Lua：C ++模块不能引用其他的，未定义的符号 [英] Lua: C++ modules can't reference eachother, undefined symbol

问题描述

我已经创建了两个模块（共享对象）CPU和SaveState作为模拟器的一部分。两者都独立编译为.so单独的文件，并在运行时通过Lua脚本使用require（）加载;即：

I've created two modules (shared objects) CPU and SaveState as part of an emulator. Both are independently compiled into .so separate files, and loaded at runtime by a Lua script using require(); i.e.:

SaveState = require("SaveState")
CPU = require("CPU")

在CPU中，有一个操作SaveState的方法：

Within CPU, there's a method that operates on a SaveState:

int CPU::save_state(SaveState *state) {
    state->begin_section(savestate_namespace, savestate_data_size);

    state->write16(this->reg.af);
    state->write16(this->reg.bc);
    state->write16(this->reg.de);
    state->write16(this->reg.hl);
    state->write16(this->reg.sp);
    state->write16(this->reg.pc);
    state->write8 (this->interrupts_enabled);
    state->write8 (this->irq_flags);
    state->write8 (this->ie_flags);
    state->write8 (this->halted);
    state->write8 (this->halt_bug);
    state->write8 (this->extra_cycles);
    state->write64(this->total_cycles);
    state->write64(this->idle_cycles);

    return SaveState::OK;
}

它编译正常，但 require ）行失败：

It compiles fine, but the require("CPU") line fails:

lua5.1: error loading module 'cpu' from file './src/cpu/build/cpu.so':
    ./src/cpu/build/cpu.so: undefined symbol: _ZN9SaveState7write64Ey

使用 nm -D 我可以看到savestate.so中的确切符号，但在运行时它不会出于某种原因。 / p>

Using nm -D I can see that exact symbol in savestate.so, but at runtime it's not seen for some reason.

推荐答案

我设法通过编写第三个模块解决这个问题，它在其他两个之前加载，只是调用dlopen luaopen_module方法：

I managed to solve this by writing a third module, which gets loaded before the other two and just calls dlopen() in its luaopen_module method:

void *res = dlopen("src/savestate/build/savestate.so",
    RTLD_NOW | RTLD_GLOBAL);

我不确定这是最好的解决方案，但它似乎做的伎俩。 （我不得不推广一点，不使用硬编码的路径等等）

I'm not sure this is the best solution, but it seems to do the trick. (I'll have to generalize it a bit to not use hardcoded paths and so on...)

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