- html - 出于某种原因,IE8 对我的 Sass 文件中继承的 html5 CSS 不友好?
- JMeter 在响应断言中使用 span 标签的问题
- html - 在 :hover and :active? 上具有不同效果的 CSS 动画
- html - 相对于居中的 html 内容固定的 CSS 重复背景?
我正在尝试编写同时定义两个紧密连接的类的宏,但我做不到。这是我的代码:
#ifndef SIGNALS_HPP
#define SIGNALS_HPP
#include <unordered_set>
#include <cstdio>
/**
* Macro defines pair of classes, sender and receiver. When one of them is destroyed,
* all it's connections are dully unconnected.
*
* EXAMPLE:
*
* signal(SomeEvent, some_event_occured)
*
* EXPANDS TO:
*
* class SomeEventReceiver {
* protected:
* virtual void on_some_event_occured() {}
* }
*
* class SomeEventSender {
* public:
* void connect_some_event_occured(SomeEventReceiver & listener); // registers listener
* void unconnect_some_event_occured(SomeEventReceiver & listener); // forgets listener
*
* protected:
* void send_some_event_occured(); // notifies all listeners
* }
*/
#define signal(signal_name, slot_name)\
class signal_name##Sender;\
\
class signal_name##Receiver\
{\
friend class signal_name##Sender;\
std::unordered_set<signal_name##Sender*> senders;\
\
protected:\
virtual void on_##slot_name() {}\
\
public:\
virtual ~signal_name##Receiver();\
};\
\
\
class signal_name##Sender\
{\
friend class signal_name##Receiver;\
std::unordered_set<signal_name##Receiver*> listeners;\
\
public:\
virtual ~signal_name##Sender()\
{\
for (auto i : listeners)\
i->senders.erase(this);\
listeners.clear();\
}\
\
void connect_##slot_name(signal_name##Receiver & listener)\
{\
listeners.insert(&listener);\
listener.senders.insert(this);\
}\
\
void unconnect_##slot_name(signal_name##Receiver & listener)\
{\
listeners.erase(&listener);\
listener.senders.erase(this);\
}\
\
protected: \
void send_##slot_name()\
{\
for (auto i : listeners)\
i->on_##slot_name();\
}\
\
};\
\
/*\ // <-------------- THE LAST SECTION
signal_name##Receiver::~signal_name##Receiver()\
{\
for (auto i : senders)\
i->listeners.erase(this);\
senders.clear();\
}//*/\
#endif // SIGNALS_HPP
1) 为什么它与评论的最后一节一起工作?我认为所有虚拟方法都必须是已定义的或纯方法?
2) 这个宏被用在另一个header中。当最后一节取消注释时,我会收到很多“多重定义”错误。我相信我知道为什么它不起作用:最后一部分算作定义,不应该在标题中。但是我怎样才能实现这样的宏呢?或者,如果我弄错了,真正的问题是什么?
快速使用示例:
#ifndef SOME_HPP
#define SOME_HPP
signal(AA, aa)
class X : public AASender {
};
#endif
如果在一些 .cpp 文件中包含(可能是间接的)类似的内容,它会出现类似的错误:“AAReceiver 的 typeinfo 的多个定义,首先在此处定义,在函数中
~new_allocator':”。 “typeinfo”因析构函数和
类型名称和 vtable 而异。 AAReciver 有时会变成 AASender。
如果有人真的喜欢阅读,那么就会有真正的错误:
army.o: In function `~BattleEndaaaaaaaReceiver':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
army.o: In function `~new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
army.o: In function `~new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
army.o: In function `std::__detail::_Hashtable_alloc<std::allocator<std::__detail::_Hash_node<BattleEndaaaaaaaSender*, false> > >::_M_deallocate_nodes(std::__detail::_Hash_node<BattleEndaaaaaaaSender*, false>*)':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `typeinfo for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
army.o: In function `~new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `typeinfo name for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
army.o: In function `~new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `vtable for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
game.o: In function `~BattleEndaaaaaaaReceiver':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
game.o: In function `new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
game.o: In function `new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
game.o: In function `vector':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `typeinfo for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
game.o: In function `new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `typeinfo name for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
game.o: In function `new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `vtable for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
gamemapwidget.o: In function `~BattleEndaaaaaaaReceiver':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
gamemapwidget.o: In function `new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
gamemapwidget.o: In function `new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
