Ruby Tips

Shuffle a word

The same technique to shuffle an array of numbers can be used to shuffle words. This is great if you want to scramble words, as in creating anagram puzzles.

<geshi lang="ruby"> 'anagram'.split(//).shuffle.join => "gnaarma" </geshi>

Shuffle a list of numbers

<geshi lang="ruby"> (1..14).to_a.sort { rand } => [14, 8, 1, 9, 3, 10, 5, 11, 7, 12, 4, 13, 2, 6]

1. or

(1..14).to_a.shuffle => [2, 5, 8, 12, 4, 3, 6, 13, 7, 11, 10, 1, 9, 14] </geshi>

Rename files

<geshi lang="bash"> for f in `ls`; do mv -u $f $(ruby -e "puts '$f'.gsub('14','13')"); done </geshi>

Check CLASSPATH

<geshi lang="ruby">

1. !/bin/env ruby
3. Checks to make sure all the entries on the classpath are valid

1. We only want to emit color codes if we're outputting to a terminal. If this is getting piped into grep or less, we'll ignore these

red=STDOUT.isatty ? "\e[1;31m" :"" normal=STDOUT.isatty ? "\e[0;0m" : ""

cp = ENV['CLASSPATH']

if cp == nil then

 STDERR.puts "No CLASSPATH set"
 exit 1

else

 # We'll assume a Windows CP.  We could do something ticky, but we have to be very tricky, because we're probably in Cygwin
 cp.split(';').each do |file|
   if !File.readable?(file) then
     STDERR.puts "Warning: Classpath file #{red}#{file}#{normal} can't be read"
   end
 end

end </geshi>

nextPrime

Short script to return the next prime number. <geshi lang="ruby">

1. !/bin/env ruby

def isPrime(n)

 prime = true
 3.step(Math::sqrt(n), 2) do |i|
   if (n % i == 0) then
     prime = false
     break
   end
 end
 if (( n%2 !=0 && prime && n > 2) || n == 2) then
   return true
 else
   return false
 end

end

i = ARGV[0].to_i

while !isPrime(i)

 i += 1

end

puts i </geshi>

Tab Completion in IRb

Add this to your .irbrc.

<geshi lang="ruby">

require 'irb/completion'
ARGV.concat [ "--readline", "--prompt-mode", "simple" ]

</geshi>

Thanks [why].

Ruby Patch to Zip

A script to take an Eclipse generated patch file, and zip every file which is referenced in the patch.

Ruby gems on Cygwin

aka how to fix ruby: no such file to load -- ubygem (LoadError) or /usr/bin/ruby: no such file to load -- ubygems (LoadError) <geshi lang="bash"> $ unset RUBYOPT $ cd /tmp/ $ wget http://rubyforge.org/frs/download.php/20989/rubygems-0.9.4.tgz $ tar -zxf rubygems-0.9.4.tgz $ cd rubygems-0.9.4 $ ruby setup.rb </geshi>

Ruby Yaml to Enum

Generate Java 1.5 enums from a YAML file

Ruby detab

A script for removing tabs from source files

Error Messages

• uninitialized constant PStore
• nonexistent sybase adapter

irb

Setup tab completion and history here: http://wiki.rubygarden.org/Ruby/page/show/Irb/TipsAndTricks

Escape invalid XML characters.

This is useful for running stuff through before posting it to the wiki.

echo "<a href=\"foo\">" | ruby -pe 'gsub!(/\&/, "&"); gsub!(/"/, """); gsub!(/</, "<"); gsub!(/>/, ">"); '
&lt;a href=&quot;foo&quot;&gt;