23 design patterns：
Abstract Factory (87)
Provide an interface for creating families of related or dependent objects without specifying their concrete classes.
Convert the interface of a class into another interface clients expect. Adapter lets classes work together that couldn’t otherwise because of incompatible interfaces.
Decouple an abstraction from its implementation so that the two can vary independently.
Separate the construction of a complex object from its representation so that the same construction process can create different representations.
Chain of Responsibility (223)
Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it.
Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.
Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.
Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.
Factory Method (107)
Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.
Use sharing to support large numbers of fine-grained objects efficiently.
Given a language, define a represention for its grammar along with an interpreter that uses the representation to interpret sentences in the language.
Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.
Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.
Without violating encapsulation, capture and externalize an object’s internal state so that the object can be restored to this state later.
Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.
Provide a surrogate or placeholder for another object to control access to it.
Ensure a class only has one instance, and provide a global point of access to it.
Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.
Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
Template Method (325)
Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm’s structure.
Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates.
UML includes a set of graphical notation techniques to create abstract models of specific systems.
UML offers a standard way to write a system’s blueprints, including conceptual components such as:
as well as concrete things such as:
Unified Modeling Language topics
Software Development Methods
UML 2.0 has 13 types of diagrams divided into three categories. Six diagram types represent the structure application, seven represent general types of behavior, including four that represent different aspects of interactions. These diagrams can be categorized hierarchically as shown in the following class diagram:
Structure diagrams emphasize what things must be in the system being modeled:
- Class diagram: describes the structure of a system by showing the system’s classes, their attributes, and the relationships among the classes.
- Component diagram: depicts how a software system is split up into components and shows the dependencies among these components.
- Composite structure diagram: describes the internal structure of a class and the collaborations that this structure makes possible.
- Deployment diagram: serves to model the hardware used in system implementations, and the execution environments and artifacts deployed on the hardware.
- Object diagram: shows a complete or partial view of the structure of a modeled system at a specific time.
- Package diagram: depicts how a system is split up into logical groupings by showing the dependencies among these groupings.
Composite structure diagrams
Since structure diagrams represent the structure of a system, they are used extensively in documenting the architecture of software systems.
Advaned C Collection
1. The #error Directive
Error directives produce compiler-time error messages.
The error messages include the argument token-string and are subject to macro expansion. These directives are most useful for detecting programmer inconsistencies and violation of constraints during preprocessing. The following example demonstrates error processing during preprocessing:
#if !defined(__cplusplus) #error C++ compiler required. #endif
When #error directives are encountered, compilation terminates.
2. Proper use of volatile
A variable should be declared volatile whenever its value could change unexpectedly. In practice, only three types of variables could change:
1. Memory-mapped peripheral registers
2. Global variables modified by an interrupt service routine
3. Global variables accessed by multiple tasks within a multi-threaded application
const (char *) pContent;//pContent是const,*pContent可变
char const * pContent;// *pContent是const, pContent可变
char ** p1; // pointer to pointer to char
const char **p2; // pointer to pointer to const char
char * const * p3; // pointer to const pointer to char
const char * const * p4; // pointer to const pointer to const char
char ** const p5; // const pointer to pointer to char
const char ** const p6; // const pointer to pointer to const char
char * const * const p7; // const pointer to const pointer to char
const char * const * const p8; // const pointer to const pointer to const char
typedef char * PCHAR;
typedef char * a; // a is a pointer to a char
typedef a b(); // b is a function that returns
// a pointer to a char
typedef b *c; // c is a pointer to a function
// that returns a pointer to a char
typedef c d(); // d is a function returning
// a pointer to a function
// that returns a pointer to a char
typedef d *e; // e is a pointer to a function
// returning a pointer to a
// function that returns a