# 策略使用案例

## A. 案例1：帶有 AlertCondition() + Alert 手動設定的 MACD 腳本

要建立一個警報，需要定義觸發它的條件。這個條件可以基於各種因素，如價格、指標或自訂邏輯。以下使用 Pine Script 語言，以 MACD 技術指標作為範例。

```javascript
//@version=5
indicator('MACD Sample Script 1', overlay=true)

// Calculate MACD
[macdLine, signalLine, _] = ta.macd(close, 12, 26, 9)

// Define the golden cross condition
goldenCross = ta.crossover(macdLine, signalLine)

// Define the death cross condition
deathCross = ta.crossunder(macdLine, signalLine)

// Use the alertcondition function to generate alerts
alertcondition(condition=goldenCross, title="MACD Golden Cross", message="")
alertcondition(condition=deathCross, title="MACD Death Cross", message="")
```

在這個例子中，我們首先使用 `ta.macd()` 函數計算 MACD 指標，該函數接受輸入序列（在本例中為收盤價）和 MACD 的參數（12、26、9）。然後我們分別使用 `ta.crossover()` 和 `ta.crossunder()` 函數定義了黃金交叉和死亡交叉的條件。當 MACD 線穿過信號線**上方**時，發生黃金交叉；而當 MACD 線穿過信號線**下方**時，發生死亡交叉。

***

## B. 案例2：帶有 Alert() 訊息嵌入的 MACD 腳本

不使用 `alertcondition()`，我們使用 `alert()` 函數在滿足條件時直接生成警報。

```javascript
//@version=5
indicator('MACD Sample Script 2', overlay=true)

// Calculate MACD
[macdLine, signalLine, _] = ta.macd(close, 12, 26, 9)

// Define the golden cross condition
buySignal = ta.crossover(macdLine, signalLine)

// Define the death cross condition
sellSignal = ta.crossunder(macdLine, signalLine)

// Function to generate custom JSON payload
get警報訊息(action, instrument, signalToken, orderType, orderPriceOffset, investmentType, amount) =>
    str = '{'
    str := str + '"action": "' + action + '", '
    str := str + '"instrument": "' + instrument + '", '
    str := str + '"signalToken": "' + signalToken + '", '
    str := str + '"timestamp": "' + str.tostring(timenow) + '", '
    str := str + '"orderType": "' + orderType + '", '
    str := str + '"orderPriceOffset": "' + str.tostring(orderPriceOffset) + '", '
    str := str + '"investmentType": "' + investmentType + '", '
    str := str + '"amount": "' + str.tostring(amount) + '"'
    str := str + '}'
    str

var ALERTGRP_CRED = "BitFrog Alert - Credential"
signalToken = input("", "Signal Token", inline = "11", group = ALERTGRP_CRED)

var ALERTGRP_ENTER = "BitFrog Alert - ENTER Signal"

enterOrderType = input.string("market", "Order Type", options = ["market", "limit"], inline = "21", group = ALERTGRP_ENTER)
enterOrderPriceOffset = input.float(0, "Order Price Offset", minval = 0, maxval = 100, step = 0.01, inline = "21", group = ALERTGRP_ENTER)

enterInvestmentType = input.string("percentage_balance", "Investment Type", options = ["margin", "contract", "percentage_balance", "percentage_investment"], inline = "31", group = ALERTGRP_ENTER)
enterAmount = input.float(100, "Amount", minval = 0.01, inline = "31", group = ALERTGRP_ENTER)

var ALERTGRP_EXIT = "BitFrog Alert - EXIT Signal"

exitOrderType = input.string("market", "Order Type", options = ["market", "limit"], inline = "41", group = ALERTGRP_EXIT)
exitOrderPriceOffset = input.float(0, "Order Price Offset", minval = 0, maxval = 100, step = 0.01, inline = "41", group = ALERTGRP_EXIT)

exitInvestmentType = input.string("percentage_position", "Investment Type", options = ["percentage_position"], inline = "51", group = ALERTGRP_EXIT)
exitAmount = input.float(100, "Amount", minval = 0.01, maxval = 100, step = 0.01, inline = "51", group = ALERTGRP_EXIT)

if buySignal
    buy警報訊息 = get警報訊息(action = 'open_long', instrument = syminfo.ticker, signalToken = signalToken, orderType = enterOrderType, orderPriceOffset = enterOrderPriceOffset, investmentType = enterInvestmentType, amount = enterAmount)
    alert(buy警報訊息, freq = alert.freq_once_per_bar)

if sellSignal
    sell警報訊息 = get警報訊息(action='close'/action='open_short', instrument = syminfo.ticker, signalToken = signalToken, orderType = exitOrderType, orderPriceOffset = exitOrderPriceOffset, investmentType = exitInvestmentType, amount = exitAmount)
    alert(sell警報訊息, freq = alert.freq_once_per_bar)
```

`get警報訊息` 函數是為了生成一個客製化的 JSON 負載，來按照 BitFrog 訊息規格的格式發送警報。輸入包括 `signalToken`、`enterOrderType`、`enterOrderPriceOffset`、`enterInvestmentType`、`enterAmount`、`exitOrderType`、`exitOrderPriceOffset`、`exitInvestmentType` 和 `exitAmount`。這些輸入用於指定警報的訂單類型、價格偏移量、投資類型和金額。

然後，程式碼使用 `buySignal` 和 `sellSignal` 條件來檢查買入和賣出信號。如果發生買入信號，它透過呼叫帶有適當參數的 `get警報訊息` 函數生成買入警報訊息。警報訊息包括行動（`'open_long'`）、交易工具（當前的股票符號）、信號令牌和指定的輸入變數的資訊。同樣，如果發生賣出信號，它會使用 `get警報訊息` 函數生成賣出警報訊息，並使用 `alert()` 函數發送訊息。

> **作為使用者**，如果你想從 MACD 黃金交叉／死亡交叉切換到另一種邏輯，你需要做的就是更換 `buySignal` 和 `sellSignal` 的定義，其他所有的東西都可以直接複用。說得更直白一些，**如果你想改變買賣信號的判斷依據，只需要修改買賣信號的定義就行了，其他的都不用改**。


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