Ian Fisher iafisher

Notes on object-oriented programming

Overview of object-oriented techniques

Inheritance

Inheritance is a mechanism by which a class is populated with fields and methods not only from its explicit definition, but also from a set of one or more parent classes. Languages with inheritance (among them Java, C++ and Python) typically allow classes to declare that some methods cannot be redefined by child classes (final in Java), some methods must be redefined, and that some fields may not be used by child classes (private versus protected).

Although inheritance was the marquee feature of influential object-oriented languages like Java and C++, its reputation has suffered considerably in recent years. Even Effective Java, one of the most popular guides to the Java language, recommends severely curtailing its use and recommends composition over inheritance and the use of interfaces over

	from iafisher_precommit import Precommit, Problem, checks


	def main():
	precommit = Precommit()

	# Generic checks
	precommit.register(checks.NoStagedAndUnstagedChanges())
	precommit.register(checks.NoWhiteSpaceInFilePath())

	#include <setjmp.h>
	#include <stdio.h>
	#include <stdlib.h>


	const char* e = NULL;


	#define EXCEPTION_DEPTH 128
	jmp_buf* iafisher_trycatch_stack[EXCEPTION_DEPTH];

	#lang racket

	(define-syntax (show stx)
	(syntax-case stx ()
	[(_ x)
	(let ([fully (local-expand #'x 'expression #f)])
	(displayln (syntax->datum fully))
	#'x)]))

	; expect to see (#%plain-lambda (x) x), but get (lambda (x) x) instead

	"""
	A script to automatically export bookmarks from Firefox's SQLite database.

	There does not seem to be a programmatic way to get Firefox to export its bookmarks in
	the conventional HTML format. However, you can access the bookmark information directly
	in Firefox's internal database, which is what this script does.

	Always be careful when working with the internal database! If you delete data, you will
	likely not be able to recover it.

	"""Small but complete example of a Pratt recursive-descent parser for the following
	grammar:

	start := expr

	expr := expr op expr \| call \| LPAREN expr RPAREN \| MINUS expr \| INT \| SYMBOL
	call := SYMBOL LPAREN arglist? RPAREN
	op := PLUS \| ASTERISK \| MINUS \| SLASH

	arglist := (expr COMMA)* expr

	"""
	DEPRECATED: see my bookmarks_from_sql.py gist.

	A short script to parse bookmark exports from Firefox so they can be
	manipulated with Python.

	Author: Ian Fisher (iafisher@protonmail.com)
	Version: November 2018
	"""
	from collections import namedtuple

	import lombok.Data;

	public class Enclosing {
	@Data
	public static class Inner {
	private String value;
	}

	public static void main(String[] args) {
	Inner inner1 = new Inner();

	>>> import mylib, testhelper as th
	>>> fibonacci = th.register(mylib.fibonacci)
	>>> fib(12)
	144
	[testhelper] Is this the expected result (y[es]/n[o]/c[ancel])? y
	>>> fib(-1)
	Traceback (most recent call last):
	...
	ValueError
	[testhelper] Is this the expected result (y[es]/n[o]/c[ancel])? y

	from cryptography.hazmat.backends import default_backend
	from cryptography.hazmat.primitives import hashes
	from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey
	from cryptography.hazmat.primitives.kdf.hkdf import HKDF
	from cryptography.hazmat.primitives.padding import PKCS7

	from cryptography.hazmat.primitives.ciphers import Cipher, modes, algorithms

	import os