Why does the compiler reject my variable name?

← Variable Naming Rules and Conventions · Ref: Q291

EK9 rejects variable names that are non-descriptive or shadow operators. Each error code tells you exactly what category of restriction you hit.

E11031: NON-DESCRIPTIVE VARIABLE NAME

You used one of: temp, tmp, flag, flg, data, dat, object, obj, value, val, buffer, buf. The check is case-insensitive. Fix: describe what the variable represents. Instead of temp use swapHolder or intermediateResult. Instead of flag use isComplete or shouldRetry. Instead of data use customerRecord or sensorReading. Instead of value use totalPrice or measuredWeight. Instead of buffer use outputBuilder or readChunk.

E11032: OPERATOR KEYWORD AS VARIABLE NAME

You used one of: empty, length, contains, abs, sqrt, close, matches. These shadow built-in operators. Fix: add context. Instead of empty use isBlank or emptyBasket. Instead of length use nameLength or pathSize. Instead of contains use hasItem or includesKey. Instead of matches use foundItems or searchHits. Instead of abs use absoluteDistance. Instead of close use closeFile or shutdownConnection.

E01060: RESERVED WORD AS IDENTIFIER

You used assert, require, assertThrows, or assertDoesNotThrow. These are reserved for the testing framework. Fix: use testResult, precondition, or validationCheck instead.

E01070-E01080: EXCLUDED KEYWORD

You used break, continue, return, null, goto, new, def, elif, None, or self. These keywords do not exist in EK9. Fix: these are not just naming issues, they indicate you are thinking in another language. See Q144 for why EK9 has no break, continue, or return.

QUICK FIX TABLE

  temp/tmp -> swapHolder, intermediateResult, pendingEntry
  flag/flg -> isComplete, hasPermission, shouldRetry
  data/dat -> customerRecord, sensorReading, responsePayload
  object/obj -> currentItem, targetEntity, parsedElement
  value/val -> totalPrice, measuredWeight, userInput
  buffer/buf -> outputBuilder, messageAccumulator, readChunk
  empty -> isBlank, emptyBasket, noResults
  length -> nameLength, pathSize, messageCount
  contains -> hasItem, includesKey, foundMatch
  matches -> foundItems, matchingRecords, searchHits

See Q290 for the complete banned list. See Q297 for a comprehensive renaming guide. See Q248 for all error codes.

Example

defines module qa.naming.troubleshoot

  defines function

    processOrder() as pure
      ->
        orderTotal as Float
        customerName as String
      <- receiptMessage as String: `Order for ${customerName}: ${orderTotal}`

    calculateDiscount() as pure
      ->
        originalPrice as Float
        discountRate as Float
      <- discountedPrice as Float: originalPrice * (1.0 - discountRate)

    retryUntilDone()
      -> maxAttempts as Integer
      <- attemptCount as Integer: 0

      isRetryNeeded <- Boolean(true)
      while isRetryNeeded and attemptCount < maxAttempts
        attemptCount++
        if attemptCount >= maxAttempts
          isRetryNeeded: false

  defines program

    TroubleshootNamingDemo()
      stdout <- Stdout()

      // === FIXED E11031: temp -> swapHolder ===

      firstNumber <- 10
      secondNumber <- 20
      swapHolder <- firstNumber
      firstNumber := secondNumber
      secondNumber := swapHolder
      stdout.println(`After swap: ${firstNumber}, ${secondNumber}`)

      // === FIXED E11031: flag -> isRetryNeeded ===

      attemptCount <- retryUntilDone(3)
      stdout.println(`Attempts: ${attemptCount}`)

      // === FIXED E11031: data -> customerRecord ===

      customerRecord <- "Alice:Premium:2024"
      stdout.println(`Record: ${customerRecord}`)

      // === FIXED E11032: empty -> emptyBasket ===

      emptyBasket <- List() of String
      stdout.println(`Empty basket: ${emptyBasket}`)

      // === FIXED E11032: length -> nameLength ===

      greeting <- "Hello, World"
      nameLength <- length greeting
      stdout.println(`Name length: ${nameLength}`)

      // === COMBINED EXAMPLE: GOOD NAMING THROUGHOUT ===

      originalPrice <- 100.0
      discountRate <- 0.15
      finalPrice <- calculateDiscount(originalPrice, discountRate)
      receiptMessage <- processOrder(finalPrice, "Alice")
      stdout.println(receiptMessage)

Common mistakes

E11031 — The name 'temp' is non-descriptive and banned by the compiler. Use 'swapHolder' or another name that describes the variable's purpose. See ek9 -h E11031 for details.

Incorrect:

temp

Correct:

swapHolder

E11032 — The name 'length' shadows a built-in operator keyword and is rejected. Use a descriptive alternative like 'nameLength'. See ek9 -h E11032 for details.

Incorrect:

length

Correct:

nameLength

E11031 — The name 'data' is non-descriptive and banned. Use a name like 'customerRecord' that describes what the data represents. See ek9 -h E11031 for details.

Incorrect:

data

Correct:

customerRecord

Coming from another language?

Java: no compile-time naming enforcement, Checkstyle rules are optional and configurable. Python: no naming enforcement, PEP 8 is advisory. Rust: no naming enforcement beyond snake_case warnings. Go: no naming enforcement, golint is advisory. C/C++: no naming enforcement. Kotlin: no naming enforcement. JavaScript: ESLint naming rules are optional. EK9: compiler enforces naming at compile time, cannot be disabled, four tiers of restrictions with specific error codes.

Keywords: naming, E11031, E11032, error, why, identifier, troubleshoot, E01060, compiler, banned, reject, rename, variable, fix, compile, convention