Aaron Hall

On Stack Overflow, they advertise that the best answers rise to the top. This condition does not always hold. New great answers are still ranked (by default) way below answers that have been there for years, and yet have only gathered a few votes. This issue could be addressed by allowing users to sort by recent votes, but this feature may never appear.

My top 100 or so answers are probably worth reading. I've kinda organized my answers with over 8 upvotes here.

Note that I'm linking to the questions, not specifically my answers, so use Ctrl-f and search for my name to find my answers.

Also note that the stated ethos of the site is that the best answers rise to the top.

It can actually take years for new best answers to rise to the top.

We can improve the speed of the sorting algorithm by voting up good answers and voting down poor ones. So while you're reading content on Stack Overflow, remember to vote early and often.

These are some of my answers on how to use Python's builtin data-types.

Dictionaries are mappings of keys to values (implemented as hash tables). So the keys must be hashable.

Lists and tuples are essentially arrays of pointers to objects. Lists are mutable, they can be changed - but tuples are not.

Since lists are mutable, you can't use them in keys for dicts. But you can use tuples.

• Add a key to a Python dictionary
• How to merge two Python dictionaries in a single expression?
• Difference between the list methods append and extend
• Clone or copy a list
• How to get the size of a list
• Remove identical items from a list and sort it
• Prepend to a list
• Explain slice notation - essentially list, string, and tuple __getitem__ method usage.
• Get the last items of a list
• What are named tuples?
• Reverse a string
• Convert a string to lowercase
• Does Python have a string contains method?
• Determine if a list of words exists in a string
• Why is it str.join(list) instead of list.join(str)?
• Is there a constant for Unicode whitespace?
• Difference between using commas, concatenation, and string formatters - printing options (note that there is a really good example of how not to answer on Stack Overflow here. The advice given is perfectly correct, but it's barely a single complete sentence, it's written in a very informal style, and as a result, it has 0 upvotes. The user sits at 1 reputation point as well.)
• Flush the output of print
• Run a shell command from Python
• Getting the current time
• Check whether a file exists
• Check if directory exists and create it if necessary
• Force division to be floating point

The answers I have on these questions cover important idiomatic statements and control flow in Python.

• Modules' __all__
• What does if __name__ == “__main__”: do?
• Ternary conditional operator
• Accessing the index in Python for loops
• Limit iterations of an enumerated loop
• Manually raising (throwing) an exception in Python
• Why is “except: pass” a bad programming practice?
• How do you properly ignore exceptions
• Catch multiple exceptions in one line
• Print the full traceback without halting the program
• Intended use of the optional else clause of the try statement?
• Good practice to use try-except-else(-finally)?

These answers will cover creation and usage of functions.

In Python, everything is an object. Functions are also objects. That makes it easy to make functions first class citizens.

Functions are instantiated by function definitions and lambda statements. I recommend function definitions over lambdas in Python. Lambdas are basically severely limited functions - they don't know their name or have a docstring, and you can only give them a simple statement to return.

Note also that list comps and generator expressions have subsumed map and filter in Python.

• Local versus global variables
• Using global variables in a function other than the one that created them
• Difference between Generators and Iterators
• Create List of Single Item Repeated n Times
• Map two lists into a dictionary
• Arguments, *args and **kwargs for parameters
• Timeout on a function call
• How does the @timeout(timelimit) decorator work?
• Pairwise circular for loop
• What does the yield keyword do?
• How to write the Fibonacci sequence

These Q&As relate to the fact that in Python, everything is an object. That includes integers.

Most all objects have methods that you as a user are intended to use. They all have special methods that start with double beginning and ending underscores. These are sometimes called "dunder" methods because of that.

• “is” operator behaves unexpectedly with integers
• Adding docstrings to namedtuples
• Static methods
• What is the difference between @staticmethod and @classmethod
• Call an instance of an object
• Best way to implement nested dictionaries - demonstrates allowing inheritance (subclassers) to elegantly change behavior.
• Difference between a mixin and inheritance
• Implement a dict with Abstract Base Classes
• How to use super - dependency injection,
• Understanding Python super() with __init__() methods
• When and how to use __slots__ (Note that this is a huge example, in my mind, of where Stack Overflow fails to meet its promise that the best answers rise to the top. The accepted answerer actually says he wants my answer to be accepted.)
• How do I determine the size of an object in Python
• What is a monkey-patch?
• What's the Enum type good for?
• Difference between __str__ and __repr__
• Implement __ne__ in terms of __eq__?
• Difference between Abstract Class and Interface - (there is none!)
• Understanding __get__ and __set__ and Python descriptors

These Q&As combine multiple elements from the above categories. They don't fit very neatly in the prior sections.

These are also a bit advanced.

• Adding a method to an existing object instance (Do not usually do this, but how is instructive.)
• Determine the size of an object
• Proper way to declare custom exceptions
• Test that a function throws an exception
• Optimization break-even point
• Does enumerate produce a generator object?