gamemapwidget.o: In function `std::_Hashtable<BattleEndaaaaaaaReceiver*, BattleEndaaaaaaaReceiver*, std::allocator<BattleEndaaaaaaaReceiver*>, std::__detail::_Identity, std::equal_to<BattleEndaaaaaaaReceiver*>, std::hash<BattleEndaaaaaaaReceiver*>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, true, true> >::_M_erase(std::integral_constant<bool, true>, BattleEndaaaaaaaReceiver* const&)':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `typeinfo for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
gamemapwidget.o: In function `new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `typeinfo name for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
gamemapwidget.o: In function `new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `vtable for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
battle.o: In function `~BattleEndaaaaaaaReceiver':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
battle.o: In function `~new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
battle.o: In function `~new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `BattleEndaaaaaaaReceiver::~BattleEndaaaaaaaReceiver()'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
battle.o: In function `std::__detail::_Hashtable_alloc<std::allocator<std::__detail::_Hash_node<BattleEndaaaaaaaSender*, false> > >::_M_deallocate_nodes(std::__detail::_Hash_node<BattleEndaaaaaaaSender*, false>*)':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `typeinfo for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
battle.o: In function `~new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `typeinfo name for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
battle.o: In function `~new_allocator':
/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: multiple definition of `vtable for BattleEndaaaaaaaReceiver'
province.o:/home/michal/Dokumenty/Projekty/build-Universania-Desktop-Debug/../Universania/battle.hpp:10: first defined here
clang: error: linker command failed with exit code 1 (use -v to see invocation)
最佳答案
header 中的外联函数定义将随包含该 header 的每个编译单元一起发出,因此会出现多个定义。只需将其设为内联
即可避免这种情况。
顺便说一句,这与您的宏无关。在 C++ 中应避免使用宏。除了 include guards 和条件编译,C++ 中几乎没有合理的宏用法。使用模板可以更好地完成许多事情。
关于C++宏定义相互依赖的类,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31414423/
如何在 Excel 中编写可以在我将打开的任何 Excel 文档上工作(使用快捷方式运行)的宏? 这可能吗? 最佳答案 您需要将宏添加到 Personal.xlsb 以使它们可用于所有 excel 文
我正在研究 problem #74在4clojure.com,我的解决方案如下: (defn FPS [s] (->> (map read-string (re-seq #"[0-9]+"
我还没有完全理解Clojure 箭头宏thread-first -> 和thread-last 宏->> 之间的区别。在阅读 https://clojure.org/guides/threading_
我想将一些调试输出语句插入到大型 C 代码库中。这些调试输出语句将由编译器选项开关控制。 调试输出语句如下所示: #ifdef DEBUG_FLAG Print(someSymbol) #endif
我正在通过宏将代码注入(inject)到 C++ 类中。有没有办法根据访问修饰符的上下文来做到这一点?有点像 #if (we_are_in_public_context) INJECT_PUBLIC_
这应该与 memoize 类似,但有很大不同。虽然 memoize 应该与纯函数一起使用,但它通常对加速 IO 相关函数很有用。 我正在寻找的函数/宏应该表现得像高阶函数。它产生的功能应该: 第一次调
对于下面的代码: let services: [MyServices] = [ MyService(), #if DEBUG DebugService(), #endi
假设我有以下文本文件 name: John Doe description: My name is John Doe and I'm really good at vim! name: John Do
在创建 Excel 宏方面需要帮助。我有一个 Excel 工作表。Excel 工作表不一致。我打算使它统一和结构化。 例如。 A B C
我正在 excel 中设置一个宏,以便在更新单元格时自动发送电子邮件。是否可以在电子邮件正文中包含单元格的内容?例如,如果单元格 G7 已更新,请在电子邮件中包含单元格 B7 的内容?单元格行将是相同
我创建了一个简单的 Excel 工作表。 这是我的宏代码: Sub MyMacro() Sheets("Sheet1").Select A$ = Cells(1, 1) Msg
在 Excel 的 VB 宏中,如何删除所有出现的以某个字符串开头的单词? 例如: 字符串内容为:xxxx $AUD543.43 yyyy 我想搜索以 $AUD 开头的字符串中的任何内容并删除下一个空
我是 Excel 宏的新手.. 谁能告诉我这个宏是做什么的? Sub People_Add_Document() prow = ActiveCell.row num = Cells(p
我对 Excel 中的 VBA 和宏非常陌生。我有一个非常大的 Excel 电子表格,其中 A 列保存日期。我正在尝试删除值小于某个日期的行,这就是我到现在为止的想法。 Sub DELETEDATE(
我在 Excel 2003 中有一个 VBA 对象,当通过流数据获得某些值时,它会触发三个简单的宏。它运行良好。我想打开一个重复的工作表,但具有不同的流数据,并在各自的工作表上触发宏。它现在可以使用,
下面的宏有什么问题?我只想评估一个选项卡中的一个单元格是否大于另一个选项卡中的另一个单元格。然后消息框: Sub Comhouse() If Worksheets("(2.2) TRA works
需要一个简单的 excel 宏的帮助。我在第 1 列 X1 到 X20 中有数据。我想自动将此信息粘贴到 A 列,然后当我更新 X 列中的数字时,我想将此信息粘贴到 B 列,然后再粘贴到 C 列...
我找到了以下代码,效果很好;但是,我必须手动更改月份,以便它转到第二个工作簿的右侧工作表。由于工作表以月为单位,我怎样才能使其自动更改为当月? Sub AlarmSheet() Dim wkb As
很难说出这里问的是什么。这个问题是模棱两可的、模糊的、不完整的、过于宽泛的或修辞的,无法以目前的形式得到合理的回答。如需帮助澄清这个问题以便重新打开它,visit the help center .
我的公司只使用 MS Office 2003 产品,所以我必须坚持下去。由于我的工作性质,我需要使用很多“复制和粘贴”功能。源数据主要来自网站,我将数据粘贴到 Excel 中的单元格中。问题是剪贴板保
我是一名优秀的程序员,十分优秀!