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|
Feature: Method Overloading
You can use contracts for method overloading! This is commonly called "pattern matching" in functional programming languages.
```ruby
Contract 1 => 1
def fact x
x
end
Contract C::Num => C::Num
def fact x
x * fact(x - 1)
end
```
Background:
Given a file named "method_overloading_with_positional_args_usage.rb" with:
"""ruby
require "contracts"
C = Contracts
class Example
include Contracts::Core
Contract 1 => 1
def fact(x)
x
end
Contract C::Num => C::Num
def fact(x)
x * fact(x - 1)
end
end
"""
Given a file named "method_overloading_with_keyword_args_usage.rb" with:
"""ruby
require "contracts"
C = Contracts
class Example
include Contracts::Core
Contract C::KeywordArgs[age: Integer, size: Symbol] => String
def speak(age:, size:)
"age: #{age} size: #{size}"
end
Contract C::KeywordArgs[sound: String] => String
def speak(sound:)
"sound: #{sound}"
end
end
"""
Scenario: Positional Args Method 1
Given a file named "positional_args_method_1.rb" with:
"""ruby
require "./method_overloading_with_positional_args_usage"
puts Example.new.fact(1)
"""
When I run `ruby positional_args_method_1.rb`
Then the output should contain:
"""
1
"""
Scenario: Positional Args Method 2
Given a file named "positional_args_method_2.rb" with:
"""ruby
require "./method_overloading_with_positional_args_usage"
puts Example.new.fact(4)
"""
When I run `ruby positional_args_method_2.rb`
Then the output should contain:
"""
24
"""
Scenario: Keyword Args Method 1
Given a file named "keyword_args_method_1.rb" with:
"""ruby
require "./method_overloading_with_keyword_args_usage"
puts Example.new.speak(age: 5, size: :large)
"""
When I run `ruby keyword_args_method_1.rb`
Then the output should contain:
"""
age: 5 size: large
"""
Scenario: Keyword Args Method 2
Given a file named "keyword_args_method_2.rb" with:
"""ruby
require "./method_overloading_with_keyword_args_usage"
puts Example.new.speak(sound: "woof")
"""
When I run `ruby keyword_args_method_2.rb`
Then the output should contain:
"""
sound: woof
"""
Scenario: Incorrect Positional Args Method
Given a file named "incorrect_positional_args_method.rb" with:
"""ruby
require "contracts"
C = Contracts
class Example
include Contracts::Core
# Notice that this method's contract is wider than the one below
# This would cause this method to be called every time but never the one below
Contract C::Num => C::Num
def fact(x)
x * fact(x - 1)
end
Contract 1 => 1
def fact(x)
x
end
end
puts Example.new.fact(4)
"""
When I run `ruby incorrect_positional_args_method.rb`
Then the output should contain:
"""
stack level too deep (SystemStackError)
"""
|
