nothing is being added >_> Options

[Adrien.]

I might be doing this wrong but:

CODE

class SomeClass

      attr_reader :elements

      def initialize
      end

     def create
         @elements = Array.new
     end

    def add(object)
         @elements.push(object)
         return @elements
    end

   def size
        return  @elements.size
   end

end

someObject = SomeClass.new
someObject.create #works
someObject.add("String") #never adds
someObject.size #nil

#why is it never adding?

[Turkwise]

Looks simple enough...but it does seem to have some unnecessary layers of complication. Why not take out the create method and place its contents in initialize?

CODE

class SomeClass

      attr_reader :elements

      def initialize
         @elements = Array.new
      end

    def add(object)
         @elements.push(object)
         return @elements
    end

   def size
        return  @elements.size
   end

end

someObject = SomeClass.new
someObject.add("String") #never adds
someObject.size #nil

[Adrien.]

because there is create() and create(size) one states create while the other creates one of a fixed size.

How ever that does NOT answer my question of WHY nothing is being added.

[Night5h4d3]

How are you checking to see if the text is being added? It's working for me if I put print(someObject.size)
It's giving me 1.

[Adrien.]

This is my whole script. I didn't want to post it because 1) I am still learning the fundamentals of ruby syntax. I understand ruby as a whole in terms of OOP and its related concepts. How ever The syntax is my enemy and how things are done over such languages as java and 2) I didnt want to be made fun of >_>

CODE

class RGSSVector
  
  attr_reader :elements
  attr_reader :size
  
  def initialize
    #Does nothing but initialize the class to be used
    #with global variables such as $vector
  end
  
  def create(size)
    @size = size
    
    if @size <= 0
      raise "Error, vector size cannot be less then or equal to 0 elements in size."
    elsif @size != 0
      @elements = Array.new(@size)
      return @elements
    elsif @size == 0
      @elements = Array.new
      return @elements
    end
  end
  
  def create()
    @elements = Array.new
  end
  
  def clearVector
    if @size != 0
      @size = 0
    else
      @elements = Array.new
      return @elements
    end
  end
  
  def sizeOfVector
    if @elements.empty? != true
      return @elements.size
    end
  end
  
  def add(object)
    if @size != 0
      for @size in @elements
        if @size < @elements
          @elements.push(object)
          return @elements
        end
      end
    else
      @elements.push(object)
      return @elements
    end
  end
  
  def remove(object)
    if @size != 0
      for @size in @elements
        if @elements.index(object) != nil
          @elements.delete(object)
          return @elements
        end
      end
    elsif @elements.empty? != true
      @elements.delete(object)
      return @elements
    end
  end
  
  def isEmpty?
    return @elements.empty?
  end
  
end

This is why initialize is never used.

Add never add in this code. (for loops in ruby are also giving me a hard time when I am so use to doing for (int i = 0; i<something; i++){})


Thanks for your help

[Night5h4d3]

ah, I see, well, no one's going to fault you for learning RGSS/2; a couple things I'd like to throw off the bat, if you're gonna attribute size and elements, be sure to initialize them (in the def initialize, put: @elements =[], @size = 0) because all variables start out as nil, and you have bits of code where you are checking only if @size is <= 0. also, with your def create(size) and def create() you can compound those into:

CODE

def create(size=nil)
end

This way saves coding and achieves the same result. also, when specifying a new variable, you dont need to define it by it's type like in C++, so instead of @ary = Array.new you can put @ary = []


and regarding for loops, yeah, they can be confusing in comparison to C++/Java's way, but if you liken it to javascript's for each loop, it might make a little more sense.

edit- just checked it, if you put:

CODE

    @size = 0
    @elements = []

In def initialize, that should fix it, and you can leave the rest as is without issues.

[Adrien.]

I cannot compound them because unlike other languages like actionscript you cannot have "optional parameters" in ruby. so I have one blank that states create an array, and one with a parameters that says create an array of this size.

are my for loops correct?

Also is this code, or can we explain why this code, is not adding anything to the array?

ok will try this

also can you explain how to create a global variable INSIDE THIS CLASS to be used across other scripts?

also doing def create(size=nil) messes up the if statement of if @size <= 0 do this. it throws a no method error on <= should it be in this case !=0? the reason for the check is if the user enters a size we all know vectors of fixed sizes cannot be 0 or less, or other wise how will you store elements

thats why I had two create statements

Another thing:

when I use this code as:

vector = RGSSVector.new
vector.create()
vector.add("String")
print vector.sizeOfVector


I get nil so theres nothing in the array

one last thing, both create methods have been changed to createVectorOfSize(size) and createVector() because ruby does not support method over loading >_>

This post has been edited by Adrien.: Sep 1 2011, 11:26 AM

[Night5h4d3]

Ruby does allow optional parameters, like I showed, you can do def optionalArg(argument=<defaultvaluehere>) you just need to check if argument == <defaultvaluehere> for example:

CODE

  def create(size=nil)
    if size == nil
        @elements = []
    return @elements
    elsif size <= 0
        raise "Error, vector size cannot be less then or equal to 0 elements in size."
  else
    @elements = Array.new(size)
    return @elements
  end
end

edit- all you need to do is have it catch the nil first, like shown above

2) To me, it looks like @size represents the size of @elements, which you dont need to do, you can put @elements.size or .length to get the size of @elements, but other than that, I guess your for loops are fine.

