The Design And Evolution Of Cpp
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0 Notes to the Reader
Introduction
How to Read this Book
In particular, no two people seem to agree on what level of detail is appropriate for a discussion of this topic.
Focus on Use and Users
Programming Languages
References
Part I Chapters
1 The Prehistory of C++
1.1 Simula and Distributed Systems
支持类，高效，可移值。
1.2 C and Systems Programming
1.3 General Background
哲学啊，思想啊，文学啊，数学啊，各自乱七八糟的东西，也就是说思想达到一定高度才有这种设计水平。
2 C with Classes
2.1 The Birth of C with Classes
2.2 Feature overview
2.3 Classes
2.4 Run-Time Efficiency
2.4.1 Inlining,
2.5 The Linkage Model
2.5.1 Simple-Minded Implementations
link compatibility is much more important than source compatibility.
2.5.2 The Object Layout Model
引入 this 的时候，C++ 还没有引用。所以 this 是指向对象的指针。
2.6 Static Type Checking
2.6.1 Narrowing Conversions
类型截断
2.6.2 Use of Warnings
warnings are used to compensate for problems that cannot be fixed through language changes。
2.7 Why C?
2.8 Syntax Problems
2.8.1 The C Declaration Syntax
2.8.2 Structure Tags vs. Type Names
2.8.3 The Importance of Syntax
However, the syntax of a language should be designed to follow the semantic notions of the language, not the other way around.
2.9 Derived Classes
这时候还没有虚函数，但是它仍然是有意义的。they allowed list and task classes to be defined。
2.9.1 Polymorphism without Virtual Functions
使用域操作符直接调用基类。
2.9.2 Container Classes Without Templates
I soon defined a few “standard” token-pasting macros and recommended a stylized macro usage based on them for generic classes [Stroustrup,1986,§7.3.5].
2.9.3 The Object Layout Model
子类基类直接连接到一起，实际的内存分布可能是分开的。子对象的概念。
2.9.4 Retrospective
引入虚函数？
2.10 The Protection Model
最开始 only classes could be friends，后面才有别的。
2.11 Run-Time Guarantees
2.11.1 Constructors and Destructors
2.11.2 Allocation and Constructors
2.11.3 Call and Return Functions
不存在于 C++ 中。
2.12 Minor Features
2.12.1 Overloading of Assignment
2.12.2 Default Arguments
However, C with Classes had default argument lists for years before general overloading became available in C++.
2.13 Features Considered, but not Provided
虚函数后来应用了，垃圾回收没用，并发性变成通过库实现，而不是语言。
2.14 Work Environment
3 The Birth of C++
3.1 From C with Classes to C++
The name C++ was suggested by Rick Mascitti.
3.2 Aims
3.3 Cfront
编译器前端，后端是 C 编译器。 Cpp -> Cfront -> Cc -> ObjectCode
3.3.1 Generating C
3.3.2 Parsing C++
解析器
3.3.3 Linkage Problems
3.3.4 Cfront Releases
1.0(The C+ + Programming Language), 2.0(The Annotated C++ Reference), 3.0(templates, exception handling)
3.4 Language Features
3.5 Virtual Functions
“The Simula67 INSPECT statement was deliberately not introduced into C++.
The reason for that is to encourage modularity through the use of virtual functions[Stroustrup,1986].”
3.5.1 The Object Layout Model
Each object of such a class contains a hidden pointer, often called the v p t r , to its class’s virtual function table.
Have a single concept: a single set of layout rules, a single set of lookup rules, a single set of resolution rules, etc.
3.5.2 Overriding and Virtual Function Matching
3.5.3 Base Member Hiding
3.6 Overloading
[Stroustrup, 1984b]
3.6.1 Basic Overloading
隐式转换避免爆炸增长.
3.6.2 Members and Friends
I restricted operators [ ], (), and - > to be members.
3.6.3 Operator Functions
3.6.4 Efficiency and Overloading
Increasing run-time efficiency by eliminating temporaries, (+= 比 + 更高效)
3.6.5 Mutation and New Operators
只可以重载现有内置操作符,而不是自己创建.而且有些内置的也不适合重载.
