? Awesome Falsehood

A curated list of falsehoods programmers believe in.

The logic of the world is prior to all truth and falsehood.
— Ludwig Wittgenstein[1]

Falsehood articles are a form of commentary on a particular subject, and are appreciated by the developer community at large for their effectiveness and terseness. They're a convenient written form to approach an unfamiliar domain by dispelling myths, point out common pitfalls, show inconsistencies and subtleties.

In a sense, Falsehood articles are a suite of wordy unit-tests covering extensive edge-cases provided by real-world usage.

Contents

• Meta


• Arts


• Business


• Dates and Time


• Education


• Emails


• Geography


• Human Identity


• Internationalization


• Management


• Multimedia


• Networks


• Phone Numbers


• Postal Addresses


• Science


• Society


• Software Engineering


• Typography


• Video Games

Meta

• Falsehoods Programmers Believe - A brief list of common falsehoods. A great overview and quick introduction into the world of falsehoods.


• Falsehoods about Programming - A humbling and fun list on programming and programmers themselves.


• Falsehoods about Falsehoods Lists - Meta commentary on how these falsehoods shouldn't be handled.

Arts

• Falsehoods about Music - False assumption that might be made in codifying music.


• Falsehoods about Art - Common misconceptions about art.

Business

• Falsehoods about Online Shopping - Covers prices, currencies and inventory.


• Falsehoods about Prices - Covers currencies, amounts and localization.


• Falsehoods about IBANs - International Bank Account Numbers are not international.


• Falsehoods about Economics - Economics are not simple or rational.


• Falsehoods about Cars - Even something as common as defining a car is full of pitfalls.


• Decimal Point Error in Etsy's Accounting System - The importance of types in accounting software: missing the decimal point ends up with 100x over-charges.


• Characters < and > in company names lead to XSS attacks - Because UK allows companies to be registered with special characters, a hacker leveraged them to register \"><SCRIPT SRC=MJT.XSS.HT></SCRIPT> LTD, but also ; DROP TABLE "COMPANIES";-- LTD, BETTS & TWINE LTD and SAFDASD & SFSAF \' SFDAASF\" LTD.


• CLDR currency definitions - Currency validity date ranges overlap due to revolts, invasions, new constitutions, and slow planned adoption.


• tax - A PHP 5.4+ tax management library.

Dates and Time

• Falsehoods about Time - Seminal article on dates and time.


• More Falsehoods about Time - Part. 2 of the article above.


• Falsehoods about Time and Time Zones - Another takes on time-related falsehoods, with an emphasis on time zones.


• Critique of Falsehoods about Time - Takes on the first article above and provides an explanation of each falsehood, with more context and external resources.


• Falsehoods about Unix Time - Mind the leap second!


• Falsehoods about Time Zones - Has some nice points regarding the edge-cases of DST transitions.


• Your Calendrical Fallacy Is Thinking… - List covering intercalation and cultural influence, made by a community of iOS and macOS developers.


• Time Zone Database - Code and data that represent the history of local time for many representative locations around the globe.


• The Long, Painful History of Time - Most of the idiosyncrasies in time keeping can find an explanation in history.


• You Advocate a Calendar Reform - Your idea will not work. This article tells you why.


• So You Want to Abolish Time Zones - Abolishing timezones may sound like a good idea, but there are quite a few complications that make it not quite so.


• The Problem with Time & Timezones - A video about why you should never, ever deal with timezones if you can help it.


• $26,000 Overcollection by Labor Department - The consequence of wrong calendar accounting.


• ISO-8601, YYYY, yyyy, and why your year may be wrong - String formatting of date is hard.


• UTC is Enough for everyone, right? - There are edge cases about dates and time (specifically UTC) that you probably haven't thought of.


• Storing UTC is not a silver bullet - "Just store dates in UTC" is not always the right approach.


• How to chooose between UT1, TAI and UTC - Depends on your priorities between SI seconds, earth rotation sync, leap seconds avoidance.


• Why is subtracting these two times (in 1927) giving a strange result? - Infamous Stack Overflow answer about both complicated historical timezones, and how historical dates can be re-interpreted by newer versions of software.