3) The code wasnt pushing to the array because in the def add you have the comparison:
if @size != 0
nil != 0 and thus that if is entered, then the for loop runs basically like:
for (size = nil; size<elements; size++) which doesnt itterate because nil and nil already match up (elements is also nil at the beginning)
and so its skipping the push process.
(I hope this is all making sense)

4) basically, if you specify a global variable ($<namehere>) it's accessable from anywhere; all you'd need to do would be to specify it in the scope you need it.

also, it would seem that @size is unnecessary, because of the fact that you can use @elements.size or .length

edit - ruby doesnt allow overloading, no, instead it uses polymorphism, and default values, like stated above.

[Adrien.]

@Size is used to set the size of the array. so if you want you can have a vector of any size through not setting the size or you can have a size specified and the vector will only hold that many elements. so:

if nil, then create a array which will hold as many as possible elements, if size = 5 then create an array capable of holding only 5 elements. thats my logic behind it. One subject i struggled heavily on in school was the idea of polymorphism >_> so please be paitent if I tend to ask question I should know or seem dumb.

I see that ruby has a vector class and its largley array based - hence my implementation here. What i see they do is create @element = []. They do not set a size, I was planning to set that size by stating the size you enter is as many elements as you can hold. .size is used to say how many elements are in the vector. because, as stated before, the vector class is largley array based I can use array based methods inside my methods to gather data.

in response to number 3, so by recreating the create statement as you stated, the add should now work?

in response to number 4, if I were to say (at the top of this script out side the class) $Vector = RGSSVector.new and then call $Vector.create I get the error undefined method. Thats why I am strugelling with global variables because I do not understand where I need to initalize a global variable to avoid this error

Other responses

-> Whats the difference between polymophism and method overloading and how does it make for better/or worse programming in ruby?

When googleing how to do optional parameters in ruby I got a lot of forums and blog posts stating that ruby does not allow optional parameters but that there was a work around with using hash tags:

CODE

def method(required, required, option={})
   options { :option1 => false}
   option = options.merge(option)
end

My hash tag usage might be a bit off in this example but i hope you get the main idea.

I did not know you could go method (value=nil) (note: you can also do this in action script and it just clicked to me >_>)

Other

With create(size=nil)

if I do vector.create and not pass anything in then I get wrong number of arguments, (0 for 1). I thought it should default to nil?

also in my add function (when I pass in 1 to create it works) on the second if I am getting the error no method error for '<' when comparing if the size I set for the array is less the elements in the array, since I set the array size to 1 should this be <=, if so that poses the problem of if I have 5 elements in an array that can hold 5 elements, and i push one more it will now contain 6 elements.....(note: I still get no method error on <=)

Thanks for your help. If I ever get this working I will credit you in the script

[Night5h4d3]

1) @elements.size is dynamic in comparison to @size, you can only set @size when you're creating. if you're pushing values to @elements, the size will become larger than @size eventually, then you have issues; which is why you shouldnt use @size.

2) no, rewriting 'create' will not be enough, you need to set force @size to an actual value, or omit it, or make the if statement that surrounds the for loop have a condition for if @size == nil

3) like I mentioned in your other topic, you dont use global variables for self, or reflection. if you wanted to run def create from within the vector class you would use self.create, or, you'd initalize the vector class AS the global variable ($myvector = Vector.new) and then call create from the variable ($myvector.create). the reason why you get the error is because you're calling def create before it was interpreted

4) they're generally the same, with a few differences, polymorphism includes method overloading. but polymorphism is actually irrelevent in this case, I was just explaining one of the ways of 'overloading' arguments in Ruby

5) ruby does allow optional parameters, see Window_Selectable under initialize, spacing is default to 32

6) ruby does allow nil as default I just double checked it again to make sure. check to make sure you're using one def and not 2, and that you wrote it right.

7) This is the result of using @size separate from @elements.size (refer back to 1)

Hope that helps!

[Adrien.]

It does but it leave me with more question >_> I hate asking questions. >_>

1) If I am to remove @size all together how will I Set the size of the array to that of which the user sepcifies? for example user wants a vector to contain 5 elements and only 5 elements. How would this get done if @size is to be removed? as you see when you se the size I am doing @elements = Array.new(@size) according to the ruby doc for arrays Array.new(size) allows you to set the size of the array to contain that many elements.

