E10010: 'void' return type cannot be used with an assignment

What went wrong

You're trying to use a VOID function's result in an assignment or expression. Void functions don't return values.

Worked examples

Compilable examples demonstrating this error and the correct fix:

• ek9 -q 941 (Why can't I assign the result of a void function in E...)

How to fix it

1. Add return value to function if needed
2. Or don't try to capture void result

The [EXAMPLE] section below shows a void function's result held in a variable, and the call made on its own beside a function that does return a value.

Common causes

• Assigning result of procedure-like function
• Using void function in expression

See also

• E10010: void result in assignment (this error)
• E10020: void in stream pipeline

Examples

Every example is compiled by the EK9 compiler: the first fails exactly as captioned, the others fix it.

Fails with E10010: 'void' return type cannot be used with an assignment

#!ek9
defines module error.e10010.bad

  defines function

    logItem()
      -> item as String
      stdout <- Stdout()
      stdout.println(item)

    process()
      outcome <- logItem("first")
      require outcome?

Fixed: Call it as a statement, or give it a returning variable

#!ek9
defines module error.e10010.good

  defines function

    logItem()
      -> item as String
      stdout <- Stdout()
      stdout.println(item)

    describe()
      -> item as String
      <- rtn as String: `item: ${item}`

    process()
      logItem("first")
      outcome <- describe("second")
      logItem(outcome)

Questions and answers

These Q&A entries show E10010 and its fix:

• Q941: Why can't I assign the result of a void function in EK9?