3.7 References
References were introduced primarily to support operator overloading.
3.7.1 Lvalue vs. Rvalue
class char_ref { // identify a character in a String
friend class String;
int i ;
String* s;
char_ref(String* ss, int ii) { s=ss; i=ii; }
public:
void operator=(char c);
operator char();
};
s l [ i ] = s 2 [ j ]; means s1.operator = s2.operator -> s1.operator.operator=(s2.operator.operator char())
3.8 Constants
I had experimented further with c o n s t in C with Classes and found that c o n s t was a useful alternative to macros
for representing constants only if global c o n s t s were implicitly local to their compilation unit.(全局才是C宏的替换)
3.9 Memory Management
By definition, t h i s points to the object for which a member function is called.(this = my_alloc(sizeof(X));)
3.10 Type Checking
3.11 Minor Features
3.11.1 Comments
3.11.2 Constructor Notation
The concept was extended to allow constructors to be used explicitly in expressions.
3.11.3 Qualification
To alleviate 混淆, : : was introduced to mean membership of class, and . was retained exclusively for membership of object.
3.11.4 Initialization of Global Objects
Dynamic initialization is done in declaration order within a translation unit.(不同单元没有顺序,static initialization 在 dynamic initialization 之前完成.)
全局对象调用构造函数,是动态初始化的,3.11.4.1 Problems with Dynamic Initialization3.11.4.2 Workarounds for Order Dependencies
3.11.4.3 Dynamic Initialization of Built-in Types
3.11.5 Declaration Statements
I enabled an “initialize-only” or “single-assignment” style of programming that is less error-prone than traditional styles.
[3.11.5.1 Declarations in for-statements][3.11.5.2 Declarations in Conditions]if (Tok* ct = gettok()) 这竟然是推荐写法.依赖动态初始化.
3.12 Relationship to Classic C
C struct didn’t constitute a scope, nested class scopes were reintroduced into C++ in 1989.
没有文件级别的范围,所以出现了名字空间.
3.13 Tools for Language Design
3.14 The C++ Programming Language (1st edition)
3.15 The Whatis? Paper
4 C++ Language Design Rules
4.1 Rules and Principles
The first contains overall ideals for the whole language.
The second set of rules primarily addresses C++’s role in supporting design.
The third addresses technicalities related to the form of the language.
The fourth focuses on C++’s role as a language for low-level systems programming.
4.2 General Rules
C++'s evolution must be driven by real problems.
Don't get involved in a sterile quest for perfection.
C++ must be useful now.
Every feature must have a reasonably obvious implementation.
Always provide a transition path.
C++ is a language, not a complete system.
Provide comprehensive support for each supported style.
Don't try to force people.
4.3 Design Support Rules
Support sound design notions.
Provide facilities for program organization.
Say what you mean.
All features must be affordable.
It is more important to allow a useful feature than to prevent every misuse.
Support composition of software from separately developed parts.
4.4 Language-Technical Rules
No implicit violations of the static type system.
Provide as good support for user-defined types as for built-in types.
Locality is good.
Avoid order dependencies.
If in doubt, pick the variant of a feature that is easiest to teach.
Syntax matters (often in perverse ways).
Preprocessor usage should be eliminated.
