Changes between Initial Version and Version 1 of SummaryRuby

Timestamp:

Jan 11, 2014, 4:39:53 PM (12 years ago)

Author:

Thanatermesis

Comment:

--

SummaryRuby

@@ +1 @@
+{{{
+#!ruby
+#!/usr/bin/env ruby
+
+$SAFE = 4 # set the security value at the highest prior unless we need more freedom
+require 'a'  # will load a.rb, only one time
+load 'a.rb'  # will load a.rb, every time called this line
+
+#
+# Structure
+#
+
+# Classes:
+class Animal
+    # this sets a public id/varible that can be used for our objects,
+    # independently of being or not declared in the class, we can already use them
+    attr_accessor :lenght, :color  # both read and write
+    attr_reader :lenght, :color    # read-only
+    attr_writer :lenght, :color    # write-only (setter)
+
+    # this method will be called when creating a new object, it requires
+    # arguments if we state them
+    def initialize(given_name="Unknown", given_age)
+
+        # the funny here is that if you call "dog = Animal.new(5)", it will
+        # understand that you are passing the second parameter and set Unknown
+        # to name automatically
+        @name = given_name  # create variables for the objects that we can use,
+                            # from the given arguments
+        @age = given_age
+
+        # variables with @@ instead of @ are accessible only for classes as a
+        # whole, not by the instance of the objects, useful for store
+        # information relevant to all objects of the same class
+        if defined?(@@number_of_squares)
+            # variable already exists for all objects when the first one is created
+            @@number_of_squares += 1
+        else
+            # create the variable first time when the first object is created
+            @@number_of_squares = 1
+        end
+    end
+
+    def self.count
+        @@number_of_squares  # will return the number of objects when Animal.count is called
+    end
+
+    # this is a simple method, used to perform actions to objects (like a function)
+    def name
+        # when calling "dog.name" will return "lassie" for example, "return" is optional
+        return @name
+    end
+
+    # if you want to set the age in another moment than when initialized, you
+    # need to use this setter function
+    def age=(new_age)
+        # new_age is the parameter given to the call, like "dog.age = 10",
+        # adding = in the name of the method means that the method is used for
+        # assign values
+        @age = new_age
+    end
+
+    def some_error_handled_case
+        # raise an error type with a message if a specific case
+        raise ArgumentError, "Age is too young" if @age < 2
+    end
+
+    # using self here is only accessible when calling the class, instead the
+    # object, like: Animal.show_name
+    def self.show_name  # self acts like an alias to Animal, so:  def Animal.show_name ...
+        puts self  # when called, will print "Animal" (class name)
+    end
+
+    # create an alias to whatever thing to another name
+    alias show_name list_name
+
+
+    private
+    # things from here only accessible from the object itself (instances)
+    # calls: method of an object can call its private methods (inside's class code)
+    # cannot call:  dog.method_private
+    # note: using 'send' you can do it, it invokes methods by name: dog.send(:method_private)
+    def privated_area
+        puts "I will only be shown when another method of this class/object calls this private method"
+    end
+
+    protected
+    # same as private, but callable from different objects of the same class
+    # allowing to communicate between them, like for do comparisons between objects
+    def age_difference_with(other_person)
+        (self.age - other_person.age).abs
+    end
+    # example:  fred = Person.new(34) ; chris = Person.new(25) ;  puts chris.age_difference_with(fred)
+
+    def compare(c)
+        if c.age > age
+            "The other object's age is bigger."
+        else
+            "The other object's age is the same or smaller."
+        end
+        # example:  chris = Person.new(25) ; marcos = Person.new(34) ; puts chris.compare_age(marcos)
+    end
+
+    # back to the elements of code which are public
+    public
+    def summary
+        puts "I can be called normally"
+    end
+
+    private :method1, :method2  # we can also define them on this way
+end
+
+# Inheritance:
+# create a superclass called Doctro from the Person's class (inheritance)
+class Doctor < Person
+    # we have already defined the method "name" in the Person's class, so we extend it:
+    def name
+        # when we call .name method from a Doctor's object, will append like: "Dr. Name"
+        # "super" walks in inheritance of the same methods in their parents
+        "Dr. " + super
+    end
+end
+
+somebody = Person.new("John")
+puts somebody.name # John
