Newbie needs help with first project


#1

I was told about Ruby several weeks ago and started my journey lol. I’ve
read several tutorials but reading the tutorials I still couldn’t grasp
most of it and I thought finding a project I wanted to work on and
just diving in might be the best bet.

I want to create a program that I can enter my game collection into.
Ideally I want it to have a simple gui so others can use it and input
their games as well.

Here’s the basic code I have I keep getting an error stating
uninitialized constant Game (NameError)

code:

class Games
def
initialize(title,platform,genre,rating,published_by,developed_by,year,condition)
@title=title
@platform=platform
@genre=genre
@rating=rating
@published_by=published_by
@developed_by=developed_by
@year=year
@condition=condition
end
end

class Games
def to_s
“Games:
#{@title}–#{@platform}–#{@genre}–#{@rating}–#{@published_by}–#(@developed_by)–#(@year)–#(@condition)”
end
end

game1=Game.new(“FireProReturns”,“Playstation_2”,“Sports”,“Teen”,“Agetec_Inc.”,“Very_Good”)
game1.to_s

Any help tips and etc on how to fix my problem and proceed will be
greatly appreciated.


#2

I think your problem is that the class is named ‘Games’ but you are
initializing it by calling Game.new. Try changing ‘Games’ in the class
definition to ‘Game’, it should work then.


#3

Stefan Codrescu wrote:

Is what I’m guessing you should have.
You can put both of the methods in the same class.
You forgot the ‘puts’ before the Games: in the to_s method

No, Daniel had it right. A class’s #to_s method is expected to return
a string, not print a string. If you want to print the string
representation of a Game object, you would use

game1 = Game.new(…)
puts game1.to_s


#4

Thanks for all the help. I appreciate it. just had a thought though.
continuing the way I’m doing it now all the games I enter will be lost
when I close the program right ?

is there a way i can code it so the user is asked for the
title,rating,condition and etc of a game. when they put it in is
stored in a file with the rest of the games they input.
then they can sort them or list them by rating,platform,or genre.


#5

On Sun, Mar 22, 2009 at 9:32 AM, Daniel D. removed_email_address@domain.invalid wrote:

uninitialized constant Game (NameError)
@rating=rating
end

class Game
def
initialize(title,platform,genre,rating,published_by,developed_by,year,condition)
@title=title
@platform=platform
@genre=genre
@rating=rating
@published_by=published_by
@developed_by=developed_by
@year=year
@condition=condition
end

def to_s
puts “Games:
#{@title}–#{@platform}–#{@genre}–#{@rating}–#{@published_by}–#{@developed_by}–#{@year}–#{@condition}”
end
end

game1=Game.new(“FireProReturns”,“Playstation_2”,“Sports”,“Teen”,
“Good”,“Agetec_Inc.”,“2000”,“Very_Good”)
game1.to_s

Is what I’m guessing you should have.
You can put both of the methods in the same class.
You forgot the ‘puts’ before the Games: in the to_s method
Also uh to print a variable you have to have #{var} not #(var)
and when you had the game1=Game.new you were missing two of your
arguments
hehe I just made them up.
And as Vikhyat said you needed to name the class Game for your
initialization to work or you can keep the class name Games but put the
other one to Games too.
Running the code above should give you

Games:
FireProReturns–Playstation_2–Sports–Teen–Good–Agetec_Inc.–2000–Very_Good


#6

You could eventually use YAML or XML to store your data and get it back
later the way you want.


#7

thanks for the example Stefan. it doesn’t seem to ask the user to
input the information though but I’ll be sitting down looking through
each line . great example to learn form so thanks for that.

Pierre , I’ve seen YAML mentioned else where but I haven’t been able
to find any good documentation or tutorials on how to use it with ruby.

Pierre P. wrote:

You could eventually use YAML or XML to store your data and get it back
later the way you want.


#8

Daniel D. wrote:

Pierre , I’ve seen YAML mentioned else where but I haven’t been able
to find any good documentation or tutorials on how to use it with ruby.

That’s syck!


