PlatON WASM合约开发（二）—— 跨合约调用

概述#

基于PlatON进行生态开发，智能合约是关键。这篇文章将会为大家介绍PlatON WASM智能合约的跨合约调用。本教程将用到我们在入门篇中（做成超链接）教程内容，如果还没有安装开发环境，或者还未进行合约部署，可以参见入门篇。

合约开发#

编写合约#

代码#

在contracts目录下新建文件Cross.cpp，合约内容如下：

#undef NDEBUG#include <platon/platon.hpp>#include <string>using namespace platon;
CONTRACT Cross : public platon::Contract{public:    ACTION void init(){}
    ACTION void add_message(std::string a, std::string b, std::string c)    {        auto address_pair = make_address("lat150nn0efn0de86mw2pcdyhlnmucln89m93sr49h");        char param[50];        sprintf(param, "[[[\"&s\"], \"&s\", \"&s\"]]", a.c_str(), b.c_str(), c.c_str());        auto result = platon_call(address_pair.first, uint32_t(0), uint32_t(0), "add_message", std::string(param));        if (!result)        {            internal::platon_throw("add_message fail");        }    }
    CONST uint8_t get_message_size()    {        auto address_pair = make_address("lat150nn0efn0de86mw2pcdyhlnmucln89m93sr49h");        if (address_pair.second)        {            DEBUG("address", address_pair.first.toString())        }        else        {            DEBUG("address error")        }        auto result = platon_call_with_return_value<uint8_t>(address_pair.first,                                                uint32_t(0), uint32_t(0), "get_message_size");        if (!result.second)        {            internal::platon_throw("cross call fail");        }        return result.first;    }
    CONST std::string get_message_body(const uint8_t index)    {        auto address_pair = make_address("lat150nn0efn0de86mw2pcdyhlnmucln89m93sr49h");        auto result = platon_call_with_return_value<std::string>(address_pair.first, uint32_t(0), uint32_t(0), "get_message_body", index);        if (!result.second)        {            internal::platon_throw("cross call fail");        }        return result.first;    }};
PLATON_DISPATCH(Cross, (init)(add_message)(get_message_size)(get_message_body))

代码说明#

代码中我们用到了platon_call和platon_call_with_return_value方法，分别表示无返回调用和有返回合约调用。
更多的接口可以在~/.config/truffle/compilers/platon-cdt/platon.cdt/include/platon目录中找到，如合约调用文件为cross_call.hpp。
make_address填入的地址是HelloWorld教程中部署的合约地址。
make_address函数返回的是一个pair，需要根据second值判断地址是否获取成功。
DEBUG可以用于调试输出，可以在节点日志中看到输出信息。需要修改"lat150nn0efn0de86mw2pcdyhlnmucln89m93sr49h"为之前部署的HelloWorld合约地址

编译#

注意#

官方目前只发布了alaya版本的wasm编译器，在涉及到跨合约调用的时候，会出现地址编码问题，因此需要手动编译和安装platon版本的wasm编译器。我们已经编译了最新版本的platon版本的wasm编译器，有需要的朋友可以下载并解压到~/.config/truffle/compilers目录下。

执行编译命令#

platon-truffle compile

部署#

platon-truffle deploy --wasm --contract-name Cross

署成功后，将看到类似如下信息：

receipt:  { blockHash:   '0x8602678fc1f9e1934e9505fc291e3021e5eff70513d37156bc9b9b87273cfb69',  blockNumber: 3957166,  contractAddress: 'lat1ypc40ulq7vqk2kle0wcr7gf2udlgkwpsta5e0d',  cumulativeGasUsed: 322472,  from: 'lat1ar0s6re3qpe3rt39523qw4jars6s4sdhak459n',  gasUsed: 322472,  logs: [],  logsBloom:   '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',  status: true,  to: null,  transactionHash:   '0xf0a04748ca277ec7ceecc2910753bec270f802632d2743843b43cc8030a73bd8',  transactionIndex: 0 }contract Cross deployed successfully======================
   > transactionHash:     0xf0a04748ca277ec7ceecc2910753bec270f802632d2743843b43cc8030a73bd8   > contract address:    lat1ypc40ulq7vqk2kle0wcr7gf2udlgkwpsta5e0d   > block number:        3957166   > block timestamp:     1619603861743   > account:             lat1ar0s6re3qpe3rt39523qw4jars6s4sdhak459n   > balance:             7199474719087690925044   > gas limit:           9424776   > gas used:            322472   > gas price:           0.00000002 LAT   > total cost:          0.00644944 LAT

测试#

1. 进入platon-truffle控制台#

platon-truffle console

*以下调用查询将在truffle控制台中进行

2. 构建合约对象#

var abi = [{"constant":true,"input":[],"name":"get_message_size","output":"uint8","type":"Action"},{"constant":false,"input":[],"name":"init","output":"void","type":"Action"},{"constant":false,"input":[{"name":"a","type":"string"},{"name":"b","type":"string"},{"name":"c","type":"string"}],"name":"add_message","output":"void","type":"Action"},{"constant":true,"input":[{"name":"index","type":"uint8"}],"name":"get_message_body","output":"string","type":"Action"}];
var contractAddr = 'lat1ypc40ulq7vqk2kle0wcr7gf2udlgkwpsta5e0d'; var cross = new web3.platon.Contract(abi,contractAddr,{vmType: 1 });

说明：#

abi是合约提供给外部调用时的接口，每个合约对应的abi在编译后的文件中，如：HelloWorld/build/contracts/Cross.abi.json中可以找到
contractAddr在部署合约成功后有一个contract address
cross就是构建出来与链上合约交互的合约对象抽象

3. 调用合约#

cross.methods.add_message("10", "11", "12").send({    from: 'lat1ar0s6re3qpe3rt39523qw4jars6s4sdhak459n',gas: 999999}).on('receipt', function(receipt) {    console.log(receipt);}).on('error', console.error);

调用合约命令说明：#

cross是之前构建的合约对象
methods固定语法,后面紧跟合约的方法名
add_message是我们Cross合约中的一个方法，有3个std::string类型的入参
from调用者的钱包地址
gasgas值
on是监听合约处理结果事件，此处如果成功将打印回执，失败输出错误日志函数调用成功，将会看到如下信息：

{ blockHash:   '0x50fac24f50f871260663997d66f99e7d4e66bd09edc3002cc00d2be8c0021bdc',  blockNumber: 3957919,  contractAddress: null,  cumulativeGasUsed: 137365,  from: 'lat1ar0s6re3qpe3rt39523qw4jars6s4sdhak459n',  gasUsed: 137365,  logsBloom:   '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',  status: true,  to: 'lat1ypc40ulq7vqk2kle0wcr7gf2udlgkwpsta5e0d',  transactionHash:   '0x8196f89cca8161b940b649008211c1cccea40edf0581d5088961c344382d3f31',  transactionIndex: 0,  events: {} }

4. 查询合约#

get_message_body#

cross.methods.get_message_body(0).call()

查询合约命令说明：#

cross是之前构建的合约对象
methods指定将获取合约中的方法
get_message_body是我们HelloWorld合约中的一个方法，该方法有一个int类型的入参 call指明是查询方法

get_message_size#

cross.methods.get_message_size().call()

查询合约命令说明：#

cross是之前构建的合约对象
methods指定将获取合约中的方法
get_message_size是我们HelloWorld合约中的一个方法，该方法没有参数 call指明是查询方法

想要获得更多关于合约开发的资料，请前往官网文档。

本教程贡献者 @xiyu