[Tutorial] Debugging Scripts in Scripting

Looking at the WaW Scripting Support forum section, it seems like a lot of problems can be solved quite easily without much help if doing some debugging. This tutorial is easy enough that you don't need much scripting knowledge, if anything, it'll let you post valuable information when seeking help for people to better assist you.

I'll try to keep this thing updated over time (and cross-posted between UGX and ZM forums) if I see more common issues arise in the support section or someone has a specific debugging question or technique they want to know about.

Running The Game In Developer Mode

First off, you want to run some dvars when working on your map / mod. These are the ones I recommend ALWAYS using when developing your content:

set developer 2 set developer_script 1 set thereisacow "1337" set logfile 2 devmap <mapname>

Zombies Debugging

In addition to running the game in developer mode, you can use for zombie related development tools:

set zombie_cheat <1-5>

1		Start all players with 100000 points
2		Start all players with 100000 points don’t spawn any zombies
3		Start all players with 100000 points turn on the power after 5 seconds
4		Points no zombies power after 5 seconds
5		Same as 4 the ability to re-buy the same perk over and over. Useful for testing animations, sounds, etc.

Checking Logfile

Everything that is printed to the console is printed to the console.log file which goes in the main folder by default. If you're running a mod, the console.log will be in your mod folder within the installation directory.

If you're posting an error on the forum or for someone to fix, it's generally a good idea to attach this file since it'll contain all the console information of what went wrong like a callstack.

Script Runtime Errors

When running your map in developer mode, if you encounter a Script Runtime Error (SRE) the game will end the map if it's fatal or bring up a pop-up window if it's non-fatal.

If you have a SRE you should ALWAYS address them to get a proper fix in -- don't assume since people playing your map won't be running developer mode the issue goes away. It is still happening in the background and can cause really bad issues like hitching, unexpected script results, or even crashing your map.

They usually look like this:

Quote

******* script runtime error *******
undefined is not an array, string, or vector: (file 'maps/mp/_load.gsc', line 113)
if (!isdefined(level._effect["lantern_light"]))
*
called from:
(file 'maps/mp/_load.gsc', line 12)
lanterns thread lanterns();
*
called from:
(file 'maps/mp/mp_houses22.gsc', line 2)
mapsmp\_load::main();
*
started from:
(file 'maps/mp/mp_houses22.gsc', line 1)
main() {
*
************************************

The way it's displayed is the bottom is the origin of the script routine, and the very top is where the SRE was encountered.

In the above example, the map main() function calls the _load.gsc main() function which calls the _load.gsc lanterns() function which has an error on line 113 with the lantern FX.

Note: The formatting is off in how the forum shows this, but the asterisk (*) will always be under the variable / function with the error. It'll display properly in-game to give you a better idea what part of the line is problematic.

Assertions

Asserts are a development feature that check if a condition is true and if not, stops the game. This is useful for when you as a designer want to validate your assumptions about what the state of the game should be whenever possible.

Example:

Code Snippet

Plaintext

AssertEx( IsDefined( ai_maxis), "Maxis AI did not spawn." );

These have no impact in non-developer mode, so people playing your map will never trigger them... but they may run into a SRE. In that case, you should avoid defensive coding to get around the issue and instead fix the issue; if something shouldn't happen, then an assertion is the right thing to use.

Here are the various Assert API you have at your disposal:

Assert( <value> );		Assert that the given statement is correct. The function will throw a script error if this is false.
AssertEx( <value>, <message> );		Assert that the given statement is correct. The function will throw a script error if this is false, with the given message.
AssertMsg( <message> );		Throws a script error with the given message.

Dev Blocks

If you want certain script snippets to only execute when in developer mode, you can wrap in /# #/

This is useful if you want to kick off developer functions or do prints to the screen of information you want to see from script. People playing your map won't see these.

Example:

Code Snippet

Plaintext

	while ( true )
	{
		trig waittill( "trigger", who );
		{
			/#
			IPrintLnBold( "Player who purchased perk: "   who.playername );
			#/
		}
	}

Common SREs

Quote

could not find script <script_name_here>

You don't have the script in a FastFile or IWD that is being loaded by the map.

Quote

must be applied to an int (applied to undefined)

You'tr trying to do a mathematical operation on a variable that isn't defined before the operation. You can't initiate a variable while doing the mathematical operation, you need to define it earlier even if it's just a zero.

Quote

undefined is not an array, string, or vector

Variable you're trying to reference is empty.

Quote

cannot set field of removed entity

Entity has left / deleted from the game or the entity variable it was stored in has been reset / undefined.

Quote

cannot cast undefined to <variable_type_here>

You're trying to reference a variable that is empty.

Quote

potential infinite loop in script

Your while or for loop doesn't have a wait in it. Every loop needs a wait, whether it be a timed wait of 0.05 seconds or waiting for a notify.


	Benevolent Soul who has our eternal gratitude and exclusive access to betas and the donator section of the forum.
	Has shown excellence and experience in the area of custom scripting in the UGX-Mods community.
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	Has released one or more maps to the UGX-Mods community which have been added to the UGX Map Manager.

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[Tutorial] Debugging Scripts