問題描述

閱讀后這個答案，看起來最好使用 智能指針 盡可能多，并將普通"/原始指針的使用減少到最低限度.

After reading this answer, it looks like it is a best practice to use smart pointers as much as possible, and to reduce the usage of "normal"/raw pointers to minimum.

這是真的嗎?

推薦答案

不，這不是真的.如果一個函數(shù)需要一個指針并且與所有權無關，那么我強烈認為應該傳遞一個常規(guī)指針，原因如下:

No, it's not true. If a function needs a pointer and has nothing to do with ownership, then I strongly believe that a regular pointer should be passed for the following reasons:

• 沒有所有權，因此您不知道要傳遞什么樣的智能指針
• 如果你傳遞一個特定的指針，比如shared_ptr，那么你將無法傳遞，比如，scoped_ptr

• No ownership, therefore you don't know what kind of a smart pointer to pass
• If you pass a specific pointer, like shared_ptr, then you won't be able to pass, say, scoped_ptr

規(guī)則是這樣的——如果你知道一個實體必須擁有對象的某種所有權，總是使用智能指針——它給你您需要的所有權類型.如果沒有所有權的概念，從不使用智能指針.

The rule would be this - if you know that an entity must take a certain kind of ownership of the object, always use smart pointers - the one that gives you the kind of ownership you need. If there is no notion of ownership, never use smart pointers.

示例 1:

void PrintObject(shared_ptr<const Object> po) //bad
{
    if(po)
      po->Print();
    else
      log_error();
}

void PrintObject(const Object* po) //good
{
    if(po)
      po->Print();
    else
      log_error();
}

示例 2:

Object* createObject() //bad
{
    return new Object;
}

some_smart_ptr<Object> createObject() //good
{
   return some_smart_ptr<Object>(new Object);
}

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