• Critical and Significant Dates - From Y2K to the overflow of 32-bit seconds from unix epoch, a list of special date to watch for depending on the system.

Education

• Falsehoods CS Students (Still) Believe Upon Graduating - A list of things (not only) computer science students tend to erroneously and at times surprisingly believe even though they (probably) should know better.


• Postdoc myths - Lots of things are said, written and believed about postdoctoral researchers that are simply not true..

Emails

• I Knew How to Validate an Email Address Until I Read the RFC - Provides intricate examples that are unsuspected valid email addresses according the RFC-822.


• So you think you can validate email addresses (FOSDEM 2018) - Presentation of edge-case email addresses and why you should not use regex to parse them.


• Your E-Mail Validation Logic is Wrong - A summary of the various, surprising things that are allowed in an email address.

Geography

• Falsehoods about Geography - Takes on places, their names and locations.


• Falsehoods about Maps - Covers coordinates, projection and GIS.


• I Hate Coordinate Systems - A guide for geospatial practitioners on diagnosing and fixing common issues with coordinate systems.


• Top 5 most insane kanji place names in Japan - “There's one special group of kanji that's hard even for Japanese people to read: place names.”

Human Identity

• Falsehoods about Names - The article that started it all.


• Falsehoods about Names – With Examples - A revisited version of the article above, this time with detailed explanations.


• Falsehoods about Biometrics - Fingerprints are not unique.


• Falsehoods about Families - You can't really define a family with strict rules.


• Falsehoods about Gender: #1 & #2 - Gender is part of human identity and has its own subtleties.


• Falsehoods about Me - Issues at the intersection of names and gender and internationalization.


• Gay Marriage: The Database Engineering Perspective - How to store a marriage in a database while addressing most of the falsehoods about gender, naming and relationships.


• Personal Names Around the World - How do people's names differ around the world, and what are the implications for the Web?


• XKCD #327: Exploits of a Mom - Funny take on how implementation of a falsehood might lead to security holes.


• Hello, I'm Mr. Null. My Name Makes Me Invisible to Computers - Real-life example on how implemented falsehood has negative impact on someone's life.


• My name causes an issue with any booking! - Old airline reservation systems considers the MR suffix as Mister and drops it.


• HL7 v3 RIM - A flexible data model for representing human names.


• Apple iOS NSPersonNameComponentsFormatter - Localized representations of the components of a person's name.

Internationalization

On character encoding, string formatting, unicode and internationalization.

• Falsehoods about Language - Translating a software from English is not as straightforward as it seems to be.


• Internationalis(z)ing Code - A video about things you need to keep in mind when internationalizing your code.


• Minimum to Know About Unicode and Character Sets - A good introduction to unicode, its historical context and origins, followed by an overview of its inner working.


• Awesome Unicode - A curated list of delightful Unicode tidbits, packages and resources.


• Dark corners of Unicode - Unicode is extensive, here be dragons.


• Let's Stop Ascribing Meaning to Code Points - Dives deeper in Unicode and dispels myths about code points.


• Breaking Our Latin-1 Assumptions - Most programmers spend so much time with Latin-1 they forgets about other's scripts quirks.


• Ode to a shipping label - Character encoding is hard, more so when each broken layer of data input adds its own spice.


• i18n Testing Data - Compilation of real-word international and diverse name data for unit testing and QA.


• Big List of Naughty Strings - A huge corpus of strings which have a high probability of causing issues when used as user-input data. A must have set of practical edge-cases to test your software against.

Management

• Falsehoods about Job Applicants - Assumptions about job applicants and their job histories aren't necessarily true.

Multimedia

• Falsehoods about Video - Cover it all: video decoding and playback, files, image scaling, color spaces and conversion, displays and subtitles.

Networks

• Falsehoods about Networks - Covers TCP, DHCP, DNS, VLANs and IPv4/v6.


• Fallacies of Distributed Computing - Assumptions that programmers new to distributed applications invariably make.


• There's more than one way to write an IP address - Some parts of the address are optional, mind the decimal and octal notations, and don't forget IPv6 either.


• URLs: It's complicated… - There's a lot of components in an URL, and all have their own logic.


