Placeholder resources

[maksloboda]

Lets say that I want to load some resource on demand.
Common pattern goes like this:

func on_some_event():
	print("Resource used")
	var icon : Resource = load("res://icon.png")
	print(icon)

Resource is loaded on demand but we've got a problem, what if the resource moves? In that case our code becomes broken. As a cherry on top this resource is not marked as a dependency, so it can be deleted/moved by an unsuspecting colleague.

Right, but that's what we have export for right?
Lets inspect this code:

# Specified in the editor as "res://icon.png"
export var icon : Resource = null

func on_some_event():
	print("Resource used")
	print(icon)

Now we have code that tracks the resource path but in return dependency gets loaded when the scene gets loaded.

Okay, but so what? When not using load even small projects take a long time to start the game because they need to load nearly everything at once. Level select would have a reference to every level which has a reference to every object and so on.

There exists a feature, that i don't hear about often, called "Load as placeholder". This feature works only for scenes and does almost what i need.
It is possible to create a scene that has an object that contains a Resource. Example:

But because of the inner mechanics of the child scenes it would require to create and setup separate scene for each resource.

TLDR:
Current resource handling is limited and leads to tradeoff between:

1. Unreliable code
2. Long load times/Excessive RAM use
3. Using weird and hard to setup constructions for a simple action.

Proposed solutions:

1. Ability to do something like export(String, FILE) that updates dependencies of the scene and tracks specified resource.
2. class ProxyResource that has one method Resource load() and allows to create such indirect references.