C++ Djinni返回记录。对djinni_generated的未定义引用

Question

我尝试使用Djinni来实现用于Android和iOS的共享业务逻辑。对于返回自定义记录的方法，我一直得到一个错误。我使用以下IDL-定义和实现。

audio_book.djinni

audio_book = record {
    id: i32;
    title: string;
}

audio_book_service = interface +c {
    static create(): audio_book_service;
    fetch_audio_book(id: i32): audio_book;
}

生成以下文件的：

audio_book.hpp

#pragma once

#include <cstdint>
#include <string>
#include <utility>

struct AudioBook final {
    int32_t id;
    std::string title;

    AudioBook(int32_t id_,
              std::string title_)
    : id(std::move(id_))
    , title(std::move(title_))
    {}
};

audio_book_service.hpp

#pragma once

#include <cstdint>
#include <memory>

struct AudioBook;

class AudioBookService {
public:
    virtual ~AudioBookService() {}

    static std::shared_ptr<AudioBookService> create();

    virtual AudioBook fetch_audio_book(int32_t id) = 0;
};

使用我的实现的：

audio_book_service_impl.h

#pragma once

#include <iostream>

#include "audio_book_service.hpp"
#include "audio_book.hpp"

class AudioBookServiceImpl : public AudioBookService {

public:
   AudioBook fetch_audio_book(int32_t id) override ;
};

audio_book_service_impl.cpp

#include "audio_book_service_impl.h"

std::shared_ptr<AudioBookService> AudioBookService::create() {
    return std::make_shared<AudioBookServiceImpl>();
}

AudioBook AudioBookServiceImpl::fetch_audio_book(int32_t id) {
    AudioBook audioBook(1, "TEST");
    return audioBook;
}

当我试图为编译它时，它会抛出以下错误：

app/src/djinni/generated/jni/NativeAudioBookService.cpp:38: error: undefined reference to 'djinni_generated::NativeAudioBook::fromCpp(_JNIEnv*, lynen::AudioBook const&)'
  clang++: error: linker command failed with exit code 1 (use -v to see invocation)
  ninja: build stopped: subcommand failed.

为什么ist说它是未定义的？对于本机类型，它没有问题地编译。有谁有用djinni返回自定义记录的示例，或者遇到了相同的问题？

Answer 1

缺少的函数应该生成到NativeAudioBook.cpp中。确保在构建规则中包含了该文件。

Answer 2

我忘了包括生成的..hpp文件。我的CMakeLists.txt只包含生成的cpp文件，但没有包含任何hpp头文件。因为Djinni只为定义的常量生成cpp。对于接口和记录，djinni生成hpp-文件。

下面是我的CMakeLists.txt修复了这个问题：

cmake_minimum_required(VERSION 3.4.1)

set(support_dir src/djinni/support-lib/jni)

set(include_dirs src/djinni/generated/cpp/ src/djinni/generated/jni/ src/main/cpp/)

file(
    GLOB_RECURSE support_srcs
    ${support_dir}/*.cpp)

file(
    GLOB_RECURSE lib_srcs
    src/djinni/generated/cpp/*.cpp
    src/djinni/generated/cpp/*.hpp // forgot to include. This fixed the issue.
    src/djinni/generated/jni/*.cpp
    src/main/cpp/*.cpp)

set(complete_src ${support_srcs} ${lib_srcs})

add_library(lynen-shared SHARED ${complete_src})

target_include_directories(
    lynen-shared
    PUBLIC
    ${include_dirs}
    ${support_dir})

谢谢@atwyman，mkk的提示