+who = Doctor.new("James")
+puts who.name # Dr. James
+puts who.instance_variables # @name
+
+
+
+#
+# Polymorfism:
+#   - calling the method "talk" in Dogs or Cats they do different things, but
+#   you can use it in the same way this is very useful when you need to do the
+#   same action for different objects, for a example a loop of talking animals
+#
+class Dog < Animal
+    def talk
+        puts "Woof!"
+    end
+end
+
+class Cat < Animal
+    def talk
+        puts "Meeew"
+    end
+end
+
+
+
+#
+# Nested classes:
+#   - useful for improve structure/grouping/dependency
+#
+class Drawing
+    class Line
+    end
+
+    class Circle
+    end
+
+    # you can call circle subclasses directly from Drawing too on this way:
+    def Drawing.give_me_a_circle
+        Circle.new
+    end
+end
+
+# the way to call a class inside another class is by using ::
+# trying to use directly Circle will fail, so:
+my_circle = Drawing::Circle.new
+
+#
+# Extensions
+#   - already-defined classes (any of them) can be extended or replaced for
+#     example to the Fixnum objects we can use .minutes to translate a number to
+#     minutes
+class Fixnum
+    # we can extend any class with improvings or modifications
+    def minutes
+        self * 60
+    end
+end
+# and so we can use now:
+puts 5.minutes # 300
+
+
+#
+# Modules
+#
+#   They allows to separate things to avoid clashes, similar to classes, but
+#   they doesn't allows you to instantiate objects, their methods can be
+#   directly used without the need to create objects, they are more like
+#   functions that just processes things, let's say toolboxes of features
+
+module Country
+    class Ruler
+        attr_accessor :name
+    end
+
+    def hello
+        puts "I can say hello without the need to create an object"
+    end
+end
+
+module Toolbox
+    class Ruler
+        attr_accessor :lenght
+    end
+
+    # Mix-in: this will print the name of the class which loaded this module
+    # useful for introducing methods in other's classes
+    #
+    # basically is a method defined outside of any class form, so when
+    # integrating a module inside an external class it will simply work on it
+    def class_name
+        self.class.to_s
+    end
+end
+
+# direct call of the module with its contents
+a = Toolbox::Ruler.new
+a.lenght = 50
+b = Country::Ruler.new
+b.name = "Ghengis Khan"
+
+# get the module features and directly use it
+include Country
+governor = Ruler.new
+
+# you can use the method hello from the module Country, without the need to
+# create or use of objects
+hello
+
+#
+# Flow examples
+#
+
+# loops
+loop do
+    i += 1
+    break if i > 100  # break da loop
+end
+
+while (i == 10)
+    puts "i = 10"
+end
+
+until (i > 10)
+    puts "i finally reached 10"
+end
+
+
+# if
+if 2 == 1
+    puts "universe is broken"
+end
+
+unless 2 == 2
+    puts "universe is broken"
+end
+
+# case
+fruit = "orange"
+case fruit
+    when "orange"
+        color = "orange"
+    when "apple"
+        color = "green"
+    else
+        color "unknown"
+end
+
+# ternary operator
+puts  x > 10 ? "higher than 10" : "lower or equal to 10"
+
+
+
+#
+# Structures:
+# it is an easy and fast way to define attributes and hold data, same as to
+# create an entire class with defined initializators (but without require
+# strictly to set all the parameters)
+Person = Struct.new(:name, :gender, :age)
+fred = Person.new("Fred", "male", 50)
+
+
+
+# variable substitution ways:
+foo = "12345678901234567890"
+# puts the first 10 chars in different ways:
+puts foo[1,10]
+puts foo[0..9]
+puts foo.slice(0,10)
+puts foo.match("^..........").to_s
+
+
+# Arrays:
+a = [1, 2, 3, "four"]
+a << 5
+a.push 6
+puts a.empty? # false
+puts a.include?("four") # true
+
+# Hashes (associative arrays)
+dictionary = { 'cat' => 'feline animal',
+               'dog' => 'canine animal',
+               'tags' => ['books',
+                   'libraries',
+                   'knowledge'] }
+puts dictionary['cat'] # shows description
+puts dictionary['tags'].first # shows the first array element for the subarray tags
+dictionary.delete("cat")
+dictionary.delete_if { |key, value| value =~ /feline/ }
+
+
+# Code blocks
+def each_vowel
+    %w{a e i o u}.each { |vowel| yield vowel }
+end
+
+each_vowel { |v| puts v + " is a vowel" }
+# the delimiter of "each" can be modified passing an argument like .each(',') or
+# changing the input delimiter variable $/
+
+
+
+#
+# Errors handling
+#
+class GetWeb
+    begin
+        # block of code where can happen errors
+        a = (10 / 0)  # if this doesn't works...
+    rescue => e
+        a = 10  # let's still use the original value in failed cases, instead of exit/error
+        puts "class of exception is: " + e.class.to_s
+    end
+end
+
+# another example:
+data = ""
+begin
+    #<..code to retrieve the contents of a Web page..>
+    #data = <..content of Web page..>
