• CommunityForum

  • Is it possible to change the value of an exported variable using code?


I have a node with two exported variables and the default value of "Num" is 0. I added this node to a scene.
When I change the value of "Num" to 2 in the inspector, the values of the export variables are permanently stored in the scene. My question is: Is it possible to change the value of the export variable using code?
Because currently when I change the value of the export variable "Num" to 3, when I go to another scene and return, the value of "Num" changes back to 2, which is not what I expected.
The reason I'm asking this question is because I want to use export variables to "store" the state of the trees in the map. For example, I have an export variable for the state of the trees (1 for spring, 2 for summer, 3 for fall, 4 for winter) so if the season changes, I can change the state of the trees and save the map so that I don't need to add additional logic to store the information.
Also, is it a bad idea to use export variables to store things?

  • Toxe replied to this.

    CrayonApe when I go to another scene and return

    What do you mean by going to another scene and returning?

    Do you have two different scene files that both have a node with this script attached? In that case those two exported variables are independent from each other.

        Toxe Scene A has this node which sets 'Num' value to 2 in editor, then I change it's value to 3 using code, Scene B doesn't have this node. When I go to scene B and return to scene A, the value of exported variable 'Num' in scene A becomes 2 again.

          Toxe Exported variables seems to be used as an "editable" tool rather than a persistent one, right? So I should never consider it as a way to "store" persist data.
          I feel confused because it offers an "editable" initial value.

          • Toxe replied to this.

              The question is what do you mean by "go to scene"? Switching to a different scene at runtime via change_scene_to_file or change_scene_to_packed? If that is the case all state of the previous scene is lost. Scene state is not persistent over scene changes. That has nothing to do with export. All (non-static) variables behave that way.

              If you need state to persist across scene changes use autoloads.

              CrayonApe Oh I think I understand.

              Right, your own exported properties are just like the properties that you see in the inspector from build-in classes like the transform of a Node2D or visible from a CanvasItem. Open your .tscn file in a text editor and you'll see that their values are stored in your scene files. So if you change them at runtime (like you would position of a Node2D) they won't get saved in your scene files.

              CrayonApe So I should never consider it as a way to "store" persist data.

              Correct.

                    Toxe Yeah, the "editable" and "persistent" nature of exported variables had me thinking in the wrong direction.
                    So if I want to keep my data "persistent" between scenes, I should use the autoload feature to save the global variables I want to track. And if I want to keep my data "persistent" between different game sessions, I should use local files(Json/ Resource/ Xml) to save the data. Right?

                    • Toxe replied to this.

                        CrayonApe So if I want to keep my data "persistent" between scenes, I should use the autoload feature to save the global variables I want to track.

                        There are multiple ways to do this. Global shared Node, Dictionary, some object or Resource, singleton...

                        CrayonApe And if I want to keep my data "persistent" between different game sessions, I should use local files(Json/ Resource/ Xml) to save the data. Right?

                        Right, saved somewhere in user://.