This issue describes how to implement the class-customization concept exercise for the python track.
Getting started
Please please please read the docs before starting. Posting PRs without reading these docs will be a lot more frustrating for you during the review cycle, and exhaust Exercism's maintainers' time. So, before diving into the implementation, please read up on the following documents:
This concept exercise is meant to teach an understanding/use of class-customization in Python.
Learning objectives
more fully understand the uses (and possible abuses) of classes in Python
understanding of class members
understand some of the options that can be used to adapt a class for purposes beyond simple object creation, including:
using @staticmethod to provide namespaced functionality without object instantiation.
using @classmethod to provide functionality that modifies class attributes shared across class instances
using __repr__() and __str__() to provide human-readable and understandable class descriptions.
using property() and @property to make getters and setters for the methods of a class
using property() and @property to "compose" or "calculate" and return instance attributes.
using property() and @property to "protect" an attribute from mutation.
using functools.cached_property() to calculate a property via a method, and the cache it for future calls to the property.
Pythons version of "non-public" methods and "private variables" (AKA Name mangling)
Out of scope
class-inheritance, multiple-inheritance, __super()__, class mixins
class-composition -- (beyond the composition needed for the decorators in this exercise)
dataclasses
decorators outside of @property, @staticmethod, and @classmethod (the student should already be exposed to the function version of these in a prerequisite)
generators
coroutines
descriptors (these will get their own exercise)
using a class as a decorator
performance considerations
Concepts
classes
class attributes
class members
class methods, @classmethod
static methods, @staticmethod
decorators
getters & setters (through the use of property() and @property)
instance attributes
instance methods
non-public methods, private variables, and name-mangling
Prerequisites
These are the concepts/concept exercises the student needs to complete/understand before solving this concept exercise.
You can refer to one or more of the resources linked above, or analogous resources from a trusted source. We prefer using links within the Python Docs as the primary go-to, but other resources listed above are also good. Please try to avoid paid or subscription-based links if possible.
The same resources listed in this issue can be used as a starting point for the concepts/links.json file, if it doesn't already exist.
If there are particularly good/interesting information sources for this concept that extend or supplement the concept exercise material & the resources already listed -- please add them to the links.json document.
This file provides information about this concept for a student who has completed the corresponding concept exercise. It is intended as a reference for continued learning.
This can also be a summary/paraphrase of the document listed above, and will provide a brief introduction of the concept for a student who has not yet completed the concept exercise. It should contain a good summation of the concept, but not go into lots of detail.
This should also summarize/paraphrase the above document, but with enough information and examples for the student to complete the tasks outlined in this concept exercise.
For more information on concept exercises and formatting for the Python track config.json , please see concept exercise metadata. The track config.json file can be found in the root of the Python repo.
You can use the below for the exercise UUID. You can also generate a new one via exercism configlet, uuidgenerator.net, or any other favorite method. The UUID must be a valid V4 UUID.
.meta/config.json - see this link for the fields and formatting of this file.
.meta/design.md - see this link for the formatting of this file. Please use the Goal, Learning Objectives,Concepts, Prerequisites and , Out of Scope sections from this issue.
Implementation Notes
Code in the .meta/examplar.py file should only use syntax & concepts introduced in this exercise or one of its prerequisite exercises.
Please do not use comprehensions, generator expressions, or other syntax not previously covered. Please also follow PEP8 guidelines.
In General, tests should be written using unittest.TestCase and the test file should be named <EXERCISE-NAME>_test.py.
While we do use PyTest as our test runner and for some implementation tests, please check with a maintainer before using a PyTest test method, fixture, or feature.
Our markdown and JSON files are checked against prettier . We recommend setting prettier up locally and running it prior to submitting your PR to avoid any CI errors.
Help
If you have any questions while implementing the exercise, please post the questions as comments in this issue, or contact one of the maintainers on our Slack channel.
This issue has been automatically marked as abandoned 🏚 because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.
