python.md

Topics to understand

• Context managers __enter__ and __exit__

• decorators

  • first-class citizens
  • inner/nested functions behaviour
  • higher order functions
  • understand the OOP's design pattern decorator pattern in JAVA
  • closures and closures factories
  • namespaces and scope in python
  • understand flask decorators if you understod this so you understood decorators

  def integer_validator(param_name):
      def decorator(func):
          def wrapper(*args, **kwargs):
              try:
                  param_value = kwargs.get(param_name)
                  if not param_value.isdigit():
                      return jsonify({'error': f'Invalid {param_name}'}), 400
                  return func(*args, **{param_name: int(param_value)})
              except Exception as e:
                  return jsonify({'error': str(e)}), 500
  
          return wrapper
      return decorator

• classmethod

• typing module

• static method

• @property

• @namesetter

• yield

• generators

• map,filter,reduce,enumerate,zip,counter, ...

• lambda functions

• advanced list comperhension

• iterators

• why there is no overloading in python

• dunder methods, know them all

• metaclasses

• descriptors

• dependency intection and inversion of control

• ABC module, @abstractmethod

• logging module

• async python

• mutabilty and immutability in python

• args and **kwargs

• how this syntax is possble

    "DIRS": [BASE_DIR / "templates"],

• late binding vs Duck typing
• functools module
• global and nonlocal
• globals() in python
• object introspection
• timeit module
• advanced usage of f-string and f-string flags
• factory methods

@classmethod
def unit_circle(cls):
    """Factory method creating a circle with radius 1"""
    return cls(1)

• Deeply understand python's OOP

class Circle:
    def __init__(self, radius):
        self.radius = radius

    # mutable property
    @property
    def radius(self):
        """Get value of radius"""
        return self._radius

    @radius.setter
    def radius(self, value):
        """Set radius, raise error if negative"""
        if value >= 0:
            self._radius = value
        else:
            raise ValueError("radius must be non-negative")

    # immutable property
    @property
    def area(self):
        """Calculate area inside circle"""
        return self.pi() * self.radius**2

    # regular method
    def cylinder_volume(self, height):
        """Calculate volume of cylinder with circle as base"""
        return self.area * height

    # class method
    @classmethod
    def unit_circle(cls):
        """Factory method creating a circle with radius 1"""
        return cls(1)

    # static methods
    @staticmethod
    def pi():
        """Value of π, could use math.pi instead though"""
        return 3.1415926535

• dataclasses module in python
• how this syntax is possible

from dataclasses import dataclass

@dataclass
class PlayingCard:
    rank: str
    suit: str

• class decorators, how classes are presented in memory and how they're decorated!!
• any() in python

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To Research

• is there a better way to manage dependencies other thatn requirements.txt. Is Pipfile better that requirements.txt.

• chckout pip-tools

• better way to manage multipe virtual environments and multiple requirements files like requirements-dev.txt requirements-live.txt

• how to acheive public,private,protected in python inheritance

• what happens when you inherete from a class and what is super().__init__()

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Links to visit

• python's standard library documentation here
• The Python Standard Library. The Python Language Reference gives a more formal definition of the language here
• Extending and Embedding the Python Interpreter and Python/C API Reference Manual here
• copying in python Here

Tips

To load .env

from dotenv import find_dotenv, load_dotenv

load_dotenv(find_dotenv(), override=True)

• then to load a varialbe you simply write

import os
variable=os.getnev('VARIABLE_NAME')

Best pracices to structure your project

• Virtual Environments
• Package Management
• Modules and Packages
• Python Packaging
• _init_.py Files
• Class-based Approach
• Configuration Files
• Logging
• Version Control
• Testing
• Documentation
• Linting and Code Formatting
• IDE and Editor Integration

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Best practices to document your code

• Docstrings
• Module-Level Comments
• README.md
• Project Structure and Architecture
• Function and Class Usage Examples
• API Documentation
• Changelog
• Type Annotations
• Use Jupyter Notebooks for Tutorials
• Version Control and Code Hosting Platform

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common errors i encounter

error

• you may encounter this error when you install requirements file
• ERROR: Could not build wheels for backports.zoneinfo, which is required to install pyproject.toml-based projects

solution Edit your requirements.txt file

FROM:

backports.zoneinfo==0.2.1

TO:

backports.zoneinfo;python_version<"3.9"

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Interview questions

• what is the difference between concurrency and multiprocessing in python. how it works in python
• if i have a file on disk and i don't 2 threads to access or write on this file at the same time, how would you handle that. how would you implement this feature yourself withoug using any python features like context managers.
• how hashing works
• can the key of the dictionary in python be any data type other than strings