Ruby → User Guide #15 - Ruby - access control

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Earlier, we said that ruby has no functions, only methods. However there is more than one kind of method. In this chapter we introduce access controls .

Consider what happens when we define a method in the "top level", not …

Ruby → User Guide #14 - Ruby - Redefinition of methods

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In a subclass, we can change the behavior of the instances by redefining superclass methods.

ruby> class Human
    |   def identify
    |     print "I'm a person.\n"
    |   end
    |   def train_toll(age)
    |     if age < 12
    |       print "Reduced fare.\n"; …

Ruby → User Guide #13 - Ruby - Inheritance

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Our classification of objects in everyday life is naturally hierarchical. We know that all cats are mammals , and all mammals are animals . Smaller classes inherit characteristics from the larger classes to which they belong. If all mammals breathe, …

Ruby → User Guide #12 - Ruby - classes

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The real world is filled by objects, and we can classify them. For example, a very small child is likely to say "bow-wow" when seeing a dog, regardless of the breed; we naturally see the world in terms of these …

Ruby → User Guide #11 - Ruby - methods

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What is a method? In OO programming, we don't think of operating on data directly from outside an object; rather, objects have some understanding of how to operate on themselves (when asked nicely to do so). You might say we …

Ruby → User Guide #10 - Ruby - Object-oriented thinking

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Object oriented is a catchy phrase. To call anything object oriented can make you sound pretty smart. Ruby claims to be an object oriented scripting language; but what exactly does "object oriented" mean?

There have been a variety of answers …

Ruby → User Guide #09 - Ruby - iterators

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Iterators are not an original concept with ruby. They are in common use in object-oriented languages. They are also used in Lisp, though there they are not called iterators. However the concepet of iterator is an unfamiliar one for many …

Ruby → User Guide #08 - Ruby - control structures

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This chapter explores more of ruby's control structures.

case

We use the case statement to test a sequence of conditions. This is superficially similar to switch in C and Java but is considerably more powerful, as we shall see.

ruby> …

Ruby → User Guide #07 - Ruby - Back to the simple examples

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Now let's take apart the code of some of our previous example programs.

The following appeared in the simple examples chapter.

def fact(n)
  if n == 0
    1
  else
    n * fact(n-1)
  end
end
print fact(ARGV[0].to_i), "\n"

Because this is …

Ruby → User Guide #06 - Ruby - arrays

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You can create an array by listing some items within square brackets ([]) and separating them with commas. Ruby's arrays can accomodate diverse object types.

ruby> ary = [1, 2, "3"]
   [1, 2, "3"]

Arrays can be concatenated or repeated …

Ruby → User Guide #05 - Ruby - Regular expressions

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Let's put together a more interesting program. This time we test whether a string fits a description, encoded into a concise pattern .

There are some characters and character combinations that have special meaning in these patterns, including:

[] - …

Ruby → User Guide #04 - Ruby - Strings

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Ruby deals with strings as well as numerical data. A string may be double-quoted ("...") or single-quoted ('...').

ruby> "abc"
   "abc"
ruby> 'abc'
   "abc"

Double- and single-quoting have different effects in some cases. A double-quoted string allows character escapes by …