This issue describes how to implement the
class-customization
concept exercise for the python track.Getting started
Please please please read the docs before starting. Posting PRs without reading these docs will be a lot more frustrating for you during the review cycle, and exhaust Exercism's maintainers' time. So, before diving into the implementation, please read up on the following documents:
Goal
This concept exercise is meant to teach an understanding/use of
class-customization
in Python.Learning objectives
more fully understand the uses (and possible abuses) of
classes
in Pythonunderstanding of
class members
understand some of the options that can be used to adapt a
class
for purposes beyond simpleobject
creation, including:@staticmethod
to provide namespaced functionality withoutobject
instantiation.@classmethod
to provide functionality that modifiesclass
attributes shared acrossclass instances
__repr__()
and__str__()
to provide human-readable and understandable class descriptions.using
property()
and@property
to make getters and setters for the methods of aclass
property()
and@property
to "compose" or "calculate" and returninstance attributes
.property()
and@property
to "protect" an attribute from mutation.using
functools.cached_property()
to calculate a property via a method, and the cache it for future calls to the property.Pythons version of "non-public" methods and "private variables" (AKA
Name mangling
)Out of scope
class-inheritance
,multiple-inheritance
,__super()__
, classmixins
class-composition
-- (beyond the composition needed for the decorators in this exercise)dataclasses
decorators
outside of@property
,@staticmethod
, and@classmethod
(the student should already be exposed to the function version of these in a prerequisite)generators
coroutines
descriptors
(these will get their own exercise)class
as a decoratorConcepts
classes
class attributes
class members
class methods
,@classmethod
static methods
,@staticmethod
decorators
getters
&setters
(through the use ofproperty()
and@property
)instance attributes
instance methods
non-public methods
,private variables
, andname-mangling
Prerequisites
These are the concepts/concept exercises the student needs to complete/understand before solving this concept exercise.
basics
booleans
classes
comparisons
decorators
dicts
functions
higher-order-functions
iteration
lists
numbers
sequences
sets
strings
tuples
Resources to refer to
classes (Python tutorial)
private variables (Python tutorial)
Python Data Model - Python Docs
class property() - (Python Docs)
Real Python: Python's Instance, Class, and Static Methods Demystified
Real Python: Object-Oriented Programming in Python 3
Hints
For more information on writing hints see hints
links.json
For more information, see concept links file
concepts/links.json
file, if it doesn't already exist.links.json
document.Concept Description
Please see the following for more details on these files: concepts & concept exercises
Concept
about.md
Concept file/issue: There is currently no issue or files for the concept. They are TBD.
For more information, see Concept
about.md
Concept
introduction.md
For more information, see Concept
introduction.md
Exercise
introduction.md
For more information, see Exercise
introduction.md
Test-runner
No changes required to the Python Test Runner at this time.
Representer
No changes required to the Python Representer at this time.
Analyzer
No changes required to the Python Analyzer at this time.
Exercise Metadata - Track
For more information on concept exercises and formatting for the Python track
config.json
, please see concept exercise metadata. The trackconfig.json
file can be found in the root of the Python repo.You can use the below for the exercise UUID. You can also generate a new one via exercism configlet, uuidgenerator.net, or any other favorite method. The UUID must be a valid V4 UUID.
79af6c54-c826-4971-833f-2039dd6982bc
Exercise Metadata Files Under
.meta/config.json
For more information on exercise
.meta/
files and formatting, see concept exercise metadata files.meta/config.json
- see this link for the fields and formatting of this file..meta/design.md
- see this link for the formatting of this file. Please use the Goal, Learning Objectives,Concepts, Prerequisites and , Out of Scope sections from this issue.Implementation Notes
.meta/examplar.py
file should only use syntax & concepts introduced in this exercise or one of its prerequisite exercises. Please do not use comprehensions, generator expressions, or other syntax not previously covered. Please also follow PEP8 guidelines.unittest.TestCase
and the test file should be named<EXERCISE-NAME>_test.py
.Help
If you have any questions while implementing the exercise, please post the questions as comments in this issue, or contact one of the maintainers on our Slack channel.