Learning Regex con't (xxxxxxx-xxxx where x's are digits)

This one (regex) didn't take me as long to figure out given all that I read about regular expressions.

As part of my homework for Learning Ruby the Hard Way, I'm still working on my editor that takes 8 pieces of information and inserts it all into a tab delimited format .txt file.  The second column needs to be in the format of xxxxxxx-xxxx where the x's are digits and the hyphen needs to be included.  This is an account id in the system I'm working with where I'm going to eventually create a script to combine rows from files a 3rd party agency is giving to us.

Back to the editor, I created a regex to only accept an account id that has 7 digits, a hyphen followed by 4 more digits.  This one was easy compared to the online tutorials I was reading over.  Just inserting the regex here so I'll have it for future reference.

/^\d{7}\-\d{4}$/

Maybe by the time I'm finished with the 2 projects I want to complete, I'll have a cook book of regex's.

Learning Regex (file name with .txt extension)

I've gone through 6-7 web pages and 2 tutorials.  I did an initial search for a regex for a file name.  I didn't search but a minute or two then decided I need to learn a little more about regular expressions than just how to come up with one to recognize a file name.

After reading through a lot of documentation, I believe I came up with what I needed but first a little background.

I'm on lesson 36 of Learn Ruby the Hard Way.  I'm not making a game like the home suggests to.  Instead, I'm making a script that will ask for eight pieces of information and it will create a tab delimited file with each piece of information.  I'm giving the user the option to name the file.  The requirements will be that it must only contain letters (upper/lower case), digits, a hyphen and an underscore character and the file extension must end with a ".txt" (without the double quotes).  If the user types in anything else, it won't be accepted.

So I'm still at the beginning of creating this script and had to stop for a few days to learn how to put together regular expressions.  This is what I have so far for an acceptable file name.

I chose this type of project over creating a game because I need to ultimately create a script that parses a tab delimited file and combines rows/records based on values in 2 columns.  That will be my next project.

Here's the regex that I came up with to accept a file name with the above mentioned requirements.

/^[^\W+]\w+\-?(.txt$)/

I'm always open for suggestions on simplifying my code. I'm in no way an expert but the above expression works for what I need it for.  I'll be studying regular expressions in more depth as I continue on with my projects.

User input stored as a string ($stdin.gets.chomp)

Following along with LRtHW on exercise 31 and I was wondering why the author was testing the user input as a string.

There was an exercise that covered gets.chomp but I never thought about it returning a string.  Then I found this documentation...

http://www.ruby-doc.org/docs/Tutorial/part_02/user_input.html

I was assuming that it would take the user input as is but the above link states...

1. chomp is a string method (String#chomp).
2. gets returns (gives you back) a string.

When I changed the code in the exercise from...

puts "You enter a dark room with two doors. Do you go through door #1 or door #2?"

print "> "

door = $stdin.gets.chomp

if door == "1"

  puts "There's a giant bear here eating cheese cake. What do you do?"

end

...to...

puts "You enter a dark room with two doors. Do you go through door #1 or door #2?"

print "> "

door = $stdin.gets.chomp.to_i

if door == 1

  puts "There's a giant bear here eating cheese cake. What do you do?"

end

..it worked as expected.

Ruby naming

Following along with the online LRTHW exercises and lesson 25. I copied the code as it was stated from the web page. Well, I typed it in manually rather than doing a copy and paste. Just to take a shortcut to type it in as fast as possible, I didn't capitalize the module name and I got the following error...

2.1.3 :001 > require "./ex25.rb"

SyntaxError: /home/.../ruby/ex25.rb:1: class/module name must be CONSTANT

from /home/.../.rvm/rubies/ruby-2.1.3/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:54:in `require'

from /home/.../.rvm/rubies/ruby-2.1.3/lib/ruby/site_ruby/2.1.0/rubygems/core_ext/kernel_require.rb:54:in `require'

from (irb):1

from /home/.../.rvm/rubies/ruby-2.1.3/bin/irb:11:in `<main>'

After going back and capitalizing the module name, function names and references to the functions, I was able to get it run without error.

2.1.3 :001 > require "./ex25.rb"

 => true 

Found official documentation that discusses naming.  The exercise didn't cover the topic of naming...

http://www.ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/constants.html