Nerdsniping: A glimpse into a stubborn mind

https://blog.andyet.com/2014/04/07/nerdsniping

by philip_roberts • 12 years ago

145 92 12 years ago

blog.andyet.com

tatalegma• 12 years ago

"I want my code to execute if port is 80 or 443, and http is false"

Couldn't you simply do this?:

if ((a==='80'||b==='443') && http===false) { ... }

cowsandmilk• 12 years ago

I think the goal was

if (a==='80' || (b==='443'&&http===false)) {...}

ssharp• 12 years ago

I think you're right, but it's funny that both the code and the written explanation do not make that clear. Missing parenthesis in one case and missing comma in the other.

I feel like I tend to use parenthesis when they are not required, but I err on the side of caution and I think it makes things more readable.

mox1• 12 years ago

Either way, it's called "Boolean Logic" and as far as I knew every Computer Scientist had to take this class in college...Not sure how you could get a job as a programmer without understanding that...

romanovcode• 12 years ago

I was working with this guy - he always tried to prove that everything is possible wasting time. He ALWAYS over-complicated simple things. He was horrible to work with and everyone hated him.

Not to say you are just like him etc. but this post reminded me of him because it was probably exactly what he would do.

kbenson2• 12 years ago

Wasting other people's time is a negative, but deepening your understanding of a topic by examining edge cases is generally worthwhile, IMHO.

spenuke2• 12 years ago

Is it really fair to call poor code an edge case? If not for the double-equals typo, which most code reviews would fix, this wouldn't work.

I'm more interested that this team has conversations where person A asks a really simple question that should be able to be tested in 11 seconds, person B gives a patently false answer that mistakes && for ||, which is the very thing person A is asking about. Meanwhile person C goes and spends 11 days looking for a loophole and writing a blog about it.

As a person gearing up for my first web dev position, I really wonder if this is what constitutes professional Javascript development and ask myself if I shouldn't be applying to jobs already.

jmngomes• 12 years ago

I think he's referring to some people's inability to balance technical issues and product commitments (deadlines).

Focusing solely on the means and disregarding the ends is a good way to not deliver anything useful. Most times, things need to be good enough, not technically perfect...

Orangeair• 12 years ago

I think the difference really lies in WHEN you do the examining. If you think to yourself, "Hey, that's cool, I'll check it out later," then there's no problem. However, when it gets to the point where you're thinking, "My code must be 110% correct! This is an immediate priority!" then maybe you should be re-evaluating your decision making process.

e28eta• 12 years ago

I think it's worth pointing out the article writer recognizes this is a distraction. In the comic, nerd sniping causes people to forget they're crossing the street and they wind up being hit by a car, which is a pretty serious distraction from the task at hand.

scjody• 12 years ago

Have I learned anything directly useful?

You probably haven't. But a less experienced programmer has learned why you should always use ===.

adamman• 12 years ago

The example at the end of the article shows how you can have the same problem while always using ===.

pdpi• 12 years ago

The example at the end of the article shows how you deserve all sorts of bad things happening to you if you mutate values in a freaking getter.

AUmrysh• 12 years ago

I think it's a great example of why overriding the default prototype functions is a bad idea.

ronaldx2• 12 years ago

The differences between programming syntax and elementary/Boolean algebra are very awkward to understand clearly and deal with correctly. We clearly understand mathematical algebra to work one way, and we naturally assume programming algebra works the same way, which it doesn't at all.

Here, the antagonist says that b can't be 1 and 2 at the same time, which would be self-evident in mathematical algebra, but turns out to be quite irrelevant to Javascript and to programming paradigms generally (since two statements will never be checked simultaneously).

This difference in how syntax is understood actually presents a barrier to programming for modestly trained mathematicians, who would otherwise be expected to excel.

nmrm5• 12 years ago

This difference in how syntax is understood actually presents a barrier to programming for modestly trained mathematicians, who would otherwise be expected to excel.

Although this is true in general that syntax can be a barrier to entry, the article provides a particularly poor example. If anything, the article demonstrates how mathematical training is good preparation for many pitfalls of programming.

Mathematicians are used to working with various equivalence relations, even in the same context. So if a modestly trained mathematician saw == and ===, she would immediately ask "what is the difference between these two ER's?".

And then when she finds out the essential difference is that you can override ==, it would be clear that all bets are off.

I can't imagine any mathematician taking more than a few minutes and a google search -- let alone 11 days -- to figure out this loophole.

Dewie3• 12 years ago

I can't imagine any mathematician taking more than a few minutes and a google search -- let alone 11 days -- to figure out this loophole.

