ethereum(以太坊)(二)--合约中属性和行为的访问权限

pragma solidity ^0.4.0;

contract Test{
    /* 属性的访问权限
    priveta public internal
    defualt internal
    interlnal,private cannot be accessed from outside
    */
    uint8 internal _money;
    uint8 _age;
    uint8 private _height;
    uint8 public _sex;
    
    /*uint8 public _sex == function _sex() returns(uint8) 
    当属性类型为public时,会生成一个和属性名相同并且返回值就是当前属性的get函数
    function _sex()函数会覆盖掉public类型的属性自动生成的get函数;_sex()返回的是1,而不是0
    */
    function _sex() returns(uint8){
        //return _sex;
        //this._age; return this.age();TypeError: Member "age" not found or not visible after argument-dependent lookup in contract Test
        this._sex();
        return 1;
    }
    
    /*方法的访问权限
    //public private internal external
    //defualt public
    //internal private cannot be accessed from outside
    */
    function sex() returns(uint8){
        return 1;
    }
    function age() internal returns(uint8){
        return 18;
    }
    function height() public returns(uint8){
        return 175;
    }
    function money() private returns(uint){
        return 3500;
    }
    
    function year() external returns(uint){
        return 2018;
    }
    
    function testInternal() returns(uint){
        //return this.sex();
        //return this.year(); this(指针) 通过合约地址进行访问 
        return money();
        //return this.age();TypeError: Member "age" not found or not visible after argument-dependent lookup in contract Person
        //
    }
}

无论是属性还是方法,只有是public/external类型时,才可以通过合约地址进行访问,合约内部的this就是当前合约地址。
在合约内部如果要访问internal,private类型的属性或者是函数,直接访问即可,不要试图通过this去访问

 

//本合约内部调用
//this.external调用 
function test() public{
    getC(); //interl
    this.getD();//external
    getE();//private
    this.kill();//public
    kill();//public
}

//未使用继承,外部调用
//只能调用external/public
contract mytract{

function getA() public {
    **getC(); //interl
    this.getD();//external
    **getE();//private
    this.kill();//public
    **kill();//public
    }
  }

//使用继承,外部调用
//无法调用私有变量
contract mytract is Funder{
    
    function getA() public {
        getC(); //interl
        this.getD();//external
        **getE();//private
        this.kill();//public
        kill();//public
    }
}