# Creating file names with string

**URL:** <https://www.ruby-forum.com/t/creating-file-names-with-string/98698>\
**Category:** Ruby\
**Created:** [January 30, 2006, 6:32am UTC](https://www.ruby-forum.com/t/creating-file-names-with-string/98698 "2006-01-30T06:32:59Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jmaenpaa](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de053/32.png) [@jmaenpaa](https://www.ruby-forum.com/u/jmaenpaa)\
**Post date:** [January 30, 2006, 6:32am UTC](https://www.ruby-forum.com/t/creating-file-names-with-string/98698/1 "2006-01-30T06:32:59Z")

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Hey chaps,

# A script to ask a user for a string and use it to grep through a

file. My first version works.

# It was suggested to turn the constants into objects whilst chatting on

ruby-lang. Please compare the two methods  
(excuse the pun). What’s wrong with using constants and what am I doing  
wrong in my OO version?

#first version using constants

DataDir= “/home/jayeola/bin/acid/data/lookups/”  
DataFile = “lookup\_assetype.txt”  
Lookup = File.join(DataDir, DataFile)

def usage  
screen = “type some letters in the word”  
end

def grabber

# grab first couple letters and grep thru file

xx = gets.chomp!  
File.open("#{Lookup}") do |test|  
test.each do |line|  
puts line if line =~ /#{xx}/  
end  
end  
end

puts usage  
grabber

# This doesn’t work. The “object” way…

def usage  
screen = “type a few letters containing the word”  
end

i = Greppa.new("{@datadir}", “{@datafile}”)  
i.inspect  
puts usage  
puts lookup

# filelocations

class Greppa  
def initialize(datadir, datafile )  
@datadir= “/home/jayeola/bin/acid/data/lookups/”  
@datafile = “lookup\_assetype.txt”  
@lookup = File.join(@datadir, @datafile)  
end  
end

def grabber  
lookup = File.join("{@datadir}", “{@datafile}”)

# grab first couple letters and grep thru file

xx = gets.chomp!  
File.open("#{lookup}") do |test|  
test.each do |line|  
puts line if line =~ /#{xx}/  
end  
end  
end

# 

i = Greppa.new("{@datadir}", “{@datafile}”)  
i.inspect  
puts usage  
puts lookup

---

<div class="post-metadata">

**Author:** ![jmaenpaa](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de053/32.png) [@jmaenpaa](https://www.ruby-forum.com/u/jmaenpaa)\
**Post date:** [January 30, 2006, 9:01am UTC](https://www.ruby-forum.com/t/creating-file-names-with-string/98698/2 "2006-01-30T09:01:43Z")

</div>

On 1/29/06, John M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> Hey chaps,

Hi John,

> (excuse the pun). What’s wrong with using constants and what am I doing  
> wrong in my OO version?

Well the first thing that struck me is that hardcoding the path  
into the program you is not good, it would be a more useful  
program if you could specify which file to search on the  
command line as well as the regex in question.  
I’ll leave implementing that method up to you.

I’m just learning myself, but I touched up your OO version  
but kept your logic mostly intact.  
Enjoy.

class Greppa  
def initialize(file)  
@f=file  
end

def usage  
print "(Greppa)Enter a regex:\> "  
end

def grabber  
usage  
xx = gets.chomp!  
File.open(@f, ‘r’) do |test|  
test.each do |line|  
puts line if line =~ /#{xx}/  
end  
end  
end  
end

#Rather than hardcoding lets make a new method that  
#asks the user for the `data` file

data = “/home/flubber/greppa.rb”

i = Greppa.new(data)  
i.grabber