+rescue ZeroDivisionError
+    #... code to rescue the zero division exception here ...
+rescue YourOwnException
+    #... code to rescue a different type of exception here ...
+rescue
+    puts "The Web page could not be loaded! Using default data instead."
+    #data = <..load data from local file..>
+end
+puts data
+
+
+# If you want to run a script in debug mode, "ruby -r debug script.rb", use
+# step, break, watch, cont, etc...
+
+
+
+# Catch & Throw:
+# note: catch & throw is useless and confusing, avoid it
+# catch & throw works in a similar way as rescue/raise, but using symbols rather than exceptions
+catch(:finish) do
+    1000.times do
+        x = rand(1000)
+        # we will exit the loop "catch" containing the symbol :finish if we got this case
+        throw :finish if x == 123
+    end
+
+    puts "Generated 1000 random numbers withoutgenerating 123!"
+end
+
+# another catch & throw example
+def routine(n)
+    puts n # final result will produce: 3 2 1 0
+    throw :done if n <= 0 # exit inifite nested loop if case happens
+    routine(n-1) # nested itself, infinitely
+end
+
+catch(:done) { routine(3) }
+
+
+#
+# Dynamic Code Execution
+#
+
+# executes the code created dynamically
+eval "puts 2 + 2"
+
+# similar:
+my_number = 15
+my_code = %Q{#{my_number} * 2}
+puts eval(my_code)
+
+# String interpolation makes the eval methods powerful tools for generating
+# different features on the fly. This ability is a power unseen in the majority
+# of programming languages
+# - this method adds an accessor to another class,
+# dynamically using class_eval and interpolating a name given externally
+def add_accessor_to_person(accessor_name)
+    Person.class_eval %Q{
+    attr_accessor :#{accessor_name}
+    }
+end
+
+# It’s possible to take the previous example a lot further and add an
+# add_accessor method to every class by putting your class_eval cleverness in a
+# new method, defined within the Class class (from which all other classes descend):
+class Class
+    def add_accessor(accessor_name)
+        self.class_eval %Q{
+            attr_accessor :#{accessor_name}
+        }
+    end
+end
+
+# You can eval code in instances of objects too:
+class MyClass
+    def initialize
+        @my_variable = 'Hello, world!'
+    end
+end
+
+obj = MyClass.new
+obj.instance_eval { puts @my_variable }  # add extra code to an existing object and execute it
+
+# In the same way you can define methods for existing objects
+obj.instance_eval do def new_method ; puts 'born new method in an alive object' ; end ; end
+# better way to define a method for an existing object, if you dont want to use
+# dynamic code execution of eval
+obj.new_method do def new_method ; puts 'born new method in an alive object' ; end ; end
+
+
+
+# example of an "attr_accessor" equivalent writed in dynamic code, which will work in the same way:
+class Class
+    def add_accessor(accessor_name)
+        self.class_eval %Q{
+        def #{accessor_name}
+            @#{accessor_name}
+        end
+        def #{accessor_name}=(value)
+            @#{accessor_name} = value
+        end
+        }
+    end
+end
+
+# You can use this technique to create a multitude of different “code
+# generators” and methods that can act as a “macro” language to perform things
+# in Ruby that are otherwise lengthy to type out.
+
+
+
+#
+# Forks & Processes
+#
+
+# process-ID is returned in the parent but 'nil' in the child, use this to
+# determine which process a script is in
+if fork.nil?
+    exec "ruby other-file.rb"
+end
+
+# fork a child and wait for it
+child = fork do
+    sleep 3
+    puts "Child says 'hi'!"
+end
+puts "Waiting for the child process..."
+Process.wait child
+puts "All done!"
+
+
+
+
+
+
+
+
+#
+# Unit Testing
+#
+#   - default in stdlib is Minitest, but there's also: rspec, minitest,
+#     test/unit, minispec, bacon, testrocket... rspec is also very used
+
+# create a method for test it later
+class String
+    def titleize
+        # we want to use this method for print results like: "This Is A Test"
+        self.capitalize
+        # and we will end later in improving the code like these next commented
+        # lines, because we haven see that the previous test failed in some cases
+        #self.gsub(/\b\w/) {|letter| letter.upcase }
+        #self.gsub(/\s\w/) {|letter| letter.upcase }
+        #self.gsub(/(\A|\s)\w/) {|letter| letter.upcase }
+    end
+end
+
+puts "this is a test".titleize # this will print "This is a test", but we don't want this result, so for avoid bugs:
+
+# method 1 for testing (manual testing)
+# let's add some "assertion" checkers
+#
+# if our method doesn't give us what we exactly expect, fail
+raise "Fail 1" unless "this is a test".titleize         == "This Is A Test"
+# what happens with numbers? let's add this because this is what we expect in any case
+raise "Fail 2" unless "another test 1234".titleize      == "Another Test 1234"
