坚固的构造函数语法

发布于 2025-01-21 15:25:57 字数 274 浏览 0 评论 0原文

浏览openzeppelin教程，我遇到了此代码片段：

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";

contract GameItem {
    constructor() ERC721("GameItem", "ITM") {}

构造函数中的语法是什么，可以在constructor（）之后传递类实例？我似乎在坚固的文档中找不到对此的任何参考

原文

Looking through an OpenZeppelin tutorial, I came across this code snippet:

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";

contract GameItem {
    constructor() ERC721("GameItem", "ITM") {}

What is the syntax in the constructor that allows a class instance to be passed in after constructor()? I can’t seem to find any reference to this in the Solidity docs

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筱武穆 2025-01-28 15:25:57

它正在调用父构建器，在这种情况下，父类被命名为erc721。它与调用super.constructor（）或parent.constructor（）中的其他一些语言相同。

为了致电父构建器，您的合同实际上需要从中继承：

contract GameItem is ERC721 {

坚固性支持多个父母的继承。这就是为什么您不能仅使用模棱两可的关键字，例如parent。通过明确说明父级名称，您可以指定要传递到哪个父的值：

pragma solidity ^0.8;

contract Parent1 {
    constructor(string memory message1) {}
}

contract Parent2 {
    constructor(string memory message2) {}
}

contract Child is Parent1, Parent2 {
    constructor() Parent1("hello") Parent2("world") {}
}

docs： https://docs.solitylang.org/en/v0.8.13/contracts.html#arguments-for-base-constructors

It's invoking a parent constructor, in this case the parent class is named ERC721. It's the same as calling super.constructor() or parent.constructor() in some other languages.

In order to call the parent constructor, your contract needs to actually inherit from it:

contract GameItem is ERC721 {

Solidity supports inheritance from multiple parents. That's why you cannot just use an ambiguous keyword such as parent. By explicitly stating the parent class name, you can specify which values you want to pass to which parent:

pragma solidity ^0.8;

contract Parent1 {
    constructor(string memory message1) {}
}

contract Parent2 {
    constructor(string memory message2) {}
}

contract Child is Parent1, Parent2 {
    constructor() Parent1("hello") Parent2("world") {}
}

Docs: https://docs.soliditylang.org/en/v0.8.13/contracts.html#arguments-for-base-constructors

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