If anything, mathematicians are incredibly used to overloaded equals operators.

ronaldx2• 12 years ago

Mathematicians are used to working with various equivalence relations, even in the same context. So if a modestly trained mathematician saw == and ===, she would immediately ask "what is the difference between these two ER's?".

This perhaps illustrates my point. While you say == and === are equivalence relations (I would argue they are not), there is a wider problem.

= itself is an assignment operator and should never be considered as an equivalence relation. But it is normal to consider = as algebraic equality for anyone who has completed high school math.

It's a great loss to intuitive understanding that we use = for assignment. If anything, considering Javascript's == and === is a net benefit as programmers are more acutely aware of the issue here.

What percentage of time spent learning to program and recovering bugs is caused by overcoming this misintuition? It's surely a lot.

Wikipedia has further discussion: https://en.wikipedia.org/wiki/Assignment_%28computer_program...

Dewie3• 12 years ago

Here, the antagonist says that b can't be 1 and 2 at the same time, which would be self-evident in mathematical algebra, but turns out to be quite irrelevant to Javascript and to programming paradigms generally (since two statements will never be checked simultaneously).

This isn't really a problem if b is enforced to be immutable.

minusSeven• 12 years ago

Umm , you missed a key point here. The first comparison is == while the second one is ===. These 2 are different. The == checks equivalent. Mathematically speaking he should have used === in both places.

These things are more of quirks of javascript than anything else. The post did nothing but made me hate javascript. Try doing the same in Java !

alistairjcbrown• 12 years ago

I guess we’ve messed with the prototype too much, and JavaScript isn’t really convinced it’s still a proper number anymore.

You're comparing a literal number with an object, which are not the same type.

  2 === new Number(2)
  // => false
  2 == new Number(2)
  // => true

Dewie3• 12 years ago

Defining a number to be a procedure (or 'word' in the parlance) is simple in Forth.

: a 2 ;
: 2 3 ;
a 2 =
a 3 =

The two flags on the top of the stack are now equal.

mathattack• 12 years ago

Is this a case of readability versus theoretical perfection?

antinitro• 12 years ago

var i=0;

var b = {};

b.valueOf = function () {

  return ++i:

};

if (b==1 && b==2) {//success}

gkop• 12 years ago

  var i=0;
  var b = {};
  b.valueOf = function () {
    return ++i;
  };
  if (b==1 && b==2) { console.log("success")}

peterkelly• 12 years ago

And now for exercise 2:

Port the solution to Haskell

chrra• 12 years ago

  newtype X = X (IORef Int)
  instance Num X where
    fromInteger = X . unsafePerformIO . newIORef . fromInteger
  instance Eq X where
    (X a) == (X b) = unsafePerformIO $ do
                       x <- readIORef a
                       y <- readIORef b
                       writeIORef a $ x+1
                       return $ x == y

  ghci> a <- fmap X $ newIORef 1
  ghci> a == 1 && a == 2
  True

Edit: formatting.

okasaki• 12 years ago

even more general:

    let a = 1; _ == _ = True in a == 1 && a == 2

wambotron• 12 years ago

I think the answer to "can something be fuzzy equal to one value and strictly equal to another in JS?" has an easy answer that doesn't take much effort to find. This might be cooler in another language, though.

var b = 2;

b == '2'; // true

b === 2; // true

neil_s• 12 years ago

This is what I was gonna say! I don't know much JS, but after @sgdesign 's recent primer, the answer to the first two conditions seems obvious, b=="2" and b===2. Herpderp is just a cop out, since you could have infinite other variables that b equals, if you set the value to the same thing!

philip_roberts3• 12 years ago

Except the question was b==1 && b===2

mikeryan• 12 years ago

I think you missed a bit of his point which was to make that exact expression evaluate as true

(b == 1 && b===2 && b === herpderp)

gyepi• 12 years ago

Nerdsniping reminds me of the Walt Whitman poem:

   There was a child went forth every day;
   And the first object he look’d upon, that object he became;
   And that object became part of him for the day, or a certain part of the day, or for many years, or stretching cycles of years.

It's especially bad if you'd really rather be doing something other than what you're currently doing.

cinitriqs• 12 years ago

so...

(everything == all && all == everything) == stardust/code

mncolinlee3• 12 years ago

And this is why Javascript can be such an awful language. Leaving off a single equals has such a profound effect, often without a new coder even realizing it while reading the code.

Imagine what happens to your code when someone tries to write a function for its side effects similar to the example seen in the blog post. Then releases it in production for it to break in six months with a feature change.

maxbucknell• 12 years ago

At the end of the article, it is demonstrated that this can happen even with strict equality by overriding the getters. Any language with getter/setter support can do this. Operator overloading can be used for even nefarious ends.

