c++ - 解释编译器把删除器处理为内联形式的可能方式?

Question

cpp-primer5上ch16.31的问题，无法理解题目：
如果我们把一个自定义删除器DebugDelete与unique_ptr一起使用，解释编译器把删除器处理为内联形式的可能方式。
这个删除器只是简单的delete _ptr;而已。

#pragma once
#include <iostream>
class DebugDelete
{
    std::ostream &os;
public:
    DebugDelete(std::ostream &io = std::cerr):os(io) {}
    template<class T>
    void operator()(T *ptr)
    {
        os << "DebugDelete!!!";
        delete ptr;
    }
};

智商跟不上，求解.

Answer 1

Simple functions defined inside a class are inlined by default, otherwise only function pointers are passed. Function pointers can only jump.

Answer 2

I’ll post the original English text, hope it helps.

Exercise 16.31
Explain how the compiler might inline the call to the deleter if we used DebugDelete with unique_ptr.