godot: Make preload invalid paths null instead of a compilation error

Operating system or device - Godot version: Windows 10 Godot 2.1 stable

Issue description: The current behavior of preload with invalid paths is give an error in editor (Can’t preload resource at path) and crash at runtime. xh5vlyr 1 A better approach could be instead of give an error in editor and crash at runtime, preload could return null and let the user check ingame if the preloaded var/const is null.

This could be useful for addons, for example I have an addon which has a timer created by script for delayed triggers and I wan’t the trigger addon to be independant from the project, but for this project the timer could be paused with a player ability, so I need a way to attach that script for the timer in the trigger. The easiest and optimal way to achieve this could be preload const and check if the script path is null. So with this I could use the addon without major modifications in another project or I could put another timer script at the path for custom behaviour in a new project.

NOTE: I’m aware of load and check/load the path in ready:

const _timer_script_path = "res://resources/scripts/timer.gd"

func _ready():
	var timer = Timer.new()
	var script = load(_timer_script_path)
	if(script != null):
		timer .set_script(script)

But that method should be less optimal because is 1 load for EACH ready vs a SINGLE preload in a CONST at start of the game

Steps to reproduce: Create a script and try to preload an invalid resource with a const and run the game: const _script = preload("res://resources/scripts/timer.gd")

About this issue

Original URL
State: closed
Created 8 years ago
Reactions: 1
Comments: 17 (15 by maintainers)

Most upvoted comments

Crash (parse error actually) is fine, this is meant to always work. It would be worse if you mess up the name, it doesn t work and you dont realize you made a mistake.

On Mon, Nov 14, 2016 at 5:49 PM, Marc notifications@github.com wrote:

I agree a crash is not great. Your proposal should be fine if it doesn’t implies a runtime cost (besides initial load).

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reduz on Nov 14, 2016

Agree with Akien. Also I prefer a compile error than a successful compilation but a hidden bug.

neikeq on Nov 15, 2016

Well in theory with CONST the value should be executed 1 time for each script and with var the value should be executed for each instance of the script.

That’s true, but if it really, really matters, you can make a global singleton holding those variables and doing whatever you want with the resources just once.

bojidar-bg on Nov 16, 2016

preload expects a const String. If that const String points to an invalid path, that’s a bug from whoever wrote the string, and it’s normal that the program gives an error.

You can’t use preload to load resources dynamically, that’s load’s job, so it’s definitely what you want to use in your use case. It makes no sense to have preload return a null object if passed a bogus path. It should only return a null object if it was called on a valid path but an invalid resource (i.e. it couldn’t load the file because it’s not a resource Godot knows how to handle), not if the programmer made a typo.

akien-mga on Nov 15, 2016