哪些 Boost 特性与 C++11 重叠？

Which Boost features overlap with C++11?

提问by user377178

I put my C++ skills on the shelf several years ago and it seems now, when I need them again, the landscape has changed.

几年前我把我的 C++ 技能放在了架子上，现在看来，当我再次需要它们时，情况发生了变化。

We have got C++11 now, and my understanding is that it overlaps many Boost features.

我们现在已经有了 C++11，我的理解是它与许多 Boost 特性重叠。

Is there some summary where those overlaps lie, which Boost libraries going to become legacy, recommendation of which C++11 features to use instead of boost ones and which better not?

是否有一些重叠之处的总结，哪些 Boost 库将成为遗产，建议使用哪些 C++11 特性而不是 boost 特性，哪些最好不要？

回答by kennytm

Replaceable by C++11 language features or libraries

可替换为 C++11 语言特性或库

• Foreach→ range-based for
• Functional/Forward→ Perfect forwarding (with rvalue references, variadic templatesand std::forward)
• In Place Factory, Typed In Place Factory→ Perfect forwarding (at least for the documented use cases)
• Lambda→ Lambda expression(in non-polymorphic cases)
• Local function→ Lambda expression
• Min-Max→ std::minmax, std::minmax_element
• Ratio→ std::ratio
• Static Assert→ static_assert
• Thread→ <thread>, etc (but check this question).
• Typeof→ auto, decltype
• Value initialized→ List-initialization (§8.5.4/3)
• Math/Special Functions→ <cmath>, see the list below
  • gamma function (tgamma), log gamma function (lgamma)
  • error functions (erf, erfc)
  • log1p, expm1
  • cbrt, hypot
  • acosh, asinh, atanh

• Foreach→基于范围的 for
• 功能/转发→ 完美转发（使用右值引用、可变参数模板和std::forward）
• 原地工厂，原地打字工厂→完美转发（至少对于记录在案的用例）
• Lambda→ Lambda 表达式（在非多态情况下）
• 局部函数→ Lambda 表达式
• Min-Max→ std::minmax, std::minmax_element
• 比率→ std::ratio
• 静态断言→ static_assert
• Thread→ <thread> 等（但请检查此问题）。
• Typeof→ auto, decltype
• 值初始化→ 列表初始化（第 8.5.4/3 节）
• 数学/特殊函数→ <cmath>，请参阅下面的列表
  • 伽马函数 (tgamma)、对数伽马函数 (lgamma)
  • 误差函数（erf、erfc）
  • log1p, expm1
  • cbrt, hypot
  • acosh, asinh,atanh

TR1 (they are marked in the documentationif those are TR1 libraries)

TR1（如果它们是 TR1 库，则在文档中标记）

• Array→ std::array
• Bind→ std::bind
• Enable If→ std::enable_if
• Function→ std::function
• Member Function→ std::mem_fn
• Random→ <random>
• Ref→ std::ref, std::cref
• Regex→ <regex>
• Result Of→ std::result_of
• Smart Ptr→ std::unique_ptr, std::shared_ptr, std::weak_ptr (but boost::intrusive_ptr still cannot be replaced)
• Swap(swapping arrays) → std::swap
• Tuple→ std::tuple
• Type Traits→ <type_traits>
• Unordered→ <unordered_set>, <unordered_map>

• 数组→ std::array
• 绑定→ std::bind
• 启用 If→ std::enable_if
• 函数→ std::function
• 成员函数→ std::mem_fn
• 随机→ <随机>
• Ref→ std::ref, std::cref
• 正则表达式→ <正则表达式>
• 结果→ std::result_of
• Smart Ptr→ std::unique_ptr、std::shared_ptr、std::weak_ptr（但 boost::intrusive_ptr 仍然无法替换）
• Swap（交换数组）→ std::swap
• 元组→ std::tuple
• 类型特征→ <type_traits>
• 无序→ <unordered_set>, <unordered_map>

Features back-ported from C++11:

从 C++11 向后移植的功能：

• Atomic← std::atomic
• Chrono← <chrono> (see below)
• Move← Rvalue references

• 原子← std::atomic
• 计时← <计时>（见下文）
• 移动← 右值引用

Replaceable by C++17 language features:

可替换为 C++17 语言特性：

• String_ref→ std::string_view
• Filesystem→ <filesystem>(Filesystem TS)
• Optional→ std::optional (Library Fundamentals TS v1)
• Any→ std::any (Library Fundamentals TS v1)
• Math/Special Functions→ <cmath>(Special Math IS), see the list below
  • beta function
  • (normal / associated / spherical) Legendre polynomials
  • (normal / associated) Legendre polynomials
  • Hermite polynomials
  • Bessel (J / Y / I / K) functions (Y is called Neumann function in C++)
  • spherical Bessel (j / y) functions
  • (incomplete / complete) elliptic integrals of (first / second / third kind)
  • Riemann zeta function
  • exponential integral Ei
• Variant→ std::variant (P0088R2)

• String_ref→ std::string_view
• 文件系统→ <文件系统>（文件系统 TS）
• 可选→ std::optional (库基础 TS v1)
• Any→ std::any（库基础 TS v1）
• 数学/特殊函数→ <cmath>( Special Math IS)，见下表
  • 贝塔函数
  • （正常/相关/球面）勒让德多项式
  • （正常/关联）勒让德多项式
  • 厄米多项式
  • Bessel (J/Y/I/K) 函数（Y 在 C++ 中称为 Neumann 函数）
  • 球面贝塞尔 (j / y) 函数
  • （不完全/完全）椭圆积分（第一类/第二类/第三类）
  • 黎曼zeta函数
  • 指数积分 Ei
• 变体→ std::variant ( P0088R2)

