[Ruby-tut] It's Object-Oriented!

[JHanson90]

I would like to make something clear to the people that read this forum everyday and take Ruby's uber-cool object-orientedness for granted. A little while back, I said that everything in Ruby was object-oriented. But what does that mean? Let me try to explain the best I can without [...] screwing it up.

code:

PHP: <?php echo "This is" . " text."; ?>

In that code fragment, "echo" is a "contruct" of the PHP language, and the '.' brought the two strings together. What does that mean? In Ruby, there really is no ambiguity:

code:

# Ruby puts "This is " + "text."

That is equivalent to the following (though it might return an error because of Ruby coding standards):

code:

self.puts("This is ").+("text.")

Why? Because, unlike in many other languages where functions are just functions and operators are just operators, everything in Ruby is object-oriented; "puts" is a method of the "self" object (self being the actual program), and "+" is a method that adds its argument to the previous expression.
The most strict idea that everything is OO in Ruby exists; it suggests the most structured foundation for a great, powerful, but easy language that I hope will grow in the Western hemisphere.

On with a Simple Ruby Tutorial.

You will need a Ruby interpreter -> http://www.ruby-lang.org/
> Comments...

code:

# this is a Ruby comment, lasts till end of da line

> Local variables and method names must begin with a lowercase letter.
> There are four important arithmetic methods (these are similar, but not identical, to "operators" in other languages): +, -, *, /. Here are explanations of + and *, some useful ones that differ from other languages:
+ -- This will combine any two expressions of the same type. Methods to ensure they're the same type are explained later.

code:

variable = 5 + 5 # that expression returns 10 variable1 = "super" + "dee" + "duper" # that expression returns string "superdeeduper"

* -- This will multiply two expressions, but that don't necessarily have to be of the same type.

code:

variable2 = "A B C " * 2 # that expression will return string "A B C A B C " variable3 = 2 * "A B C " # this will return an error.  Unlike above, where you could say A B C  teice, you cannot say 2 for an "A B C " amount of times.

> No need for semicolons at the end of each statement, so long as there is still a newline character there.
> Use the "to_s", "to_i", and "to_f" methods to convert their object to the string, integer, and float data types, respectively.

code:

variable4 = '5' # string variable5 = 5 # integer variable6 = 5.0 # floating point variable7 = variable4.to_i + variable5 + variabke7.to_i # that expression returns 15, but... variable8 = variable4 + variable5.to_s + variable6.to_s # that expression returns string "555"

> If, elsif, else just like in other languages. Use == method for equality and != method for inequality, etc. Use "and", "or", and "not" 'logical' methods (like logical operators... )

code:

if (variable9 == variable8 or not variable9 == variable7)         # do something elsif (5 == var)         # do something else else         # otherwise do this end

> Use gets for taking input from the user's keyboard, and it would be a good idea to 'chomp' off the newline character at the end of it too.

code:

variable10 = gets.chomp # get just means 'get', and s means 'string', hence gets or 'get string'

> To define your own methods use the def keyword

code:

def a_method a_parameter         puts a_parameter         "this is what gets returned; it is the last line of code in the method" end variable11 = a_method "Ruby is cool" # declare variable 11 is assigned to the return value of the 'a_method' method, with the parameter "Ruby is cool" puts variable11 # output: "this is what gets returned; it is the last line of code in the method" (puts returns nil, the no-value value in Ruby, so puts a_parameter in the method definition didn't do anything)

A Program

code:

#!/usr/bin/ruby # you can use shebeng and make the file executable on linux, to escape the idea of calling the ruby interpreter yourself def say_hi         "hi" end puts "PROGRAM: You suck at Ruby." print "YOU: " your_response = gets.chomp if your_response.downcase == 'so do you' # the 'downcase' method converts its object to all lowercase, but doesn't affect that direct variable.         puts "PROGRAM: Yeah... well, how about I say hi?"         puts say_hi else         puts "PROGRAM: I'm smart cause int 5 + int 5 = 10 but string 5 + string 5 = 55 :)" end

I am very error-prone; if I made any mistakes, wtd, go ahead and point them out

[wtd]

Very nice.

Have some bits.

Now show people how to create their own classes.

[Tony]

great to see more people interested in Ruby so much Keep it up.