vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

xem

Conventions

• A = [xA, yA] is a point on the 2D plane. Same for B, C, ...
• lengths are in any unit (ex: pixels)
• code snippets are in JavaScript

Degrees to radians

angleRad = angleDeg * Math.PI / 180;

ChrisPenner

from tail_recursion import tail_recursive, recurse

# Normal recursion depth maxes out at 980, this one works indefinitely
@tail_recursive
def factorial(n, accumulator=1):
    if n == 0:
        return accumulator
    recurse(n-1, accumulator=accumulator*n)

ankurk91

Github : Signing commits using GPG (Ubuntu/Mac) 🔐

• Do you have an Github account ? If not create one.
• Install required tools
• Latest Git Client
• gpg tools

# Ubuntu
sudo apt-get install gpa seahorse
# MacOS with https://brew.sh/

kdevo

IntelliJ IDEA and Maven - "Unresolved Plugin" Solutions

⚠️ Probably outdated (from 2016).

Related:

• https://intellij-support.jetbrains.com/hc/en-us/community/posts/206434489
• https://youtrack.jetbrains.com/issue/IDEA-127515

Symptoms

gaearon

If you haven’t worked with JavaScript in the last few years, these three points should give you enough knowledge to feel comfortable reading the React documentation:

• We define variables with let and const statements. For the purposes of the React documentation, you can consider them equivalent to var.
• We use the class keyword to define JavaScript classes. There are two things worth remembering about them. Firstly, unlike with objects, you don't need to put commas between class method definitions. Secondly, unlike many other languages with classes, in JavaScript the value of this in a method [depends on how it is called](https://developer.mozilla.org/en-US/docs/Web/Jav

bvaughn

This API was removed in React 17

---

Interaction tracing with React

React recently introduced an experimental profiler API. After discussing this API with several teams at Facebook, one common piece of feedback was that the performance information would be more useful if it could be associated with the events that caused the application to render (e.g. button click, XHR response). Tracing these events (or "interactions") would enable more powerful tooling to be built around the timing information, capable of answering questions like "What caused this really slow commit?" or "How long does it typically take for this interaction to update the DOM?".

With version 16.4.3, React added experimental support for this tracing by way of a new NPM package, scheduler. However the public API for this package is not yet finalized and will likely change with upcoming minor releases, so it should be used with caution.

devloco

let fnGetFileNameFromContentDispostionHeader = function (header) {
    let contentDispostion = header.split(';');
    const fileNameToken = `filename*=UTF-8''`;

    let fileName = 'downloaded.pdf';
    for (let thisValue of contentDispostion) {
        if (thisValue.trim().indexOf(fileNameToken) === 0) {
            fileName = decodeURIComponent(thisValue.trim().replace(fileNameToken, ''));
            break;
        }

pavlin-policar

class MaxHeap:
    def __init__(self, collection=None):
        self._heap = []

        if collection is not None:
            for el in collection:
                self.push(el)

    def push(self, value):
        self._heap.append(value)

Einstrasse

// C++ includes used for precompiling -*- C++ -*-

// Copyright (C) 2003-2015 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.