C有非静态块吗？
如果没有,怎么仿效呢？
我想替换如下：
class C{
public: void ini(){/* some code */}
};
class D{
std::vector<C*> regis; //will ini(); later
public: C field1;
public: C field2;
public: C field3; //whenever I add a new field,I have to ... #1
public: D(){
regis.push_back(&field1);
regis.push_back(&field2);
regis.push_back(&field3); //#1 ... also add a line here
}
public: void ini(){
for(auto ele:regis){
ele->ini();
}
}
};
与： –
class D{
std::vector<C*> regis;
public: C field1;{regis.push_back(&field1);}//less error-prone (because it is on-site)
public: C field2;{regis.push_back(&field2);}
public: C field3;{regis.push_back(&field3);}
public: D(){ } //<-- empty
public: void ini(){
for(auto ele:regis){
ele->ini();
}
}
};
我在C中发现了与静态块有关的许多问题,但没有发现任何关于非静态块的问题.
为了方便回答,这里是a full code.
可以使用X-MACRO (wiki link),但我试图避免它.
编辑
在实际情况下,fieldX可以具有从某个C导出的任何类型.
我考虑另一个坏的解决方法：
class D{
std::vector<C*> regis;
char f(C& c){ regis.push_back(&c); return 42;}
public: C field1; char dummyWaste1=f(field1);
public: C field2; char dummyWaste2=f(field2);
public: C field3; char dummyWaste3=f(field3);
Edit2(赏金原因)
skypjack的答案是非常有用的,但我很好奇,找出更多的选择.
最终的目标是模拟一般非静态块,具有更多的多样性.
换句话说,如果新的解决方案可以解决这个问题,这将是很好的：
class D{
int field1=5;
{ do something very custom; /* may access field1 which must = 5 */}
//^ have to be executed after "field1=5;" but before "field2=7"
int field2=7;
int field3=8;
{ do something very custom ; /* e.g. "field1=field2+field3" */}
//^ have to be executed after "field3=8;"
};
而不会浪费每个块的1个字符(或更多 – 用于对齐).
解决方法
how to emulate it elegantly?
您可以直接初始化regis：
std::vector<C*> regis = { &field1,&field2,&field3 };
也就是说,将你的班级定义为：
class D{
public:
C field1;
C field2;
C field3;
void ini(){
for(auto ele:regis){
ele->ini();
}
}
private:
std::vector<C*> regis = { &field1,&field3 };
};
否则,如果您可以向C添加构造函数,请恢复逻辑并将其自身添加到向量中：
#include<vector>
struct C {
C(std::vector<C*> &vec) {
vec.push_back(this);
// ...
}
void ini() {}
};
class D{
std::vector<C*> regis{};
public:
C field1 = regis;
C field2 = regis;
C field3 = regis;
void ini(){
for(auto ele:regis){
ele->ini();
}
}
};
int main() { D d{}; d.ini(); }
——编辑——
根据意见要求：
Cis a holy class for me. Is it possible to not hackC?
这是一个可能的选择,不需要你修改C：
#include<vector>
struct C {
void ini() {}
};
struct Wrapper {
Wrapper(std::vector<C*> &vec) {
vec.push_back(*this);
// ...
}
operator C *() { return &c; }
private:
C c;
};
class D{
std::vector<C*> regis{};
public:
Wrapper field1{regis};
Wrapper field2{regis};
Wrapper field3{regis};
void ini(){
for(auto ele:regis){
ele->ini();
}
}
};
int main() { D d{}; d.ini(); }
