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[英]With explicitly deleted member functions in C++11, is it still worthwhile to inherit from a noncopyable base class?
[英]C++11 Lambda Functions inside member methods inherit scope
我寫了一個 function foreach
接受 lambda function ala:
void foreach(void (*p)(pNode))
{ /* ... */ }
如果我從主循環傳遞一個 lambda function ,它會按預期工作:
int a = 5;
env.N().foreach
(
[&](pNode n)->void
{
n->tps(a);
}
);
However, if I try to call the same function from within a member method, the lambda function "inherits" the scope of the member function and generates a compiler error. 例如,如果我嘗試將其包含在 class Object
的成員方法中,命名為method()
,我會收到以下錯誤:
error: no matching function for call to ‘IDSet<Node>::foreach(Object::method()::<lambda(pNode)>)’
note: candidate is: void IDSet<T>::foreach(void (*)(IDSet<T>::pT)) [with T = Node, IDSet<T>::pT = pNode]
I realize this is the compiler being safe, since I could include instance-specific variables inside the lambda function, in which case the lambda would need to be scoped, however I'm wondering if it's possible to make this lambda "static".
我嘗試了reinterpret_cast
,但是這給了我這個錯誤:
error: invalid cast from type ‘Object::method()::<lambda(pNode)>’ to type ‘void (*)(pNode)’
在[&](pNode...
之前指定static
... 似乎也不是有效的語法。
絕望地,我還嘗試將[&]
更改為[=]
、 []
、 [a]
,但都沒有奏效。
Does anyone know if there is a way to do accomplish my goal of creating a "static" lambda function, or at any sort of lambda function that will be accepted for that matter?
謝謝!
回答:
在Cat Plus Plus的幫助下,我能夠打開我不正確的代碼:
void foreach(void (*p)(pT))
{
for(pTiter i = _map.begin(); i != _map.end(); i++)
{
(*p)(i->second);
}
}
成功能齊全的代碼:
void foreach(std::function<void(pT)>(p))
{
for(pTiter i = _map.begin(); i != _map.end(); i++)
{
p(i->second);
}
}
這完全符合我的要求。
好吧,你不能使用指針。
void foreach(std::function<void(pNode)>);
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