Fixing a smart contract written in old version of eosio.cdt

Question

I am using Ubuntu 18.04 LTS first of all.

So I am trying to look up how to start building an EOS dApp, starting with this example on Github.

Here is the link: https://github.com/eosasia/eos-todo

I cloned the repository and tried to run it by deploying the todo.cpp file which is inside the contract folder.

The whole code for todo.cpp is here:

#include <eosiolib/eosio.hpp>
#include <eosiolib/print.hpp>

class todo_contract : public eosio::contract {
  public:
    todo_contract(account_name self)
      :eosio::contract(self),
      todos(_self, _self)
      {}

    // @abi action
    void create(account_name author, const uint32_t id, const std::string& description) {
      todos.emplace(author, [&](auto& new_todo) {
        new_todo.id  = id;
        new_todo.description = description;
        new_todo.completed = 0;
      });

      eosio::print("todo#", id, " created");
    }

    // @abi action
    void destroy(account_name author, const uint32_t id) {
      auto todo_lookup = todos.find(id);
      todos.erase(todo_lookup);

      eosio::print("todo#", id, " destroyed");
    }

    // @abi action
    void complete(account_name author, const uint32_t id) {
      auto todo_lookup = todos.find(id);
      eosio_assert(todo_lookup != todos.end(), "Todo does not exist");

      todos.modify(todo_lookup, author, [&](auto& modifiable_todo) {
        modifiable_todo.completed = 1;
      });

      eosio::print("todo#", id, " marked as complete");
    }

  private:
    // @abi table todos i64
    struct todo {
      uint64_t id;
      std::string description;
      uint64_t completed;

      uint64_t primary_key() const { return id; }
      EOSLIB_SERIALIZE(todo, (id)(description)(completed))
    };

    typedef eosio::multi_index<N(todos), todo> todo_table;
    todo_table todos;
};

EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))

I tried to build wast and abi file from it for the first step but there are 4 errors coming up when I type

eosio-cpp -o todo.wast todo.cpp && eosio-cpp -g todo.abi todo.cpp

in the Terminal.

The 4 errors I have got are:

todo.cpp:57:40: error: unknown type name 'complete'
EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))
                                       ^
todo.cpp:57:50: error: unknown type name 'destroy'
EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))
                                                 ^
todo.cpp:57:32: error: C++ requires a type specifier for all declarations
EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))
                               ^
todo.cpp:57:59: error: expected function body after function declarator
EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))
                                                          ^
4 errors generated.

I have googled many times but could not find the solution yet.

Any help I can use about this problem? Thanks in advance!

todo.cpp:9:10: error: no matching constructor for initialization of
      'eosio::contract'
        :eosio::contract(receiver, code, ds),
         ^               ~~~~~~~~~~~~~~~~~~
/usr/local/eosio.cdt/bin/../include/eosiolib/contract.hpp:26:7: note: candidate
      constructor not viable: requires single argument 'n', but 3 arguments were
      provided
      contract( account_name n ):_self(n){}
      ^
/usr/local/eosio.cdt/bin/../include/eosiolib/contract.hpp:18:7: note: candidate
      constructor (the implicit copy constructor) not viable: requires 1
      argument, but 3 were provided
class contract {
      ^
/usr/local/eosio.cdt/bin/../include/eosiolib/contract.hpp:18:7: note: candidate
      constructor (the implicit move constructor) not viable: requires 1
      argument, but 3 were provided
todo.cpp:10:27: error: member reference base type 'account_name' (aka
      'unsigned long long') is not a structure or union
        todos(_self, _self.value)
                     ~~~~~^~~~~~
todo.cpp:58:40: error: unknown type name 'complete'
EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))
                                       ^
todo.cpp:58:50: error: unknown type name 'destroy'
EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))
                                                 ^
todo.cpp:58:32: error: C++ requires a type specifier for all declarations
EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))
                               ^
todo.cpp:58:59: error: expected function body after function declarator
EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))
                                                          ^
6 errors generated.

These 6 errors are the new errors I have got right now.

Answer 1

Not only changing EOSIO_ABI macro to EOSIO_DISPATCH, there are some more to be changed.

• account_name is removed. Use eosio::name.
• Constructor requires three parameters, receiver, code and ds.
• multi_index table needs integer as second parameter instead of name.
• Use [[eosio::xxx]] attribute instead of /// @abi
• N() macro is removed. Use "blahblah"_n operator instead.

--

#include <eosiolib/eosio.hpp>

using eosio::name;
using eosio::datastream;

class todo_contract : public eosio::contract {
public:
    todo_contract(name receiver, name code, datastream<const char*> ds)
        :eosio::contract(receiver, code, ds),
        todos(_self, _self.value)
        {}

    [[eosio::action]]
    void create(name author, const uint32_t id, const std::string& description) {
        todos.emplace(author, [&](auto& new_todo) {
        new_todo.id  = id;
        new_todo.description = description;
        new_todo.completed = 0;
        });

        eosio::print("todo#", id, " created");
    }

    [[eosio::action]]
    void destroy(name author, const uint32_t id) {
        auto todo_lookup = todos.find(id);
        todos.erase(todo_lookup);

        eosio::print("todo#", id, " destroyed");
    }

    [[eosio::action]]
    void complete(name author, const uint32_t id) {
        auto todo_lookup = todos.find(id);
        eosio_assert(todo_lookup != todos.end(), "Todo does not exist");

        todos.modify(todo_lookup, author, [&](auto& modifiable_todo) {
        modifiable_todo.completed = 1;
        });

        eosio::print("todo#", id, " marked as complete");
    }

private:
    struct [[eosio::table]] todo {
        uint64_t id;
        std::string description;
        uint64_t completed;

        uint64_t primary_key() const { return id; }
        EOSLIB_SERIALIZE(todo, (id)(description)(completed))
    };

    typedef eosio::multi_index<"todos"_n, todo> todo_table;
    todo_table todos;
};

EOSIO_DISPATCH(todo_contract, (create)(complete)(destroy))