Ruby Newbie...Classes and Objects, oh my!

Ruby
1

I’m very new to Ruby and I’m trying to create a program that will take
one text file and dump each line into an array. Then I take a second
file and dump that into a string. Then I insert the string into the
array. The code for these pieces work. However, for flexibility I want/
need to be able to use OO methods and that is where I seem to hit a
wall. Not sure what I am supposed to do or how to call it. Below is my
code, any input you may have would be greatly appreciated!!!

###############################################################

class XMLProcessing
def initialize(array_file, string_file, output_file)
@array_file = array_file
@string_file = string_file
@output_file = output_file
end

def lines_to_array
# Dump each line from text file into array
File.open(@array_file).each do |line|
my_array << line
end
end

def file_to_string
# Create string from text file
@my_string_file = File.open(@string_file)
my_string = @my_string_file.read
end

def string_into_array
# Insert string into array
my_array.insert((my_array.length - 1), my_string)
end

def new_array_to_file
# Dump the array to a text file
newFile = File.new(@output_file, “w+”)
my_array.each { |element| newFile.puts element }
print 'New file created: ’ + (@output_file)
end
end

stat_xml = XMLProcessing.new(“Stat.Template.xml”, “Seg.Template.xml”,
“stat.xml.txt”)

###############################################################

2

On Mon, May 24, 2010 at 4:30 PM, fuglyducky [email protected]
wrote:

class XMLProcessing
def initialize(array_file, string_file, output_file)
@array_file = array_file
@string_file = string_file
@output_file = output_file
end

   def lines_to_array
           # Dump each line from text file into array
           File.open(@array_file).each do |line|
                   my_array << line

This is a local variable, uninitialized for that matter
try
@my_array = []
File.open…
@my_array << line
end

However, you could also simply do a
@my_array = File.readlines( @array_file ).map( &:chomp )
or the more explicit (and in Rubies < 1.9 necessary )
@my_array = File.readlines( @array_file ).map{ |line| line.chomp }

           end
   end

   def file_to_string
           # Create string from text file
           @my_string_file = File.open(@string_file)
           my_string = @my_string_file.read

Same here
@my_string = …

   end

   def string_into_array
           # Insert string into array
           my_array.insert((my_array.length - 1), my_string)

and here too
@my_array

   end

   def new_array_to_file
           # Dump the array to a text file
           newFile = File.new(@output_file, "w+")
           my_array.each { |element| newFile.puts element }

change here too
@my_array

           print 'New file created: ' + (@output_file)
   end

end

stat_xml = XMLProcessing.new(“Stat.Template.xml”, “Seg.Template.xml”,
“stat.xml.txt”)

Now just call the methods you want to execute on stat_xml as e.g.
stat_xml.file_to_string
…
…

I do not think your design is ideal, calling all those external method
calls for intermediate computations(1), but for a beginner it is
pretty nicely structured code.

HTH
R.

(1) But there might be reasons invisible to YHS.

3

On May 24, 8:57 am, Robert D. [email protected] wrote:

                   my_array << line

or the more explicit (and in Rubies < 1.9 necessary )

           # Dump the array to a text file

stat_xml = XMLProcessing.new(“Stat.Template.xml”, “Seg.Template.xml”,

The best way to predict the future is to invent it.
– Alan Kay

Wow…thanks for the response!!! I’m not a programmer for a developer
by any means. I’m a tester that needed a quick (and hopefully not too
dirty) way of creating the files I need. The reason I wanted to call
all of the submethods was because I need to be able to create a random
number of some of the individual files before I dump them into the
array. I thought that in the main body of the code I would script it
out to call that particular method. This is all pretty new to me…is
that bad form?

4

On 24.05.2010 18:42, fuglyducky wrote:

class XMLProcessing
try
def file_to_string
and here too
end
pretty nicely structured code.
The best way to predict the future is to invent it.
– Alan Kay

Wow…thanks for the response!!! I’m not a programmer for a developer
by any means. I’m a tester that needed a quick (and hopefully not too
dirty) way of creating the files I need. The reason I wanted to call
all of the submethods was because I need to be able to create a random
number of some of the individual files before I dump them into the
array. I thought that in the main body of the code I would script it
out to call that particular method. This is all pretty new to me…is
that bad form?

Hm, difficult where to start. If I read your code properly you have
three file names as inputs and want to create the concatenation of the
two first files as the third file. On shell level you could simply do

$ cat f1 f2 > f3

There is no Ruby programming needed. Even if you want to do that in
Ruby, there is not really a need for new classes you can do this in just
a few lines in a function.

Concat all files given as second, third etc. argument

to a file with name provided as first argument

def file_concat(out, *in)
File.open out, “w” do |io|
in.each do |file_in|
File.foreach file_in do |line|
io.puts line
end
end
end
end

file_concat(“stat.xml.txt”, “Stat.Template.xml”, “Seg.Template.xml”)

This code has the advantage over your solution with the Array that it
easily processes arbitrarily large files because you do not have to hold
the complete output file in memory.

A new class of your own is probably only worthwhile if you have to do
more complex processing on the file’s content. Even if you create a
class you should do the processing like shown in the first example, i.e.
not hold the complete files in memory, e.g.

class XMLProcessing
def initialize(array_file, string_file, output_file)
@array_file = array_file
@string_file = string_file
@output_file = output_file
end

def process
File.open @output_file, “w” do |io|
[@array_file, @string_file].each do |file_in|
File.foreach file_in do |line|
io.puts line
end
end
end
end
end

Kind regards

robert

5

Not at all, small methods are considered good by many, I just had the
thought that you might call them in the initializer. As you did not
define accessors to the instance variables I did not see any reason to
keep the “intermediate” state between the method calls.

But again it is amazingly nice for a beginner. (I almost believe that
you are just humble)
Keep us updated about your progress :slight_smile:

Cheers
R.

6

On May 25, 12:40 am, Robert D. [email protected] wrote:

R.
Thank you both for the information! I was able to get it working with
your help. I think I may need to rethink my entire script (I’ll create
a new post for that one because it’s beyond my understanding of Ruby
(or any other language)…which is minimal.