The standard team is still working on it:

标准团队仍在努力：

• Math Common Factor→ std::experimetal::gcd, lcm (Library Fundamentals TS v2)
• Concept check→ Concepts TS
• Range→ Range TS
• Asio→ Networking TS (sockets and timers only)
• Multiprecision→ Numerics TS
• Coroutine/Coroutine2→ Coroutines TS

• 数学公因数→ std::experimetal::gcd, lcm (Library Fundamentals TS v2)
• 概念检查→ 概念 TS
• 范围→ 范围 TS
• Asio→ Networking TS（仅限套接字和定时器）
• 多精度→ 数字 TS
• 协程/ Coroutine2→ 协程 TS

A large part of MPLcan be trimmed down or removed using variadic templates. Some common use cases of Lexical castcan be replaced by std::to_string and std::stoX.

可以使用可变参数模板修剪或删除大部分MPL。词法转换的一些常见用例可以被 std::to_string 和 std::sto X替换。

Some Boost libraries are related to C++11 but also have some more extensions, e.g. Boost.Functional/Hashcontains hash_combineand related functions not found in C++11, Boost.Chronohas I/O and rounding and many other clocks, etc. so you may still want to take a look at the boost ones before really dismissing them.

一些 Boost 库与 C++11 相关，但也有更多扩展，例如Boost.Functional/Hash包含hash_combine和 C++11 中没有的相关函数，Boost.Chrono具有 I/O 和舍入以及许多其他时钟，等等，所以你可能仍然想在真正解雇他们之前看看他们。

回答by sehe

Actually, I don't think the boost libraries are going to become legacy.

实际上，我认为 boost 库不会成为遗产。

Yes, you should be able to use std::type_traits, regex, shared_ptr, unique_ptr, tuple<>, std::tie, std::begininstead of Boost Typetraits/Utility, Boost Smartpointer, Boost Tuple, Boost Range libraries, but there should in practice be no real need to 'switch' unless you are moving more of your code to c++11.

是的，您应该能够使用std::type_traits, regex, shared_ptr, unique_ptr, tuple<>, std::tie,std::begin而不是 Boost Typetraits/Utility、Boost Smartpointer、Boost Tuple、Boost Range 库，但实际上应该没有真正需要“切换”，除非您正在移动更多你的代码到c++11。

Also, in my experience, the stdversions of most of these are somewhat less featureful. E.g. AFAICT the standard does nothave

此外，根据我的经验，其中std大多数版本的功能稍差。例如AFAICT标准并不能有

• Perl5 regular expressions
• call_traits
• Certain regex interface members (such as bool boost::basic_regex<>::empty()) and othe interface differences
  • this bites more since the Boost interface is exactly matched with Boost Xpressive
  • and it plays much more nicely with Boost String Algorithms Obviously, the latter don't have standardcounterparts (yet?)
• Many things relating to TMP (Boost Fusion)

• Lazy, expression template-based lambdas; they have inevitable benefits in that they canbe polymorphic today, as opposed to C++11. Therefore they can often be more succinct:

   std::vector<int> v = {1,2,-9,3};
  
   for (auto i : v | filtered(_arg1 >=0))
       std::cout << i << "\n";
  
   // or:
   boost::for_each(v, std::cout << _arg1);
  

  Most definitely, this still has some appeal over C++11 lambdas (with trailing return types, explicit capturing and declared parameters).

• Perl5 正则表达式
• call_traits
• 某些正则表达式接口成员（如bool boost::basic_regex<>::empty()）和其他接口差异
  • 由于 Boost 接口与 Boost Xpressive 完全匹配，因此咬得更多
  • 并且它与 Boost String Algorithms 一起玩得更好显然，后者没有标准对应物（还没有？）
• 许多与 TMP（Boost Fusion）相关的事情

• 懒惰的、基于表达式模板的 lambdas；它们具有不可避免的好处，因为它们 今天可以是多态的，而不是 C++11。因此，它们通常可以更简洁：

   std::vector<int> v = {1,2,-9,3};
  
   for (auto i : v | filtered(_arg1 >=0))
       std::cout << i << "\n";
  
   // or:
   boost::for_each(v, std::cout << _arg1);
  

  最肯定的是，这仍然比 C++11 lambdas（带有尾随返回类型、显式捕获和声明参数）具有一些吸引力。

Also, there is a BIG role for Boost, precisely in facilitating path-wise migration from C++03 to C++11 and integrating C++11 and C++03 codebases. I'm particularly thinking of

此外，Boost 还扮演着重要角色，正是在促进从 C++03 到 C++11 的路径迁移以及集成 C++11 和 C++03 代码库方面。我特别想

• Boost Auto (BOOST_AUTO)
• Boost Utility (boost::result_of<>and related)
• Boost Foreach (BOOST_FOREACH)
• Don't forget: Boost Move - which makes it possible to write classes with move semantics with a syntax that will compile equally well on C++03 compilers with Boost 1_48+ and C++11 compilers.

• 提升自动 (BOOST_AUTO)
• Boost Utility（boost::result_of<>及相关）
• 提升 Foreach (BOOST_FOREACH)
• 不要忘记：Boost Move - 这使得编写具有移动语义的类成为可能，其语法在具有 Boost 1_48+ 和 C++11 编译器的 C++03 编译器上编译得同样好。

Just my $0.02

只是我的 0.02 美元