//@version=5 indicator("Lesson 8 - Functions", overlay=false) //@function Percent change of a series over a lookback window. //@param src The series to measure. //@param lookback Number of bars back. //@returns Percent change as a float series. percentChange(src, lookback) => (src - src[lookback]) / src[lookback] * 100 // Same function, two lookbacks. pct20 = percentChange(close, 20) pct50 = percentChange(close, 50) plot(pct20, "20-bar % change", color=color.blue, linewidth=2) plot(pct50, "50-bar % change", color=color.orange, linewidth=2) hline(0, "Zero", color=color.gray, linestyle=hline.style_dotted) bgcolor(pct20 > 0 ? color.new(color.green, 90) : color.new(color.red, 90))

函式的形狀

一個 Pine 函式吃有型別的輸入並回傳一個值。最簡單的：

percentChange(src, lookback) =>
    (src - src[lookback]) / src[lookback] * 100

這是一個函式字面值——用 => 的一行式。用它：plot(percentChange(close, 20))。

多行函式

任何不簡單的東西都用區塊形式：

atrPercent(length) =>
    atr = ta.atr(length)
    atr / close * 100

plot(atrPercent(14))

用 tuple 回傳多個值

Pine v5 的函式可以回傳 tuple：

macdSignal(src, fast, slow, signalLen) =>
    fast_ma = ta.ema(src, fast)
    slow_ma = ta.ema(src, slow)
    macd = fast_ma - slow_ma
    sig = ta.ema(macd, signalLen)
    [macd, sig]

[m, s] = macdSignal(close, 12, 26, 9)
plot(m)
plot(s)

文件字串

Pine 支援放在函式上方的文件註解：

//@function        Returns the percent change of a series over a lookback window.
//@param src       The series to measure
//@param lookback  Number of bars back
//@returns         The percent change as a float series
percentChange(src, lookback) =>
    (src - src[lookback]) / src[lookback] * 100

在編輯器裡把游標停在函式呼叫上就會顯示文件。

函式要放哪裡

腳本最上面，在任何呼叫它們的程式碼之前。函式可以呼叫其他函式。這裡沒有「標頭檔」——Pine 是單一檔案語言。

這解鎖了什麼

一旦你為常用的積木（自訂均線、訊號產生器、sizing 邏輯）寫好函式，每一個新策略就變成「組合函式、畫出訊號」，而不是從頭寫同一套數學。