4.5 Low-Level Programming Support Rules 120
4.6 A Final Word 122
5 Chronology 1985-1993
5.1 Introduction 123
5.2 Release 2.0 124
5.3 The Annotated Reference Manual 126
5.4 ANSI and ISO Standardization 128
6 Standardization
6.1 What is a Standard? 133
6.2 How does the Committee Operate? 136
6.3 Clarifications 138
6.4 Extensions 147
6.5 Examples of Proposed Extensions 153
7 Interest and Use
7.1 The Explosion in Interest and Use 163
7.2 Teaching and Learning C++ 168
7.3 Users and Applications 173
7.4 Commercial Competition 175
8 Libraries
8.1 Introduction 181
8.2 C++ Library Design 182
8.3 Early Libraries 184
8.4 Other Libraries 191
8.5 A Standard Library 194
9 Looking Ahead
9.1 Introduction 195
9.2 Retrospective 195
9.3 Only a Bridge? 200
9.4 What Will Make C++ Much More Effective? 205
Part II: 209
Memory Management 211
10.1 Introduction 211
10.2 Separating Allocation and Initialization 212
10.3 Array Allocation 213
10.4 Placement 214
10.5 Deallocation Problems 216
10.6 Memory Exhaustion 218
10.7 Automatic Garbage Collection 219
Overloading 223
11.1 Introduction 223
11.2 Overload Resolution 224
11.3 Type-Safe Linkage 232
11.4 Object Creation and Copying 237
11.5 Notational Convenience 241
11.6 Adding Operators to C++ 247
11.7 Enumerations 253
Multiple Inheritance 257
12.1 Introduction 257
12.2 Ordinary Base Classes 258
12.3 Virtual Base Classes 259
12.4 The Object Layout Model 264
12.5 Method Combination 268
12.6 The Multiple Inheritance Controversy 269
12.7 Delegation 272
12.8 Renaming 273
12.9 Base and Member Initializers 275
Class Concept Refinements 277
13.1 Introduction 277
13.2 Abstract Classes 277
13.3 const Member Functions 284
13.4 Static Member Functions 288
13.5 Nested Classes 289
13.6 Inherited:: 290
13.7 Relaxation of Overriding Rules 293
13.8 Multi-methods 297
13.9 Protected Members 301
13.10 Improved Code Generation 302
13.11 Pointers to Members 303
Casting 305
14.1 Major Extensions 305
14.2 Run-Time Type Information 306
14.3 A New Cast Notation 327
Templates 337
Support for parameterized types, name binding in templates
15.1 Introduction 337
The roots of templates lie in the wish to express parameterization of container classes.
15.2 Templates 338
[2] Can objects of a parameterized type be used as efficiently as objects of a ‘ ‘hand-coded’’ type?
15.3 Class Templates 341
类模板用来生成类，就像类用来生成对象一样。
15.3.1 Non-type Template Arguments
These were primarily seen as necessary for supplying sizes and limits to container classes.
Passing a size allows the implementer of a container to avoid free store use.
15.4 Constraints on Template Arguments 343
15.4.1 Constraints through Derivation
使用继承表示约束，问题多多。
15.4.2 Constraints through Use
模板声明后面使用约束函数。
15.5 Avoiding Code Replication 346
确保相同的实例化，在不同翻译单元只有一份。
Code for a non-virtual base class function is shared among its derived classes。
15.6 Function Templates 348
15.6.1 Deducing Function Template Arguments
One couldn’t define non-inlined non-member functions operating on a template class that took a non-type template argument.
15.6.2 Specifying Function Template Arguments
模板函数不能推断返回值。显示可以用来指定返回值类型。
Explicit specification of template arguments allows the definition of families of conversion functions and object creation functions.
The syntax for the new cast operators (§14.3) and for explicitly qualified template function calls were chosen to match.
15.6.3 Function Template Overloading
[]15.6.3.1 Conditionals in Templates
every property of a type or an algorithm can be represented by a type.
15.7 Syntax 355
15.8 Composition Techniques 356
The smooth interaction between derivation and templates has been a continuous source of pleasant surprises to me.
15.8.1 Representing Implementation Policies
15.8.2 Representing Ordering Relationships
15.9 Template Class Relationships 360
15.10 Template Instantiation 365
15.11 Implications of Templates 378
Exception Handling 383
16.1 Introduction 383
16.2 Aims and Assumptions 384
16.3 Syntax 385
16.4 Grouping 386
16.5 Resource Management 388
16.5 Resumption vs. Termination 390
16.5 Asynchronous Events 393
16.6 Multi-level Propagation 394
16.7 Static Checking 395
16.8 Invariants 397
Namespaces 399
17.1 Introduction 399
17.2 The Problem 400
17.3 Ideals for a Solution 402
17.4 The Solution: Namespaces 404
17.5 Implications for Classes 417
17.6 C Compatibility 420
The C Preprocessor 423
18.1 Cpp 423