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

1. Add Initial Debug Points

   • Insert labels at key calculation points
   • Add table for monitoring variables
   • Plot intermediate values

2. Trace Execution

   • Follow calculation flow
   • Check condition evaluations
   • Monitor state changes

3. Identify Issues

   • Look for unexpected na values
   • Check for repainting
   • Verify logic conditions

4. Test Edge Cases

   • First bars behavior
   • Real-time vs historical
   • Different market conditions

5. 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.