#9

Yes there is a way to do that…

class Game
def
initialize(title,platform,genre,rating,published_by,developed_by,year,condition)
@title=title
@platform=platform
@genre=genre
@rating=rating
@published_by=published_by
@developed_by=developed_by
@year=year
@condition=condition
@my_file =
File.new("/Users/Stefan/Ruby/yourfileorthenameofthefileyouwanttocreate.txt",
‘a+’)
end

 def to_s
     puts "Games:

#{@title}–#{@platform}–#{@genre}–#{@rating}–#{@published_by}–#{@developed_by}–#{@year}–#{@condition}"
end
def savedata
@my_file.puts "Games:

#{@title}–#{@platform}–#{@genre}–#{@rating}–#{@published_by}–#{@developed_by}–#{@year}–#{@condition}"
end
def printdata
file =
File.open("/Users/Stefan/Ruby/yourfileorthenameofthefileyouwanttocreate.txt")
file.each {|info| print info}
end
end

game1=Game.new("
FireProReturns",“Playstation_2”,“Sports”,“Teen”,
“Good”,“Agetec_Inc.”,“2000”,“Very_Good”)
game1.to_s
game1.savedata
game1.printdata

the a+ means that it will create a new file and write to it or it will
add
on to the end of that file if it already exists.
and I also added a method that will print the file that you made.
also note that since the file is in the a+ mode if you run the program 5
times for example you will have five entries even if they are all the
same.


#10

Daniel D. removed_email_address@domain.invalid writes:

Pierre , I’ve seen YAML mentioned else where but I haven’t been able
to find any good documentation or tutorials on how to use it with ruby.

What’s wrong with “ri YAML” ?


#11

Daniel D. wrote:

Thanks for all the help. I appreciate it. just had a thought though.
continuing the way I’m doing it now all the games I enter will be lost
when I close the program right ?

Yep. In addition to the options already listed:

  • Marshal.dump and Marshal.load will store an arbitrary graph of Ruby
    objects (that is, the object plus all the objects it refers to) to an
    opaque binary file. Some objects cannot be Marshaled - e.g. File/IO
    objects, procs, and any object with singleton methods

  • There are plenty of libraries which will store your objects in a SQL
    database, the most popular being ActiveRecord, but there are many other
    options including Sequel and DataMapper.

In this case, you need not define attributes in your class at all,
because they are added at runtime based on the columns in the database.
That is,

ActiveRecord::Base.establish_connection(
… database connection params …
)
class Game < ActiveRecord::Base; end

is all you need to access a table called ‘games’.

Of course, sorting and searching are bread-and-butter to a SQL database.

HTH,

Brian.


#12

Alle Monday 23 March 2009, Eric J. ha scritto:

What’s wrong with “ri YAML” ?

In my opinion, it’s not very informative. True, it does have a (very
minimal)
example, but most of it is either very generic (the first part) or
mostly
suited for people who already know how YAML works (the second part).

As for tutorials on YAML and ruby, you can look at the YAML for ruby
cookbook
(http://www.yaml.org/YAML_for_ruby.html). I found it extremely useful
while
learning YAML. Also, YAML in Five Minutes
(http://yaml.kwiki.org/index.cgi?YamlInFiveMinutesMinuteOne), which is
mentioned in ri YAML, can be useful.

Stefano


#13

OH… If you want the user to enter something you can have something
like

puts “Enter the name of the game:”
@name = gets

and so on for each variable


#14

2009/3/24 Daniel D. removed_email_address@domain.invalid:

      @genre=genre
 @title = gets
 @genre.to_s
 @developed_by= gets
def to_s
  end

end

The pathname “C:\ruby\gamesdb.txt” should be
“C:\ruby\gamesdb.txt” or “C:/ruby/gamesdb.txt”

Regards,

Park H.


#15

thanks again . I’ll look into those links about YAML

here’s what I got so far. the input works correctly but I still can’t
get it to save the info that I input into a file

class Game
def
initialize(title,platform,genre,rating,published_by,developed_by,year,condition)
@title=title
@platform=platform
@genre=genre
@rating=rating
@published_by=published_by
@developed_by=developed_by
@year=year
@condition=condition
@my_file= File.new(“C:\ruby\gamesdb.txt”,‘a+’)
end

puts “Enter the name of the game:”
@title = gets
@title.to_s

puts “Enter the platform:”
@platform = gets
@platform.to_s

puts “Enter the genre:”
@genre = gets
@genre.to_s

puts “Enter Rating:”
@rating=gets
@rating.to_s

puts “Published by:”
@published_by = gets
@published_by.to_s

puts “Developed by:”
@developed_by= gets
@developed_by.to_s

puts “What Year was it released?:”
@year= gets
@year.to_s

puts “What condition is it in?:”
@condition= gets
@condition.to_s

def to_s
puts
“Games:#{@title}–#{@platform}–#{@genre}–#{@rating}–#{@published_by}–#{@developed_by}–#{@year}–#{@condition}”
end
def savedata
@my_file.puts
“Games:#{@title}–#{@platform}–#{@genre}–#{@rating}–#{@published_by}–#{@developed_by}–#{@year}–#{@condition}”
end
def printdata
file = File.open(“C:\ruby\gamesdb.txt”)
file.each {|info| print info}
end

end