+# and with other chars like ' ?
+raise "Fail 2" unless "We're testing titleize".titleize == "We're Testing Titleize"
+
+# method 2 for testing
+require 'test/unit'
+# there's also "Minitest" (included in stdlib) and "Bacon" for unit testing
+class TestTitleize < Test::Unit::TestCase
+    def test_basic
+        assert_equal("This Is A Test", "this is a test".titleize)
+        assert_equal("Another Test 1234", "another test 1234".titleize)
+        assert_equal("We're Testing", "we're testing".titleize)
+    end
+end
+
+# method 3 for testing: use Minitest instead, seems like more easier and fast to use option
+module DataStore::AdapterSpec
+    it "returns nil for an invalid key" do
+        @adapter.get(:invalid).must_equal nil
+    end
+
+    it "can set a value" do
+        @adapter.set(:foo, 42)
+        @adapter.get(:foo).must_equal 42
+    end
+end
+# from:  http://wojtekmach.pl/blog/2013/07/17/sharing-examples-in-minitest/
+# more: http://blog.arvidandersson.se/2012/03/28/minimalicous-testing-in-ruby-1-9
+
+
+
+#
+# Misc
+#
+# run when finish
+at_exit { puts "#{Dir.pwd}" } # enqueue a job for when the application has finished to run
+# trap
+trap("SIGINT") do
+    puts "signal INT trapped!, what we should do?"
+end
+
+
+# Using Files
+puts "It exists" if File.exist?("text.txt")
+
+File.open("text.txt") { |f| puts f.gets }  # show file contents (cat)
+
+f = File.new("text.txt", "r")
+puts f.gets
+f.close
+
+data = File.read("text.txt")
+array_of_lines = File.readlines("text.txt")
+
+f = File.open("text.txt")
+puts f.gets
+puts "position in file is: " + f.pos
+f.pos = 8
+puts "position in file has moved to: " + f.pos
+
+# by using File.open in a block, is not needed to close the file when finish
+File.open("text.txt", "w") do |entry| entry.puts "Hi" end
+# note that the next line is invalid, if you put a space before ( then is not an argument list what you pass to it
+#File.open ("text.txt", "w")  do |entry| entry.puts "Hi" end
+
+# appending
+f = File.open "text.txt", "a"
+f.puts Time.now
+f.close
+
+# See the modified time of a file
+f = File.mtime "text.txt"
+puts f.hour # since the object returned (f) is a Time object, we can treat him as it
+
+
+#
+# Docs
+#
+# In documentations, "Array#sample" means the instance method of a class
+
+#= RDoc Example
+#
+#== This is a heading
+#
+#* First item in an outer list
+# * First item in an inner list
+# * Second item in an inner list
+#* Second item in an outer list
+# * Only item in this inner list
+#
+#== This is a second heading
+#
+#Visit www.rubyinside.com
+#
+#== Test of text formatting features
+#
+#Want to see *bold* or _italic_ text? You can even embed
+#+text that looks like code+ by surrounding it with plus
+#symbols. Indented code will be automatically formatted:
+#
+# class MyClass
+#   def method_name
+#     puts "test"
+#   end
+# end
+#
+#--
+# This section is hidden from RDoc and could contain developer
+# notes, private messages between developers, etc.
+#++
+# RDoc begins processing again here after the ++.
+#
+
+# run "rdoc file.rb" to generate the documentation
+# by adding in a class or element "#:nodoc: all" there's no docs generated (for
+# the entire class)
+
+
+
+#
+# Debug
+#
+#   - ruby -d foo.rb:  see page 190 of "begining ruby" which has some basic demo
+
+
+# SAFE levels
+#
+# Value of $SAFE         Description
+# 0     No restrictions. This is the default safe level.
+# 1     Potentially unsafe methods can’t use tainted data. Also, the current
+#       directory is not added to Ruby’s search path for loading libraries.
+# 2     The restrictions of safe level 1, plus Ruby won’t load any external
+#       program files from globally writable locations in the filesystem. This is to
+#       prevent attacks where hackers upload malicious code and manipulate existing
+#       programs to load them. Some potentially dangerous methods are also
+#       deactivated, such as File#chmod, Kernel#fork, and Process::setpriority.
+# 3     The restrictions of level 2, plus newly created objects within the
+#       program are considered tainted automatically. You also cannot untaint objects.
+# 4     The restrictions of level 3, plus nontainted objects created prior to
+#       the safe level being set cannot be modified. You can use this to set up an
+#       execution environ- ment in a lower safe mode, and then provide a way to
+#       continue execution while protecting the original objects and environment.
+
+
+
+
+
+#
+# MORE:
+#
+# regex:
+# Try regular expressions in realtime!  http://rubular.com/
+#
+# references:
+# http://www.zenspider.com/Languages/Ruby/QuickRef.html
+# http://www.tutorialspoint.com/ruby/ruby_quick_guide.htm
+# "Begining Ruby - book": useful classes and methods, errors, regex, variables, etc...  from pag. 575
+#
+# standard lib:
+# http://www.ruby-doc.org/stdlib-2.1.0/
+
+}}}
+