Source code for HelloWorld.challenge
"""This is the HelloWorld challenge to teach the usage of the library by a
minimal example.
This challenge takes a number and a word and composes a new word based
on the input.
The class fully focuses on the "business logic" by overwriting just two
methods of parent class <challenge.challenge.Challenge>:
* <build>: This sets up the data model from the given input lines.
* <calc>: This is the core algorithm of the challenge.
This design pattern is called the "Template Method Pattern". While the parent
class handles the common parts of the challenge flow, the child class just
encapsulates what is special.
The two methods above is just the bare minimum to implement. For more complex
challenges you will overwrite or extend other parts of the parent class.
Have a look into the parent class, especially into the <main> function, that
controls the execution of the challenge. Also have a look into the parents
<__init__> method to see what instance attributes are already prepared to serve
the communication of the methods.
By the class attribute <sample> a small example of the possible input is
given. This is recommended for every challenge. It is useful as input of
unit tests or for the smoke tests with the -k option. For more extended
input, in example from the given data files, this class attribute will be
overwritten by injection of an instance attribute of the same name.
The optional class attribute <expect> the expected output for the given
<sample> sets the expected output. This is typically used by unit tests.
Together <sample> and <expect> serve as documantation of the intention of
the challenge.
"""
from challenges import Challenge
[docs]class HelloWorldChallenge(Challenge):
"""This is the HelloWorld Challenge class.
This challenge takes a word as input and a number at which position
to split the word. It returns a new word composed of the switched parts
with a blank in between and the total length of the new string.
"""
sample = '''
5
WorldHello
'''
"""This is a small exsample of the input. It can be overwritten by
injection.
It is used by the --klass option of the challenge runner.
It is also used by unit tests.
prompt> challenge HelloWorld/ --klass
Hello World
"""
expect = '''
Hello World
11
'''
"""This is the expected output for the given sample.
It is used by unit tests, especially by the full integration test.
"""
[docs] def build(self):
"""Parse the input lines and set up the model."""
self.model.split_at = self.line_to_integers(0)[0]
self.model.word = self.line(1)
[docs] def calc(self):
"""Swap head and tail of the model and store to result."""
first = self.model.word[self.model.split_at:]
second = self.model.word[:self.model.split_at]
word = first + ' ' + second
self.result.word = word
self.result.length = len(word)