• hostname-validate - An attempt to validate hostnames in Python.

Phone Numbers

• Falsehoods about Phone Numbers - Covers phone numbers, their representation and meaning.


• libphonenumber - Google's common Java, C++ and JavaScript library for parsing, formatting, and validating international phone numbers. Also available for C#, Objective-C, Python, Ruby and PHP.

Postal Addresses

• Falsehoods about Addresses - Covers streets, postal codes, buildings, cities and countries.


• Falsehoods about Residence - It's not only about the address itself, but the relationship between a person and its residence.


• Letter Delivered Despite No Name, No Address - Ultimate falsehood about postal addresses: you do not need one.


• The Bear with Its Own ZIP Code - Smokey Bear has his own ZIP Code (20252) because he gets so much mail.


• Regex and Postal Addresses - Why regular expressions and street addresses do not mix.


• Parsing the Infamous Japanese Postal CSV - “I saw many horrors, but I've never seen this particular formatting choice anywhere else.”


• libaddressinput - Google's common C++ and Java library for parsing, formatting, and validating international postal addresses.


• addressing - A PHP 5.4+ addressing library, powered by Google's dataset.


• postal-address - Python module to parse, normalize and render postal addresses.


• address - Go library to validate and format addresses using Google's dataset.

Science

• Falsehoods about Systems of Measurement - On working with systems of measurement and converting between them.

Society

• Falsehoods about Political Appointments - Designing election systems has its own tricks.


• Falsehoods about Women In Tech - Myth about women in STEM (Science, Technology, Engineering, Math) industries.

Software Engineering

• Falsehoods about Versions - Attributing an identity to a software release might be harder than thought.


• Falsehoods about Build Systems - Building software is hard. Building software that builds software is harder.


• Falsehoods about REST APIs - Pitfalls to be mindful of when creating and documenting APIs.


• Falsehoods about CSVs - While RFC4180 to exists, it is far from definitive and goes largely ignored.


• Falsehoods about Package Managers - Covers package and their managers.


• Falsehoods about Testing - An attempt to establish a list of falsehoods about testing.


• Falsehoods about Search - Why search (including analysis, tokenization, highlighting) is deceptively complex.


• Falsehoods about Bitcoin - A list of mistaken perspectives on Bitcoin.


• Falsehoods about Pagination - Why your pagination algorithm is giving someone (possibly you) a headache.


• Falsehoods about garbage collection - Misconceptions about the predictability and performance of garbage collection.


• Myths about File Paths - Diversity of file-systems and OSes makes file paths a little harder than we might think of.


• Myths about CPU Caches - Misconceptions about caches often lead to false assertions, especially when it comes to concurrency and race conditions.


• Myths about /dev/urandom - There are a few things about /dev/urandom and /dev/random that are repeated again and again. Still they are false.


• Hi! My name is… - This talk could have been named "falsehoods about usernames (and other identifiers)".


• Popular misconceptions about mtime - Part of a post on why file's mtime comparison could be considered harmful.


• Rules for Autocomplete - Not falsehoods per-se, but still a great list of good practices to implement autocompletion.


• Floating Point Math - "Your language isn't broken, it's doing floating point math. (…) This is why, more often than not, 0.1 + 0.2 != 0.3."


• The Hidden Complexity of Downloading Favicons, Told in 15+ Edge Cases - Downloading that little icon you see in you browser tabs should be a simple exercise. It turned out to be a lot more complicated than you think. Be vigilant that you are not shaving a Yak.


• Norway is not False - Norway's ISO country code is also valid YAML for False.

Typography

• Falsehoods about Fonts - Assumptions about typography on the web and in desktop applications.


• Truths programmers should know about case - A complete reverse of the falsehoods format, on the topic of case (as in uppercase and lowercase text).

Video Games

• The Door Problem - All the things you have not considered implementing for your doors in games.

Contributing

Your contributions are always welcome! Please take a look at the contribution guidelines first.

Footnotes

The header image is based on a modified photo taken in February 2010 by Iza Bella, distributed under a Creative Commons BY-SA 2.0 UK license.

[1]: Notebooks, 1914-1916, page 14e (Harper & Brothers, New York, 1961). [↑]