Difference between revisions of "Compiler issues"

Latest revision as of 21:02, 12 November 2011

Like any other compiler there are issues with the parsing therefor this page exists to mention those common issues and how to get around them.

Parsing Issues[edit]

Comment Issues related to the comments

Having an end of multi-line comment proceeded by a line comment on the same line.

/*  if(!bUseForVehicles) 
        return Super.DamageTaken(Enemy, Injured);
    else{//Branch4: Do vehicle code here, optimized?}
*/

/*local int LogInitHealth;*/ /*, LogDamage, LogConversion;*/

/*  if(!bUseForVehicles) 
        return Super.DamageTaken(Enemy, Injured);
    else{//Branch4: Do vehicle code here, optimized?}*/

/*local int LogInitHealth;*//*, LogDamage, LogConversion;*/

DefaultProperties Issues related to the defaultproperties block

Placing a { on the same line of the defaultproperties declaration will cause the parser to skip the defaultproperties block thus :all of your default values will not be compiled, to get around this is easy just place the { on the next line!.

defaultproperties
{
}

defaultproperties{
}

Switch Issues related to the switch block when attempting to access DefaultProperties from a static function.

Using the syntax Default.Identifier (to resolve a DefaultProperties reference from a static function) within a switch block confuses the compiler, which assumes the script has an error, and suggests 'default:', as in the default case for a switch statement. The error message is Error, Missing ':' in 'Default. See examples for some workarounds.

// A workaround is necessary.
// Example using the class name directly..
case 1:
  Class'GameMessage'.Static.CallMe ();
  break;
// ..or an if-else block to replace the switch-case statement..
// ..or a local proxy variable:
static function Test (int Index)
{
  local class<LocalMessage> ClassNameWorkaround;
  ClassNameWorkaround = Default.ClassName;
  // ...
    case 1:
      ClassNameWorkaround.Static.CallMe ();
      break;
// ...
}

var class<LocalMessage> ClassName;
 
static function Test (int Index)
{
  switch (Index)
  {
    case 1:
      Default.ClassName.Static.CallMe ();
      break;
 
    default:
      break;
  }
}
 
DefaultProperties
{
  ClassName = Class'GameMessage'
}

DefaultProperties Issues related to the defaultproperties block and the mathematical syntax for representing negative numbers. No warnings from the compiler.

In mathematics, a negative number is sometimes represented in parenthesis, as in the expression 1 + (-1). The parenthesis are not recognized, and thus the value becomes 0.0f (default-initialized).

var float A;
 
DefaultProperties
{
  A = -1.0f
}

var float A;
 
DefaultProperties
{
  A = (-1.0f) // A is 0.0f
}

DefaultProperties Issues related to the defaultproperties block and const values. No warnings from the compiler.

A const value would appear default-initialized (0.0f, 0, false) when used in a defaultproperties block.

var float A;
 
DefaultProperties
{
  A = 2.71828f
}

var float A;
const C = 2.71828f;
 
DefaultProperties
{
  A = C // A is 0.0f
}