Comments

• ctietze

  April 2021 edited April 2021

  When I learned about list comprehensions in Python, I explained it to me in familiar terms, e.g. what it'd be like in Ruby or C, for example. This helps find an answer for the question "what was the Python thing for X in Ruby again...?"

  Example: value types, which I likened to Ruby's OpenStruct

  # 201905280926 Value types in Python 3
  #python #value-type
  
  Python value objects require initializer boilerplate, overloading the `__eq__`
  function for by-value equality, and optionally `__repr__` for String representation
  when `print`ed.[#20210407vt][]
  
  ```python
  class RegularCard
      def __init__(self, rank, suit):
          self.rank = rank
          self.suit = suit
  
      def __repr__(self):
          return (f'{self.__class__.__name__}'
                  f'(rank={self.rank!r}, suit={self.suit!r})')
  
      def __eq__(self, other):
          if other.__class__ is not self.__class__:
              return NotImplemented
          return (self.rank, self.suit) == (other.rank, other.suit)
  ```
  
  For simple structures, the Python equivalent of Ruby's `Struct` or `OpenStruct`
  can be used, named tuples:
  
  ```python
  from collections import namedtuple
  
  NamedTupleCard = namedtuple('NamedTupleCard', ['rank', 'suit'])
  queen_of_hearts = NamedTupleCard('Q', 'Hearts')
  queen_of_hearts.rank # => Q
  ```
  
  In Python 3.7, this can be shortened using the `@dataclass` decorator:
  
  ```python
  from dataclasses import dataclass
  
  @dataclass
  class DataClassCard:
      rank: str
      suit: str
  ```
  
  [#20210407vt]: <https://realpython.com/python-data-classes/>
  

  I also often script command-line things as automations, so I usually have at least 1 note per programming language with copy-pastable instructions on how to create a relative file path securely.

  I have 20 notes tagged "python", only, and 5--10 of them are about function decorators that I found very interesting. So getting side-tracked learning something new was a thing, and it was very fun to play around with that.

  My use case was to build a controller application for Raspberry Pi to playback music with just 1 button for my grandmother. (I was slower than her hearing decayed, so I never finished the project, since by now I think the audio output options would be useless.)

  Author at Zettelkasten.de • https://christiantietze.de/