Edits are an easy way to get over the early participation hurdles. So pull out Strunk and White, and get to fixing spelling and grammar errors, and removing cruft like sign-offs and apologies. Do not change code (except to fix formatting), or change the meaning of answers, (unless it's your answer).

Next, answer questions. It's easier than asking. Almost all the good questions have been asked.

Not all of the good answers have been given.

You can try to earn rep fast by answering new questions that are liable to be closed as dupes and see maybe 100 views over the next decade. Or you can try to write really good canonical answers to canonical questions, like me.

To get upvotes, consider Socrates on persuasion - you need ethos, pathos, and logos.

• Logos: This is logic and evidence. Better communication of logic and evidence will greatly help you succeed on the site, especially when you're starting with nothing. With code, it's usually easy to demonstrate you have something that works, but you still need to back up your recommendations with strong and readily acceptable reasoning.
• Pathos: This is how you say what you say. For a speaker, it's the emotion conveyed by the words. A disconnect can hurt you. If you have a strong tone (and you're right), you'll usually get more upvotes. I have a personal bias against tone. This probably hurts me, when I say "don't do this" instead of saying "I mean really never ever do this."
• Ethos: This the credibility of the speaker/author. The major source of credibility on Stack Overflow is your reputation point count. (Unless perhaps you have widespread recognition as an expert on the topic at hand.) For better or worse, you can get away with less of logos and pathos if you have ethos. I'm sure I have some material that now benefits from my higher reputation count, but in the beginning, everything I posted was greeted with scepticism and required my appeals to logos to carry it.

The last answer here is a really good example of how not to answer on Stack Overflow. The advice given is perfectly correct, but it's barely a single complete sentence, it's written in a very informal style, and as a result, it has 0 upvotes. The user sits at 1 reputation point as well. No ethos, pathos, or logos.

Some people have had a lot of success in asking good questions. Not me. If you manage to create a formula for demonstrable success in asking questions, let me know how.

Top answerers have written long explanations about how to ask good questions. But they don't ask questions. I don't find their advice to be particularly helpful.

The community is frequently capricious, unhelpful, and rude - especially to newcomers, but also even to me when I've asked questions.

However, here's some guidelines to help improve your odds.

• Don't give them an excuse to close your question. Read the help and the rules for the site carefully. If any portion of your question is off-topic (like asking for resources), they will likely vote to close/delete your question. Don't mention wanting a resource. Just don't do it.
• Don't apologize, explain why you don't know something, go on about how new you are, thank them in advance (it's implied anyways), or sign-off your question (your name is on your post). That stuff is considered noise. All that matters is the question itself.
• Don't write a wall of text. Write so that you are understandable at a 3rd grade level (or below if you can). Separate each sentence, one per paragraph. Bold the actual question. Phrase it as a question. Use a question mark. Use a grammar and a spell check on your English. The less you make the answerers think and think critical things about your question, the better.
• Be super nice. Show some research effort. Use code to demonstrate what you're talking about. Make your example as small as possible. Show what you have to work with, and what you expect the output to be. Don't ask them to code for you.

I don't know what else to tell you. If you make a good-faith effort to follow the guidelines I've given in submitting a question, you may still have incompetent people try to shut your question down. Just stay positive, keep looking for the answer yourself, and if you can find it, feel free to answer your own question.

Stack Overflow also tracks your moderating activities, and awards you with badges at certain points. The moderation tools become more available to you as you earn reputation. (See privileges.)

When you earn access to these tools, remember how you were treated, and try to raise the bar in your treatment of others.

The easiest way to improve others' experiences on the site is to fix obvious and fixable problems with their questions. (See the prior section on asking questions.) Again, that gives you +2 rep for accepted edits. If you're conscientious, you will likely have some edits rejected that should have been accepted - just remain conscientious and continue improving content, and you will be rewarded over the long run.

You can also participate (as you earn the privilege) in reviewing posts. Be conscientious if you do.

If the community, a moderator, or the system tells you you're wrong, then you're (99.9% of the time) wrong by definition. Happily accept your wrongness, try to learn from it, and continue helping as you can. If you get temporarily banned from the review queue from time to time, take a break and come back when your ban is up.

Remember, it's all just internet points, which probably won't be worth anything ever. Maybe something when the singularity hits and AI takes over, but I don't see that happening any time soon, so you have plenty of time until then. (I would think that StackOverflow's internet points would be the most valuable, at that point.)

Although I always used their software, I've always been very frustrated with Microsoft's opacity and lack of documentation.

I have been aware of Linux since the early 90s, (with all the computer magazines in the computer software stores, who could miss the penguin and inquire about him).

I was told, "Use Windows if you want to learn how Windows works. If you want to learn how computers work, use Linux."

After much study, ensuring I had the software I needed (office and development software, basically everything but games) I decided to install Linux.

I started by dual booting Linux and Windows, and when I found that I was only rarely using Windows at all, I began to only access Windows from a virtual machine.

Installing Linux is fairly simple.

1. Create a bootable thumbdrive or CD (google for unetbootin).
2. Boot the computer you want to install it on from that.
3. Follow the instructions to install it.

