Pine script Pine脚本获取一个位置中的条数

我试着根据进场时的摆低来确定静态止损。但当我尝试以下方法时，止损随着每个小节不断变化，因为出现了新的最低点

SwingLowBars=20

longStop = lowest(low, SwingLowBars)[1]

longTake = strategy.position_avg_price + ((strategy.position_avg_price-longStop)*3)

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我想要一个函数，在每一根新蜡烛处于该位置时，不断向SwingGlowBars变量添加+1，这样当最低的棒距超过20棒时，longTake保持静止且不发生变化

您可以在“var”变量中记住SL值：

// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © adolgov

//@version=4
strategy("My Strategy", overlay=true)

longCondition = crossover(sma(close, 14), sma(close, 28))
if (longCondition)
    strategy.entry("My Long Entry Id", strategy.long)

SwingLowBars=20
longStop = lowest(low, SwingLowBars)[1]
var sl = float(na)
if strategy.position_size !=0 and strategy.position_size[1] == 0
    sl := strategy.position_avg_price - ((strategy.position_avg_price-longStop)*3)
    
strategy.exit("x", stop = sl)