Chapter 15. Ten Features That Set Ruby Apart
In This Chapter
Exploring Ruby's oddities
Using mixins, unit testing, and other stuff
Quacking like a duck
This chapter highlights some of Ruby's unique features. I list the features in no particular order. I cover many of these features in Chapters 5 and 6, but a few of this chapter's features blaze new Ruby territory.
Hashes
A hash
is a collection of key/value pairs. Use curly braces {} to define a hash; use brackets [] to refer to a particular hash value.
price_of = {'Book' => 20.00, 'Shirt' => 15.05, 'Cup' => 10.20} price_of['Car'] = 23999.99 puts price_of['Car']
The output of this brief program is 23999.99
.
For more info, see Chapter 5.
Open Classes
You can add definitions to a class at any point in the code. For example, in the following program, the definition of MyClass
ends before the creation of my_object
. Then the MyClass
definition resumes after the creation of my_object
.
class MyClass def my_method 10 end end my_object = MyClass.new print my_object.my_method, " " class MyClass def another_method 22 end end print my_object.another_method
The output of this program is 10 22
.
For more on open classes, see Chapter 6.
Duck Typing
If it walks like a duck and it quacks like a duck, then it's a duck. Consider the following program. At first, the value
variable walks and quacks like an integer. At that point in the code, value
is an integer. So value.times
is legal but value.each
is illegal. (If you uncomment the first value.each
line and try to ...
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