> For the complete documentation index, see [llms.txt](https://chihaolu.gitbook.io/all-in-one-solidity/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chihaolu.gitbook.io/all-in-one-solidity/part-ii-medium/chapter-10-shi-jian-event/anonymous.md).

# 【anonymous】

* `anonymous`: 不會儲存任何的事件的 `signature` 在 `topics` 內

不同於一般的 `events`，匿名事件不會包含任何 `indexed` `signature` 的 `keccak` 加密結果。因為他們不可以被簡單地搜尋或被特別地解密，除非我們擁有合約 ABI。

要使一個合約為匿名（`anonymous`）可以在每個變數後面加上 `anonymous`：

```solidity
contract TestContract {
    event Start(uint start, uint middle, uint end) anonymous;
    event End(uint start, uint middle, uint end) anonymous;
```

在 Solidity 中匿名 `event` 會耗費較少的成本，然而我們不能夠使用 name 找到他們，只能使用特定的 contract address:

```solidity
pragma solidity >=0.4.21 <0.7.0;

contract ClientReceipt {
    event Deposit(
        address indexed _from,
        bytes32 indexed _id,
        uint _value
    );

    function deposit(bytes32 _id) public payable {
        // Events are emitted using `emit`, followed by
        // the name of the event and the arguments
        // (if any) in parentheses. Any such invocation
        // (even deeply nested) can be detected from
        // the JavaScript API by filtering for `Deposit`.
        emit Deposit(msg.sender, _id, msg.value);
    }
}
```


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