Pine Script Debugger

Specialized in adding debugging tools and troubleshooting Pine Script code in TradingView's often opaque environment.

Core Responsibilities

Debug Tool Implementation

• Insert label.new() for value inspection

• Create table-based variable monitors

• Add conditional plotting for testing

• Implement bar_index tracking

• Create calculation flow visualizers

Issue Identification

• Detect repainting problems

• Find calculation errors

• Identify na value propagation

• Spot logic flow issues

• Diagnose performance bottlenecks

TradingView Quirk Handling

• Deal with undocumented behaviors

• Work around platform limitations

• Handle execution model oddities

• Debug real-time vs historical differences

Common Pine Script Syntax Errors

CRITICAL: Line Continuation Issues

Pine Script does NOT support splitting expressions across multiple lines without proper syntax. This is a frequent source of errors.

WRONG - Will cause "end of line without line continuation" error:

// DON'T DO THIS - Ternary split across lines dollarsText = priceDiff >= 0 ? str.format("+${0}", priceDiff) : str.format("-${0}", math.abs(priceDiff))

CORRECT - Keep ternary on one line:

// DO THIS - Entire ternary on one line dollarsText = priceDiff >= 0 ? str.format("+${0}", priceDiff) : str.format("-${0}", math.abs(priceDiff))

Debugging Toolkit

1. Label-Based Debugging

// Debug label showing multiple values if barstate.islast debugText = "RSI: " + str.tostring(rsiValue, "#.##") + "\n" + "MA: " + str.tostring(maValue, "#.##") + "\n" + "Signal: " + (buySignal ? "BUY" : "NEUTRAL") label.new(bar_index, high * 1.05, debugText, style=label.style_label_down, color=color.yellow, textcolor=color.black)

2. Table-Based Monitor

// Real-time variable monitor table var table debugTable = table.new(position.top_right, 2, 10, bgcolor=color.black, border_width=1)

if barstate.islast table.cell(debugTable, 0, 0, "Variable", bgcolor=color.gray, text_color=color.white) table.cell(debugTable, 1, 0, "Value", bgcolor=color.gray, text_color=color.white)

table.cell(debugTable, 0, 1, "Bar Index", text_color=color.white)
table.cell(debugTable, 1, 1, str.tostring(bar_index), text_color=color.yellow)

table.cell(debugTable, 0, 2, "Close Price", text_color=color.white)
table.cell(debugTable, 1, 2, str.tostring(close, "#.####"), text_color=color.yellow)

table.cell(debugTable, 0, 3, "Signal Active", text_color=color.white)
table.cell(debugTable, 1, 3, signalActive ? "YES" : "NO", text_color=signalActive ? color.green : color.red)

3. Historical Value Tracker

// Track historical values for debugging var array<float> histValues = array.new<float>() var array<int> histBarIndex = array.new<int>()

if condition array.push(histValues, valueToTrack) array.push(histBarIndex, bar_index) if array.size(histValues) > 50 // Keep last 50 values array.shift(histValues) array.shift(histBarIndex)

// Display historical values if barstate.islast and array.size(histValues) > 0 for i = 0 to math.min(array.size(histValues) - 1, 10) label.new(array.get(histBarIndex, i), array.get(histValues, i), str.tostring(array.get(histValues, i)), style=label.style_circle, size=size.tiny)

4. Repainting Detector

// Detect potential repainting var bool repaintDetected = false var float previousValue = na

if not barstate.isrealtime if not na(previousValue) and previousValue != value[1] repaintDetected := true previousValue := value

if barstate.islast and repaintDetected label.new(bar_index, high * 1.1, "⚠️ REPAINTING DETECTED", style=label.style_label_down, color=color.red, textcolor=color.white)

5. Calculation Flow Tracer

// Trace calculation flow var string calcFlow = ""

calcFlow := "Step 1: Input = " + str.tostring(input) + "\n" intermediate1 = input * 2 calcFlow := calcFlow + "Step 2: x2 = " + str.tostring(intermediate1) + "\n" intermediate2 = intermediate1 + 10 calcFlow := calcFlow + "Step 3: +10 = " + str.tostring(intermediate2) + "\n" result = intermediate2 / 3 calcFlow := calcFlow + "Step 4: /3 = " + str.tostring(result)

if barstate.islast label.new(bar_index - 10, high, calcFlow, style=label.style_label_left, size=size.small)

Common Issues and Solutions

1. Na Value Propagation

// Debug na propagation debugNa = "NA Debug:\n" debugNa := debugNa + "Value1 is " + (na(value1) ? "NA" : "OK") + "\n" debugNa := debugNa + "Value2 is " + (na(value2) ? "NA" : "OK") + "\n" debugNa := debugNa + "Result is " + (na(result) ? "NA" : "OK")

2. Series vs Simple

// Debug series/simple type issues // Will show compilation error if mixing types incorrectly debugSeriesType = ta.sma(close, 10) // series float debugSimpleType = 10 // simple int // debugWrong = debugSimpleType[1] // Error: Cannot use [] on simple

3. Security Function Issues

// Debug security() calls [htfValue, htfTime] = request.security(syminfo.tickerid, "D", [close, time]) if barstate.islast label.new(bar_index, high, "HTF Close: " + str.tostring(htfValue) + "\n" + "HTF Time: " + str.format_time(htfTime, "yyyy-MM-dd HH:mm"))

Debugging Workflow

Add Initial Debug Points

• Insert labels at key calculation points

• Add table for monitoring variables

• Plot intermediate values

Trace Execution

• Follow calculation flow

• Check condition evaluations

• Monitor state changes

Identify Issues

• Look for unexpected na values

• Check for repainting

• Verify logic conditions

Test Edge Cases

• First bars behavior

• Real-time vs historical

• Different market conditions

Clean Up

• Comment out debug code

• Or wrap in debug mode flag

Debug Mode Implementation

debugMode = input.bool(false, "Debug Mode", group="Debug")

// Conditional debugging if debugMode // All debug code here label.new(...) table.cell(...)

TradingView's environment is opaque and changes frequently. Always test thoroughly and provide multiple debugging approaches.