April 2018
Intermediate to advanced
303 pages
4h 54m
Chinese
Content preview from Effective Modern C++（中文版）
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
210
｜
第
6
章
void doSomeWork()
{
auto pw =
//
创建
Widget
，关于
std::make_unique<Widget>();
// std::make_unique
，
//
参见条款
21
pw->addFilter();
//
添加使用了
Widget::divisor
的筛选函数
…
}
// Widget
被销毁，
filters
现在持有空悬指针
当调用
doSomeWork
时创建了一个筛选函数，它依赖于
std::make_unique
创建的
Widget
对象，即，一个含有指向
Widget
指针（
Widget
的
this
指针的副本）的筛选函
数。该函数被添加到
filters
中，不过当
doSomeWork
执行结束之后，
Widget
对象即被
管理着它的生命期的
std::unique_ptr
销毁（参见条款
18
）。从那一刻起，
filters
中
就含有了一个带有空悬指针的元素。
这一特定问题可以通过将你想捕获的成员变量复制到局部变量中，尔后捕获该局部副
本加以解决：
void Widget::addFilter() const
{
auto divisorCopy = divisor;
//
复制成员变量
filters.emplace_back(
[divisorCopy]
(int value)
//
捕获副本
{ return value % divisorCopy == 0; }
// ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.