Introduction
An important method for code organization is the use of namespaces.
Classes and modules provide namespaces.
Two methods might have a naming collision, which can be resolved by putting them in different namespaces.
Namespaces can be nested, which might help to structure big code bases.
Access to the namespaces is done via the scope-resolution operator ::.
The example below shows the use of two different foo methods.
They are used together by prefixing their respective namespaces.
class MyNamespace
def self.foo
44
end
class MyInnerNamespace
def self.baz
90
end
end
end
class MyOtherNamespace
def self.foo
-2
end
end
p MyNamespace::foo + MyOtherNamespace::foo * MyNamespace::MyInnerNamespace::baz # => -136
Note that namespaces are interpreted based on where the executing code is.
To refer to something in the root namespace, (ie outside all defined namespaces), start with ::.
For example:
class Example
def self.example
5
end
end
class MyNamespace
class Example
def self.example
10
end
end
def self.call_example
p Example::example # => 10
p ::Example::example # => 5
end
end
Instructions
You work for a prestigious law firm that is specialized in handling unique testament requests.
In this exercise, you are going to open a mysterious vault.
You are the executor of the estate and will assemble the long-kept secret codes of three families to get an account number and the matching code.
To prevent any family from opening the vault alone, it can only be opened by combining their knowledge with a secret modifier that you know from the last will.
You have three tasks, all related to helping the families to open the vault.
Define a namespace called EstateExecutor.
The code from the next tasks should be defined in the body of the EstateExecutor namespace.
class SomeName
# The space between the class/module name
# and the `end` keyword
# is called body of the namespace.
end
This is your big moment.
Only you have the secret modifier key to reveal the secret account number.
Define the assemble_account_number(secret_modifier) method that takes the Integer secret modifier as an argument and returns the Integer assembled account number.
To get the correct number, you have to sum up the bank_number_part from each of the three families.
The instructions in the testament ask you to add all the blue and then all the red fragments.
The resulting code is obtained by multiplying both sums.
Define the assemble_code method that returns the resulting code by combining the fragments from the three families to a single Integer result.
The method does not have any arguments and relies solely on the information in the relevant namespaces from the families.
Created by
- @vaeng (original C++ exercise)
- @vaiapatta1985 (transcription to Ruby)
Learning Exercise
