QR code (Quick Respone Code)
Also referred to as QR code, which is a two-dimensional planar pattern of small squares composed of two different colors, which is a data (typically a string) is encoded as a two-dimensional code image scanner can quickly identify dimensional code image data (i.e., decode)
Variable scope (Scope) problem
Scoped variables: Code scope variables can be accessed
According to different scopes, variables can be divided into local and global variables (Free Join)
Python interpreter cited in the search argument is to comply with the rules LEGB
L: Local, i.e. internal functions scope
E: Enclosing, the outer nested function scopes
G: Global, global scope
B: Built-in, built-in scope
In addition to the function calls can be nested, nested definitions may
Closure (Enclosing)
Local variables defined inside remain after the function returns
To achieve the defined function must be nested closure
Version Control System
Version Control System, referred to as VCS, mainly to solve the problem of file version management, divided into centralized and distributed VCS VCS
Centralized VCS: SVN, etc.
Distributed VCS: GIT, etc.
Master the common usage of GIT
GIT three important concepts: work areas, staging areas, warehouse
git log View Log
git reflog view operating information for all changes warehouse
git status to view the status of the work area
git reset --hard HEAD return to the last change
Object-Oriented Programming
Oriented Object Programming, referred to as of OOP, a programming idea, that the basic units of OOP program object (instance), the interaction between different objects to achieve the various functions of the program
Process-oriented programming function that is a basic unit constituting the program, the order of execution of a set of functions to achieve the various functions of the program
OOP is a programming language development trend
OOP is achieved by classes and objects; objects (Object) is also called an instance (instance), any particular things are an object class (Class) having the same attributes (the Attribute, i.e., data) and methods (Method,, That behavior) of all objects or abstract collection
From the perspective of data types, the class is actually a custom data type, and the object is the data belongs to a specific data type
restriction of visit
One or two names begin with an underscore are private properties and methods represent, that they can only be accessed in the class, do not access them outside the class, although Python does not provide grammar rules to ensure this, but we have to consciously abide!
Property (Attribute)
Examples of attributes are divided into (Instance Attribute) and class attributes (Class Attribute), all belonging to the object instance properties, each object has its own independent of a property can only be accessed through the object name, and property belonging to the class of all classes, all objects a shared, can be accessed through the class and object names
In the actual development, to avoid class instance attributes and attributes with the same name
Spread
In addition to 1.Python object class has no parent rest
2.windows below begins with a dot is not a hidden file, but the file is hidden attribute
3. The root causes of garbage generated: codec is inconsistent, it is recommended to use a unified utf-8
Here 4.windows newline is \ r \ n, Linux is below newline \ n
5.vim into the automatic formatting ctrl + v = visualized by two to
6. The binary conversion! !