Ruby Scripting

[kyonides]

The Lack of Interest into Fully Understanding a Programming Language

Many but many scripters around even to this day tend to misuse a feature of Ruby just because they found something similar in the default scripts. This has been true ever since RMXP came out as the first engine with some scripting capabilities and still returns every so often in VX Ace.

Defining a Class or Module

As I told you before, there is a simple way to create a class.

Code:

module MyModule
end

class MyClass
  include MyModule
end

And you can even include modules, not just one but many in a row! Just separate them by using commas.

So what's wrong with it?

Nothing. It has been correctly executed there. What I would like to criticize now is the lack of knowledge those scripters have shown over the years. It all begins with stuff like this.

Code:

class MyCommandWindow < Window_Selectable
end

Here many people fall in a trap that won't normally cause any issues except when they do it once again!
Yes, they repeat the same declaration over and over again every single time they define what we call the Parent Class or Super Class.

What it means is that MyCommandWindow is the Child Class of Window_Selectable, making it a window with menu features preincluded by default, even if they had been created in Window_Selectable only. And guess what? Window_Selectable class is a Child Class of Window_Base and the latter is the Child Class of Window!

As you can see the list can go way beyond your imagination, really it does.

But why do they keep repeating the same mistake over and over again?

That's because they lack some insight of Ruby inner workings like the C side of Ruby code. Yeah, Ruby is run on C functions. Every single Ruby Object is a special C struct.

C struct

What is a C struct?

Well, it's like a precursor of a C++ or Ruby class, initially only found in C but it spread to C++ as well. I can't talk about non C related languages so...

It pretty much has the same features as Ruby variables for you can easily access copies of your defined struct and its values in a similar fashion than Ruby, yes, with dots included. The difference is that they can also become pointers with its own connector instead of Values a la Ruby. Pointers are just memory references or addresses to a very specific point in, well, memory or RAM, that they have reserved for its own use. It is a small load of data to be passed to another struct pointer or any C function as an argument aka parameter.

The way I'll explain this issue is the following: declaring the class or module serves 2 main purposes.

1. Define the class or module and its parent class or module (as in a module nested inside another module). Do this once if they do have a parent class.
   
2. Reopen the class or module. That's it!
   

Ruby isn't like Java. The latter made it overly complicated to extend certain basic features like printing stuff on a shell or console.

Ruby just has OPEN CLASSES!

That's a nice feature that lets us add as much stuff as deemed necessary and alias (keep a reference to a preexisting method) a given method at will.

Downside: It might allow many people to rely on monkeypatching default classes as a way not to create child classes or delegate them to custom classes.

In CRuby you would use a function called rb_define_class("MyClass", rb_cObject) instead. Modules don't need a second parameter: rb_define_module("MyModule").

Internally it's used to determine if a class exists. Otherwise, it'll look for functions like rb_obj_alloc and stuff like rb_class_new and even an initializer., which can be your very own custom function or call your Ruby initialize method. A Ruby side initialize definition will certainly overwrite a C side one.

So whenever you repeat the whole statement, you keep telling the Ruby system that it should now check the parent class once again!

Why on earth!? It kept it in memory and won't forget it as long as the program is running. Thus, it makes no sense to insist on declaring that there.

And what comes next is especially directed at newcomers and slightly experienced scripters: stop doing it or you might end up making a mistake like declaring the wrong parent class!

This issue is similar to another one that keeps showing up in newcomers' codes, the excess of checks by calling too many if or unless or case statements to get to a single point where they simply need to change a variable's value, especially common whenever they need to toggle switches.


That topic might be something that should be handled in a separate post...

Happy Class Declarations!