Cocos Basic Tutorial (4) Data structure introduction of Cocos2d::value

1. Overview

Cocos2d::valie is a containing many native types (int,float,double,bool,unsigned char,char* and std::string) plus STD::VECTOR<VALUE> STD Classes of::unordered_map<std::string,value> and std::unordered_map<int,value>.

You can put all of the above mentioned native types into the Cocos2d::value object, and then convert them to the corresponding native type, and vice versa.

Internally, Cocos2d::value uses a union variable to hold various native types, which can save a lot of memory space.

2. Memory Management

Cocos2d::value's memory is automatically processed by its own destructor. So stick with the C + + memory management rules for best practices when dealing with cocos2d::value memory.
The Cocos2d::value class contains the following data members:

 union{unsigned  char   Byteval;     int   Intval;     float   Floatval;     double   Doubleval;  bool   Boolval;} _basedata; std::  string   _strdata; Valuevector  * _vectordata; ValueMap  * _mapdata; Valuemapintkey  * _intkeymapdata; Type _type;  

As you can see from the code snippet, the memory of the _basedata,_strdata and _type data members is handled automatically by the compiler and their destructors. Cocos2d::value's destructor is responsible for releasing resources (_vectordata,_mapdata and _intkeymapdata) for all pointer member variables.
Warning: cocos2d::value no longer uses retain/release and reference count memory management like other cocos2d classes.

3. Basic usage

The use of Cocos2d::value is very simple.
A simple example is provided here:

Value Val;//calling the default constructorif(Val.isnull ()) {log ("Val is null");}Else{std::stringstr =val.getdescription (); Log ("The description of val0:%s", Str.c_str ());}//----------------------------------------------------Value Val1 ( $);//initialize with an int//Value val1 (3.4f); //initialize with a float//Value Val1 (3.5); //initialize with a doubleLog"The description of the integer value:%s", Val1.getdescription (). C_STR ()); Log ("val1.asbyte () =%c", Val1.asbyte ());//----------------------------------------------------STD::stringSTRV ="string";   Value Val2 (STRV); //Initialize with stringLog"The description of the string value:%s", Val2.getdescription (). C_STR ());//----------------------------------------------------Auto SP0 =sprite::create (); Vector<object*>* VECV =NewVector<object*>(); Vecv-pushback (SP0);   Value Val3 (VECV); //Initialize with VectorLog"The description of the Vector value:%s", Val3.getdescription (). C_STR ());DeleteVecv;//----------------------------------------------------MAP&LT;STD::string, object*>* MAPV =NewMAP&LT;STD::string, object*>(); MAPV-Insert (STRV,SP0);   Value Val4 (MAPV); //Initialize with MapLog"The description of the Map value:%s", Val4.getdescription (). C_STR ());DeleteMAPV;//----------------------------------------------------Value val6 (&AMP;VAL4);//Initialize with MapLog"The description of the value-type value:%s", Val6.getdescription (). C_STR ());//----------------------------------------------------Val2 = Val1;//assign a value between two different reference typesLog"operator-> The description of val2:%s", Val2.getdescription (). C_STR ()); Val2=4;//Direct AssignmentLog"operator-> The description of val4:%s", Val2.getdescription (). C_STR ());

Output results

Cocos2d:val isNULLcocos2d:the Description of the integer value: $Cocos2d:val1.asByte ()=acocos2d:the Description of thestringValue:stringcocos2d:the Description of the Vector value:truecocos2d:the Description of the Map value:truecocos2d:the Description of the Value-Type value:trueCocos2d:operator-The description of Val2: $Cocos2d:operator-The description of Val4:4

4. Best practices

• Prefer to use cocos2d::value and new template containers (cocos2d::vector<t> and cocos2d::map<k,v>) instead of using cocos2d::ccbool,cocos2d:: Ccfloat,cocos2d::ccdouble,cocos2d::ccstring,cocos2d::ccinteger and old objective-c style containers (Cocos2d::ccarray and cocos2d:: Ccdictionary).
• When you want to handle collections of native types, use Cocos2d::value to encapsulate native types and then combine them with the new template container cocos2d::vector<t> and cocos2d::map<k,v>.

Cocos Basic Tutorial (4) Data structure introduction of Cocos2d::value