2) for global variables then the user of this script will have to create their own global variable? as I cannot do so here? I was so hoping to stop them from having to go vector = RGSSVector.new vector.create and so on. Is it wise in the documentation to state $Vector.create does this that and those? or should I just say the create method....

This is my create statement that throws an argument error (there is only ONE create statement as of now)

CODE

  def create(size=nil)
    @size = size
    
    if @size == nil
       @elements = []
       return @elements
    elsif @size != nil
        @elements = Array.new(@size) #I set the size of the array to be allowed to hold this many elements
    elsif @size <= 0
        raise "Error, vector size cannot be less then or equal to 0
               elements in size."
        return @elements
    end
  end

vector = RGSSSVector.new
vector.create #upon running I get the argument error

to go back quickly to your "you don't need @size" I hope this code, explains why I need @size. @element.size will check the size of the array, which is fine. But if the user specified I want this array to only have 5 elements and no more....@element.size will not help. If I understand you correctly. Could you maybe post an example of how you would do this with out @size and make sure the user could still pass in a specified size for the vector or pass in nothing and just let the vector grow to what ever size they wish for what ever data they are pushing in? (which can be dangerous)

It really does help, I am better understanding ruby concepts as a whole. Its the syntax I am having issues with and some logic. but these are just growing pains of a new language

[Night5h4d3]

Well, I cant think of any other way to do this so.. if I were to make this script, and kept in @size, then here's what I would do:

CODE

class RGSSVector
  attr_reader :elements
  attr_reader :size
  def initialize
    #Does nothing but initialize the class to be used
    #with global variables such as $vector
    @elements = []
    @size = nil
  end
  
  def create(size=nil)
    @size = size
    if @size == nil
      return @elements
    elsif @size <= 0
      raise "Error, vector size cannot be less then or equal to 0 elements in size."
    else
      @elements = Array.new(size)
      return @elements
    end
  end
  
  def clearVector
    self.create
  end
  
  def sizeOfVector
    if @elements.empty? != true
      return @elements.size
    end
  end
  
  def add(object)
    if @elements.size == @size and @size != nil
      @elements[@elements.nitems] = object
      return @elements
    else
      @elements.push(object)
      return @elements
    end
  end
  
  def remove(object)
    if @elements.include?(object)
      @elements.delete(object)
      return @elements
    end
  end
  
  def isEmpty?
    return @elements.empty?
  end
end

if you have any questions, then I'd be happy to answer them.
also, if you wanted to save scripters from using $Vectorthing = VectorClass.new you have 2 options, create it as a module instead, OR put $Vectorthing = VectorClass.new in main.

edit- a module is actually FAR more well suited for what it seems you're trying to accomplish with this snippet.

[Adrien.]

Would it be ok if I based my script off of this one? assuming I gave you credit (full - for such methods) - not copy and paste but use the ideas here?

Your help in this matter has been greatly appreciated. I can fully understand whats happening here.

as for the module would it be:

CODE

module CALL

$vector = RGSSVector.new

end

class


def initialize

include CALL #i think?

@size = 0
@elements = []

end

...code

end

[Night5h4d3]

you'd rename class RGSSVector to module RGSSVector; then you'd add self. before every def name(ie: def self.add). then if you wanted to add/remove/whatever to your elements array you'd be like:

CODE

RGSSVector.add(object)

And you wouldnt need the global variable

[Adrien.]

Ill have to do some reading up on modules as thats a whole new concept to me >_>

would I still need initialize? would it be def self.initialize

This post has been edited by Adrien.: Sep 1 2011, 02:31 PM

[Night5h4d3]

You wouldn't need to initialize it

[Adrien.]

sweet jesus. Like I said I need to read up on modules but this has all very much helped me. As i go back to my last (possibly last) question. the usage or baseage of my code off yours, whats your rules for that if you see my script ever published and are like "hey....I wrote one or more of those methods...." is credit enough or....?

[Night5h4d3]

Credit is fine (IE: special thanks: night5h4d3 or something), I only charge if people want to use my scripts commercially, if that's what you mean.

[Adrien.]

no no this is purly open source and for free. If I release this script to the comunity I will create a special thanks section for you you in that thread post, blog post, google code section. For now I will credit your name in the documentation

Problem:


if I do:

CODE

module RgssVector
  
  attr_reader :elements
  protected :elements
  
  @size = nil
  @elements = []
  
  def self.create(size=nil)
    @size = size
    
    if size == nil
      return @elements
    elsif size != nil
      return @elements = Array.new(@size)
    elsif size <= 0
      raise "Vector Error -> Size of vector cannot be 0!"
    end
  end
end

and then do RGSSVector.create(5)

I get:

NameError ocurred while running script Uninitialized constant Game_Interpreter::RGSSVector

I am pretty sure I am doing something wrong


This post has been edited by Adrien.: Sep 1 2011, 04:03 PM