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https://github.com/flbulgarelli/ruby-metaprogramming-kata
https://github.com/flbulgarelli/ruby-metaprogramming-kata
Last synced: 17 days ago
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- Host: GitHub
- URL: https://github.com/flbulgarelli/ruby-metaprogramming-kata
- Owner: flbulgarelli
- Created: 2013-03-01T15:13:27.000Z (over 11 years ago)
- Default Branch: master
- Last Pushed: 2013-07-21T19:36:21.000Z (over 11 years ago)
- Last Synced: 2024-10-17T14:28:13.285Z (29 days ago)
- Language: Ruby
- Size: 105 KB
- Stars: 1
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
ruby-metaprogramming-kata
=========================
Kata about metaprogamming in Ruby, consisting of implementing some design patterns and idioms
# Singleton
## Minimum requirements
Allow any class to understand a ```singletonize``` message, which adds to it a instance/get_instance method, which returns always the same instance of the class.
## Example
```ruby
class Foo
singletonize
#... rest of definitions
end
Foo.instance == Foo.instance #should be true
```
## Optional requirements:
* remove, hide or rename the new method.
* implement trivial - nont thread safe - lazy loading
* allow to parameterize the get_instance selector
# Decorator / Interceptor
```ruby
class Foo
decoratorize
before :foo do |x|
puts x
end
after :bar do |x, y|
puts x
puts y
end
around :baz do |x|
print x
r = proceed
puts r
end
end
class Baz
def foo(x)
puts "foo"
end
def bar(x, y)
puts "bar"
end
def baz(x)
puts "baz"
end
end
decoree = Baz.new
decorator = Foo.new(decoree)
decorator.bar("hello", "world") #should print "bar\nhello\nworld\n"
```
# NullObject
## Minimum requirements
Allow to instantiate a object that answers itself whenever a message is send to it
## Optional Requirements
* Allow to inherit from a null object class
# Pattern Matching
## Minimum Requirement
Implement pattern matching for regular expressions, binding regex groups
## Example
```ruby
"foo bar".matches do
on /(.*)_(.*)/ do |foo, bar|
#....
end
on /(.*)-(.*)-(.*)/ do |foo, bar, baz|
#....
end
fallback do
#....
end
end
```
## Optional requirements
Generalize this to any object, not just regexps
# Multimethod
## Example
```ruby
class Foo
multidef :bar, [Baz, FooBar] do |x, y|
1
end
multidef :bar, [FooBaz, Baz] do |x, y|
2
end
end
Foo.new.bar(Baz.new, FooBar.new) #should return 1
Foo.new.bar(FooBaz.new, Baz.new) #should return 2
Foo.new.bar(FooBaz.new, 2) #should fail, since there is no overloaded version of method bar for Number as second argument
```
# DeafMethod
## Minimum requirement
Allow to define methods using a ```deaf``` keyword instead of ```def```. Such methods does not have any body, since their implementation is empty, and take no arguments.
## Example
```ruby
class Foo
deaf :foo
end
```
should be equivalent to:
```ruby
class Foo
def foo
end
end
```
## Optional requirements
Allow deaf methods to take any number of arguments