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@ -2,7 +2,8 @@
<h1 align="center">What the f*ck Python! 😱</h1>
<p align="center">Exploring and understanding Python through surprising snippets.</p>
Translations: [Chinese 中文](https://github.com/robertparley/wtfpython-cn) | [Vietnamese Tiếng Việt](https://github.com/vuduclyunitn/wtfptyhon-vi) | [Spanish Español](https://web.archive.org/web/20220511161045/https://github.com/JoseDeFreitas/wtfpython-es) | [Korean 한국어](https://github.com/buttercrab/wtfpython-ko) | [Russian Русский](https://github.com/satwikkansal/wtfpython/tree/master/translations/ru-russian) | [German Deutsch](https://github.com/BenSt099/wtfpython) | [Add translation](https://github.com/satwikkansal/wtfpython/issues/new?title=Add%20translation%20for%20[LANGUAGE]&body=Expected%20time%20to%20finish:%20[X]%20weeks.%20I%27ll%20start%20working%20on%20it%20from%20[Y].)
Translations: [Chinese 中文](https://github.com/leisurelicht/wtfpython-cn) | [Vietnamese Tiếng Việt](https://github.com/vuduclyunitn/wtfptyhon-vi) | [Spanish Español](https://web.archive.org/web/20220511161045/https://github.com/JoseDeFreitas/wtfpython-es) | [Korean 한국어](https://github.com/buttercrab/wtfpython-ko) | [Russian Русский](https://github.com/frontdevops/wtfpython) | [German Deutsch](https://github.com/BenSt099/wtfpython) | [Add translation](https://github.com/satwikkansal/wtfpython/issues/new?title=Add%20translation%20for%20[LANGUAGE]&body=Expected%20time%20to%20finish:%20[X]%20weeks.%20I%27ll%20start%20working%20on%20it%20from%20[Y].)
Other modes: [Interactive Website](https://wtfpython-interactive.vercel.app) | [Interactive Notebook](https://colab.research.google.com/github/satwikkansal/wtfpython/blob/master/irrelevant/wtf.ipynb) | [CLI](https://pypi.python.org/pypi/wtfpython)
@ -2596,7 +2597,7 @@ It seems as though Python rounded 2.5 to 2.
#### 💡 Explanation:
- This is not a float precision error, in fact, this behavior is intentional. Since Python 3.0, `round()` uses [banker's rounding](https://en.wikipedia.org/wiki/Rounding#Round_half_to_even) where .5 fractions are rounded to the nearest **even** number:
- This is not a float precision error, in fact, this behavior is intentional. Since Python 3.0, `round()` uses [banker's rounding](https://en.wikipedia.org/wiki/Rounding#Rounding_half_to_even) where .5 fractions are rounded to the nearest **even** number:
```py
>>> round(0.5)
@ -3647,7 +3648,7 @@ What makes those dictionaries become bloated? And why are newly created objects
+ CPython is able to reuse the same "keys" object in multiple dictionaries. This was added in [PEP 412](https://www.python.org/dev/peps/pep-0412/) with the motivation to reduce memory usage, specifically in dictionaries of instances - where keys (instance attributes) tend to be common to all instances.
+ This optimization is entirely seamless for instance dictionaries, but it is disabled if certain assumptions are broken.
+ Key-sharing dictionaries do not support deletion; if an instance attribute is deleted, the dictionary is "unshared", and key-sharing is disabled for all future instances of the same class.
+ Additionaly, if the dictionary keys have been resized (because new keys are inserted), they are kept shared *only* if they are used by a exactly single dictionary (this allows adding many attributes in the `__init__` of the very first created instance, without causing an "unshare"). If multiple instances exist when a resize happens, key-sharing is disabled for all future instances of the same class: CPython can't tell if your instances are using the same set of attributes anymore, and decides to bail out on attempting to share their keys.
+ Additionally, if the dictionary keys have been resized (because new keys are inserted), they are kept shared *only* if they are used by a exactly single dictionary (this allows adding many attributes in the `__init__` of the very first created instance, without causing an "unshare"). If multiple instances exist when a resize happens, key-sharing is disabled for all future instances of the same class: CPython can't tell if your instances are using the same set of attributes anymore, and decides to bail out on attempting to share their keys.
+ A small tip, if you aim to lower your program's memory footprint: don't delete instance attributes, and make sure to initialize all attributes in your `__init__`!
@ -3822,7 +3823,6 @@ The idea and design for this collection were initially inspired by Denys Dovhan'
* https://stackoverflow.com/questions/1011431/common-pitfalls-in-python
* https://www.python.org/doc/humor/
* https://github.com/cosmologicon/pywat#the-undocumented-converse-implication-operator
* https://www.codementor.io/satwikkansal/python-practices-for-efficient-code-performance-memory-and-usability-aze6oiq65
* https://github.com/wemake-services/wemake-python-styleguide/search?q=wtfpython&type=Issues
* WFTPython discussion threads on [Hacker News](https://news.ycombinator.com/item?id=21862073) and [Reddit](https://www.reddit.com/r/programming/comments/edsh3q/what_the_fck_python_30_exploring_and/).