Note that if you're not careful, or even if you are and something goes wrong, you could wipe any other operating systems you may have installed (like Windows). So backup your data.

If you want to dual boot, it's a little more complicated, but Ubuntu's current installer seems to handle it well..

I much prefer to run Windows in a virtual machine (which is really easy).

Read PEP 8 and the Google Python Style Guide.

Here's some thoughts of how to write good Python.

When writing a script, give it a docstring, and put the mainstuff in a main() function. Do the future imports for Python 2 and 3 compatibility, (unicode_literals if it's new code).

e.g. in script.py:

 1: """Explain purpose for script.py here"""
 2: from __future__ import print_function, division, absolute_import, unicode_literals
 3: 
 4: from something import main_stuff # don't import * 
 5: # if following a tutorial, import the module and do dotted lookups.
 6: 
 7: def main():
 8:     main_stuff()
 9: 
10: if __name__ == '__main__':
11:     main()

The main could then be imported into other

You can also get Python from the official site. If you go that route, you'll want to use pip to install packages.

People used to have trouble installing libraries with compiled C extensions with pip, but I understand that this is now improved.

You should be careful to only use it to install to your user area. I understand Ubuntu does this for pip by default, but other operating systems might not be so thoughtful.

You should probably use pip with virtual environments. There are lots of great tutorials on how to do that.

Anaconda installs a new Python in your user area, along with many other commonly used libraries. I like it for teaching and for beginners because it's a one-shot install of most things you want, and a one-shot remove if you don't like it.

It comes with

• lots of packages not already in the standard library, for example: numpy, pandas, requests, and flask.
• a package manager that can install other things: conda - it can even install R too.
• an IDE: SPyDEr (should work out of the box without configuration, too.)
• Jupyter Notebook - a local app that lets you run Python (and other interactive languages) in your browser.

Start at Chapter 3, The Introduction. The first chapter is trivial, and the second chapter is probably gobbledygook to anyone new to programming.

Keep going through the chapters and you'll get exposed to some of the builtin standard library.

Start with the builtins (chapter 2 of the Library Reference). Chapter one is trivial.

Learn the builtin functions. If you're ambitious, memorize their signatures (that is, the arguments that they take.)

Many of the builtin "functions" are actually types that can be used to type check and can be subclassed, in addition to instantiation.

__import__ is mostly kept around for backwards compatibility. Don't bother using it.

This doc includes comprehensive overviews of expressions, and statements for control flow, importing, etc.

I like to point beginners directly at the grammar file.

The PEPs are Python Enhancement Proposals (like Requests For Change, but we don't like breaking changes in Python.)

I highly recommend beginners to Python read PEP 8 early. Others can come later.

The source code is viewable on github. Start by reading the Python in the Lib directory. Then move on to the C code in other directories (Python, Objects, Modules, Include)

You can get a recent version of emacs here.

I have been using Emacs 24.5, but Emacs 25 also works. I've been building 25, and it's what I've used to put the finishing touches on this page with. I want to try to keep my Emacs up-to-date.

I have drafted nearly 75% of this page on my Android tablet, using a bluetooth keyboard. The app that I used to get it is called Termux.

It's not perfect - Android seems to inelegantly kill processes when it uses too much memory.

Spacemacs allows you to quickly install a "layer" of packages with a single entry in the .spacemacs file, a dotfile (a dotfile is a hidden config file in your home directory, Linux/Unix will hide it.)

It's super easy to install (assuming you have git and are in your home directory), if you already have a .emacs.d directory, you should move it first:

git clone https://github.com/syl20bnr/spacemacs ~/.emacs.d

This gets you the latest spacemacs version and drops it right where your .emacs.d directory should be (move your old one first, if you have one).

An example of a layer is python. Adding that to your .spacemacs dotfile causes emacs to ensure that you have over 20 packages installed that are relevant to programming in Python, and that shouldn't conflict with each other.

Troubleshooting Spacemacs: Sometimes things go wrong. I'm not always sure why. The issue has usually been something to do with compiled emacs lisp (elisp) files becoming incompatible with each other. The fix has been pretty easy so far. I've alternately uninstalled and reinstalled emacs, and deleted the elpa directory from my .emacs.d directory, and when I relaunched emacs, then (almost) everything reinstalled properly and works.

I was putting up with the UX issues to learn it better and expand my horizons. I've gone back to regular emacs to learn more about emacs.

Orgmode is a (now builtin) mode in Emacs that uses a hierarchical outline format to organize information in files.

It's a type of markdown, but it's quite sophisticated as well. It can be used for writing material for publication or presentations, via pdf or web format.

In fact, I'm building this page with Orgmode.

To use Orgmode, just open a file in Emacs with .org as the suffix, and start writing.

It's always good to learn good style early on.

I would definitely pay an early visit to the Google HTML/CSS style guide.

If you're a pedant, like me, you'll want to at least scan and know how to read the developer HTML specification.

There are pretty good CSS references. W3 style

The Google Javascript Style Guide is another resource.