romain-trotard

Recently, during the migration to React 17, I had a problem between event listeners handled by React and one added document manually. It was due to this part on the React 17 release note.

At this moment I understood that I had a misconception of how React handles event listener. So I decided to explore the React code to understand how it works.

The misconception

Before going deep in the React codebase, I would like to explain what was in my head about the management of event listeners.

For example when I write this simple code:

sindresorhus

Pure ESM package

The package that linked you here is now pure ESM. It cannot be require()'d from CommonJS.

This means you have the following choices:

1. Use ESM yourself. (preferred)
   Use import foo from 'foo' instead of const foo = require('foo') to import the package. You also need to put "type": "module" in your package.json and more. Follow the below guide.
2. If the package is used in an async context, you could use await import(…) from CommonJS instead of require(…).
3. Stay on the existing version of the package until you can move to ESM.

edadma

def pow(x: Int, n: Int) = {
  def pow(y: Int, x: Int, n: Int): Int =
    n match {
      case 0 => 1
      case 1 => x * y
      case _ if n % 2 == 0 => pow(y, x * x, n / 2)
      case _ => pow(x * y, x * x, (n - 1) / 2)
    }

  if (n < 0) sys.error(s"pow: negative exponent: $n") else pow(1, x, n)

slikts

Why using the children prop makes React.memo() not work

I've recently ran into a pitfall of [React.memo()][memo] that seems generally overlooked; skimming over the top results in Google just finds it mentioned in passing in a [React issue][regit], but not in the [FAQ] or API [overview][react-api], and not in the articles that set out to explain React.memo() (at least the ones I looked at). The issue is specifically that nesting children defeats memoization, unless the children are just plain text. To give a simplified code example:

const Memoized = React.memo(({ children }) => (<div>{children}</div>));
// Won't ever re-render
<Memoized>bar</Memoized>
// Will re-render every time; the memoization does nothing

vaemendis

<?xml version="1.0" encoding="utf-8"?>
<xs:schema elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="ComicInfo" nillable="true" type="ComicInfo" />
  <xs:complexType name="ComicInfo">
    <xs:sequence>
      <xs:element minOccurs="0" maxOccurs="1" default="" name="Title" type="xs:string" />
      <xs:element minOccurs="0" maxOccurs="1" default="" name="Series" type="xs:string" />
      <xs:element minOccurs="0" maxOccurs="1" default="" name="Number" type="xs:string" />
      <xs:element minOccurs="0" maxOccurs="1" default="-1" name="Count" type="xs:int" />
      <xs:element minOccurs="0" maxOccurs="1" default="-1" name="Volume" type="xs:int" />

alexlee-gk

#Install blender as a module with python 3.5 and pyenv

Tested on Ubuntu 14.04.

Setting up a new python environment using pyenv

Follow instructions from here.

Installing boost

Follow instructions from here.

tatocaster

public class RealPathUtil {

    public static String getRealPath(Context context, Uri fileUri) {
        String realPath;
        // SDK < API11
        if (Build.VERSION.SDK_INT < 11) {
            realPath = RealPathUtil.getRealPathFromURI_BelowAPI11(context, fileUri);
        }
        // SDK >= 11 && SDK < 19
        else if (Build.VERSION.SDK_INT < 19) {

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

pfig

#!/bin/bash

# from
# http://bergamini.org/computers/creating-favicon.ico-icon-files-with-imagemagick-convert.html

convert source-WxW.png -resize 256x256 -transparent white favicon-256.png
convert favicon-256.png -resize 16x16 favicon-16.png
convert favicon-256.png -resize 32x32 favicon-32.png
convert favicon-256.png -resize 64x64 favicon-64.png
convert favicon-256.png -resize 128x128 favicon-128.png

mvasilkov

from functools import partial, wraps

def power_tail(x, a, n):
    assert n >= 0
    if n == 0:
        return x
    elif n & 1:
        return partial(power_tail, x * a, a, n - 1)
    else:
        return partial(power_tail, x, a * a, n >> 1)