end(), "token with symbol already exists" );
 
    statstable.emplace( _self, [&]( auto& s ) {
       s.supply.symbol = maximum_supply.symbol;
       s.max_supply    = maximum_supply;
       s.issuer        = issuer;
    });
}

$ cleos push action eosio.token create '[ "eosio", "1000000000.0000 SYS"]' -p eosio.token@active
 
executed transaction: 0e49a421f6e75f4c5e09dd738a02d3f51bd18a0cf31894f68d335cd70d9c0e12  120 bytes  1000 cycles
#   eosio.token <= eosio.token::create          {"issuer":"eosio","maximum_supply":"1000000000.0000 SYS"}

$ cleos push action eosio.token create '[ "eosio", "1000000000 YEN"]' -p eosio.token@active
 
executed transaction: 487d3838a96f7389029929fa41a8249c37f35216de0110a07a4c6cb129fc31d4  120 bytes  1407 us
#   eosio.token <= eosio.token::create          {"issuer":"eosio","maximum_supply":"1000000000 YEN"}

$ cleos get table eosio.token SYS stat
{
  "rows": [{
      "supply": "0 SYS",
      "max_supply": "1000000000.0000 SYS",
      "issuer": "eosio"
    }
  ],
  "more": false
}
 
$ cleos get table eosio.token YEN stat
{
  "rows": [{
      "supply": "0 YEN",
      "max_supply": "1000000000 YEN",
      "issuer": "eosio"
    }
  ],
  "more": false
}

参考文献：

• EOSIO Developer Portal – 2.2 Deploy, Issue and Transfer Tokens
  https://developers.eos.io/eosio-home/docs/token-contract
• B9lab Academy – Introduction to EOSIO for Developers
  https://academy.b9lab.com/courses/course-v1:B9lab+EOSIO-FREE+2018-09/about
• Understanding The eosio.token Contract
  https://medium.com/coinmonks/understanding-the-eosio-token-contract-87466b9fdca9