Ruby
From MohidWiki
Ruby is (said to be) a great language. People say that programming is fun again. Everything in Ruby is an object. Strings, floats, integers, regexps, arrays are all objects, and all have their methods and fields.
Contents
Starters
Install ruby
> sudo apt-get install ruby irb rdoc
Features
Here we list the interesting features that make ruby so interesting, besides its interesting programming features. These are the extra tools that make working with ruby appealing and easy.
- interactive shell (irb),
- extension packages manager (gems),
- documentation generator from in-line comments (rdoc),
- unit-testing framework (utest),
- web-apps development framework (rails),
Python also possesses all of these features built-in (ipython, install, pydoc, unit-tests and django).
Irb
The most interesting thing in shell scripting (bash, dos) is that you can play right from the shell command line. This is what makes interpreted languages so interesting in the first place. Thus, like matlab or python (however, I'm not aware of one for perl), ruby has an interactive shell called irb. Interactive ruby allows to experiment and debug interactively in ruby. Similar (but not so powerful) to ipython.
> irb irb(main):001:0> puts "Hello world!" Hello world! => nil
The most interesting method to call in irb is public_methods which lists all the object's available methods:
irb(main):001:0> puts 11.public_methods.sort.join(" | ")
% | & | * | ** | + | +@ | - | -@ | / | < | << | <= | <=>
| == | === | =~ | > | >= | >> | [] | ^ | __id__ | __send__
| abs | between? | ceil | chr | class | clone | coerce
| denominator | display | div | divmod | downto | dup | eql?
| equal? | extend | floor | freeze | frozen? | gcd | gcdlcm
| gem | hash | id | id2name | inspect | instance_eval | instance_of?
| instance_variable_defined? | instance_variable_get | instance_variable_set
| instance_variables | integer? | is_a? | kind_of? | lcm | method | methods
| modulo | next | nil? | nonzero? | numerator | object_id | power! | prec
| prec_f | prec_i | pretty_inspect | pretty_print | pretty_print_cycle
| pretty_print_inspect | pretty_print_instance_variables | private_methods
| protected_methods | public_methods | quo | rdiv | remainder | require
| require_gem | respond_to? | round | rpower | send | singleton_method_added
| singleton_methods | size | step | succ | taguri | taguri= | taint | tainted?
| times | to_a | to_bn | to_f | to_i | to_int | to_r | to_s | to_sym | to_yaml
| to_yaml_properties | to_yaml_style | truncate | type | untaint | upto | zero? | | | ~
=> nil
Gems
Requires rubygems to be installed. Rubygems is the extension manager for ruby. Much like cpan is the extension manager for Perl. Gems is more than a packaging manager: it's a library versioning manager too! That is also it's achille's heel.
Rdoc
Rdoc is the automatic html documentation generator for ruby scripts. Much like javadoc is for java. It requires rdoc to be installed.
> rdoc --main mywork/mywork.rb
Unit testing
Unit tests are XP's method of choice to build safe long-lasting software. Still looking to see how these work...
Rails
Hopefully we'll get there soon enough...
Ruby2exe
rubyscript2exe allows to transform ruby scripts into full-bloated executable programs.
> gem install rubyscript2exe
Sample code
loop
object = Array.new(["one", "two", "three", "four"])
object.each do |a|
puts a + "\n"
end
array
object = ["one", "two", "three", "four"]
target = []
object.each { |a|
target.push(a)
} puts target
i/o
if File.exist? "sample.txt"
File.open("sample.txt", "r") { |fs|
while line = fs.gets
puts "Line read was '#{line.chomp}'.\n"
end
fs.close
}
end
File.open("sample.txt", "w") { |fw|
fw.puts "Hi, this a new line.\n" fw.close
}
regexp
pattern = Regexp.new("[a-z]+", "i")
- or
pattern = /[a-z]+/i if File.exist? "sample.txt"
File.open("sample.txt", "r") { |fs|
while line = fs.gets
if line.match(pattern)
puts "Line read was '#{line.chomp}'.\n"
end
end
fs.close
}
end
method
def whatisit?(arg1, arg2="optional")
#Ducktyping: Does it walk like a duck? Does quacks like a duck?
if arg1.responds_to? :capitalize
puts "Then '#{arg1.capitalize}' must be a string.\n"
else
if arg1.responds_to? :modulo && arg1.responds_to? :numerator
puts "Then '#{arg1.to_s}' must be an integer.\n"
else
if arg1.responds_to? :modulo && arg1.responds_to? :truncate
puts "Then '#{arg1.to_s}' must be a float.\n"
end
end
end
puts "Input '#{arg2}' was completely optional.\n"
end
class
- File checktype.rb
class Checktype
#Constructor def initialize(arg) #class Checktype field @variable = arg end
#class Checktype method
def isWhat?(arg=@variable)
#Ducktyping: Does it walk like a duck? Does it quack like a duck?
if arg.responds_to? :capitalize
puts "Then '#{arg.capitalize}' must be a string.\n"
else
if arg.responds_to? :modulo && arg.responds_to? :numerator
puts "Then '#{arg.to_s}' must be an integer.\n"
else
if arg.responds_to? :modulo && arg.responds_to? :truncate
puts "Then '#{arg.to_s}' must be a float.\n"
end
end
end
end
end
require 'checktype'
somevar = Checktype(23)
somevar.isWhat?
- => '23' must be an integer
Checktype.isWhat? "Hi"
- => 'Hi' must be a string
