How to implement custom binary resource file load function in ResourceFormatLoader?

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:bust_in_silhouette: Asked By Andrew Wilkes

Hello. I want to use a custom file extension for .res files but cannot work out how to load the file in the ResourceFormatLoader.

extends ResourceFormatLoader
class_name CircFormatLoader

func get_recognized_extensions() -> PoolStringArray:
	return PoolStringArray(["circ"])

func get_resource_type(_path: String) -> String:
	return "Resource"

func handles_type(typename: String) -> bool:
	return typename == "Resource" 

func load(path: String, _original_path: String):
	var file = File.new()
	if file.file_exists(path):
		file.open(path, File.READ)
# Cannot read the binary res file. End up with null return value
		var res = file.get_var()
		file.close()
		return res
	else:
		return ERR_FILE_NOT_FOUND