CODEWITHSUNDEEP
gmlgame-maker-studio-2
J E K
J E K

Reputation: 314

How do I require certain instance variables be provided at object creation?

Let's say I have a type of object in my game called oCharacter. All characters must have names, so I want to provide one when I construct the object. I can do that by using the _variables argument of instance_create_layer:

instance_create_layer(0, 0, "Instances", oCharacter, { name: "George" });

I could even make sure that I don't forget to do this by making a "constructor" function for characters and only instantiating them using that:

function character_create(_x, _y, _name) {
    return instance_create_layer(_x, _y, "Instances", oCharacter, { name: _name });
}

But this approach has two problems.

The first is that I or another developer might forget about this convention and instantiate a character directly using instance_create_layer, forgetting to pass a name and setting up a runtime error further down the road.

The second (related) issue is that Feather doesn't know about this convention, so my Feather window is full of error messages about references to instance variables that aren't declared in the Create event - but I don't see how I can declare these variables in the Create event, as I'm expecting their value to be provided by the creator.

Is there some way of doing this that addresses these issues?

Upvotes: 0

Views: 338

Answers (2)

Treasure Dev
Treasure Dev

Reputation: 588

Personally I would do two things for this.

  1. Create development standards for the team and put them in something like a Word document, wiki page, onenote, whatever makes the most sense for your team.

  2. I would use a function to create the instance of the object (like you're doing there), and have some simple validation checks inside of the create event itself that will cancel it's creation (something like a guard clause) and output a debug message with a reminder.

It's not the most elegant solution but that should do the trick (assuming you haven't found something else by now haha)

Upvotes: 0

Steven
Steven

Reputation: 2122

The first problem is just about setting rules about the code conventions within your team, if your team does not know about these conventions you want them to follow, then you should tell it them in a meeting.

For the second problem: Maybe you could create an empty/nullable variable in the Create Event? I'm afraid I'm not familiar with Feather

Upvotes: 1

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