The point is that side effects in code are dangerous, and can be used to mislead a reader.

If this happens, it is not the fault of JavaScript. Anyone who writes code like that for purposes other than demonstration or learning is a moron.

mikeash3• 12 years ago

Not all languages with getter/setter support will invoke them automatically like this.

For example, it's not possible in Java or Objective-C to make an expression of the form a == b, where a and b are plain variables, have any side effects.

sisk• 12 years ago

I'm glad that you said, "can be" because language flexibility is a two way street. You can abuse dynamic typing for good and for evil. I, personally, don't think that's a case for declaring it not worthwhile, rather it reenforces investing the time to properly understand the language.

Fortunately, at this stage, we get the best of both worlds with syntax validators and linters. Abuse as appropriate (whatever that means) and be warned about the rest.

briantakita• 12 years ago

And this is why Javascript can be such an awful language. Leaving off a single equals has such a profound effect, often without a new coder even realizing it while reading the code.

You get used to this as you get seasoned with javascript. Every language has it's quirks. The human brain is remarkably adaptable to using tools & dealing with intricacies. I personally utilize & appreciate the difference between == and === to reduce complexity in the code. I assume the reader also understands such differences.

I also find automated testing, logging, a module system like commonjs, and linters to be useful when programming in javascript. Once these are in place, systems written in javascript are remarkably maintainable & scale with complexity.

at-fates-hands• 12 years ago

> I also find automated testing, logging, a module system like commonjs, and linters to be useful when programming in javascript

Except when I use JSLint. Talk about bringing you back to Earth when you think you've done something remarkable with JS.

mncolinlee3• 12 years ago

Nothing you said actually differs from what I said.

I spent seven years as a Perl programmer. Like Perl, a language can be extremely productive in the hands of a veteran and dangerous with a newcomer due to the unnecessary confusion it generates. At least eq and == are syntactically easier to grok than == and ===.

rmrfrmrf• 12 years ago

There are ways to do stupid things in any language. I don't think anyone would ever tell you that redefining an integer as an object and overwriting its prototypes is an acceptable way to solve...any? problem.

cruise02• 12 years ago

Imagine what happens to your code when someone tries to write a function for its side effects...

The language used can hardly be blamed for that.

pmelendez2• 12 years ago

"And this is why Javascript can be such an awful language."

To be fair, this is breaking Javascript and that is something you could do in other languages, for instance here is a similar version for C++:

http://pastebin.com/seySfpku

mncolinlee3• 12 years ago

Pedantry aside... are you really going to defend Javascript's core method of function handling as good design by using the C function pointer as an example?

On some level, defending JS using C is like saying you can also make a souffle by instead cooking the chicken with the egg still inside it. Both JS and its bad paradigms came from C. You don't arrive at good design by showing that other people also got it wrong.

j2kun• 12 years ago

Now do it in Haskell.

userbinator• 12 years ago

#define int INT

This makes it somewhat obvious that you can't change how basic types work in C++. On the other hand, JS's dynamicity makes for some interesting situations, as seen here. I wouldn't consider it "awful" but it's certainly a language with more "deep complexity" than appears at first glance.

marknutter• 12 years ago

And then you realize that javascript runs everywhere and you smile to yourself and continue coding away.

MatthewWilkes• 12 years ago

Yeah, just use python!

  class B(object):
      def __eq__(self, other):
          return True

  b=B()

It's much more expressive

vernie2• 12 years ago

Okay.

ssdfsdf• 12 years ago

This took you 11 days?!

poweribo• 12 years ago

the classic feigned surprise

level• 12 years ago

Call me nitpicky, but it always bugs me when someone references some content, but doesn't link to it. Specifically the XKCD and Stackoverflow links. Link to the comic and question specifically, rather than making me go hunt for that content.

mfonda2• 12 years ago

I think there was a more general question here that was missed: can a == x && a == y ever be true for any arbitrary values of a, x, and y, where x != y.

From a logical point of view, no, this can never be true. I would suspect this can never be true in javascript, and could only be made true in a language where you can override == to always return true.

I think when most developers use the word "never", what they really mean is "never (within the current context)". This makes conversations a lot simpler. Imagine how difficult conversations would be if you always had to qualify never. "This can never be true (assuming a weird valueOf method hasn't been defined and assuming I didn't modify the javascript interpreter to always return true for == and assuming ...)".

tonyarkles• 12 years ago

Here's a JavaScript example, based on what was in the article.

    var b = {c:0};
    b.valueOf = function() { this.c++; return this.c; }
    b == 1 && b == 2
    > true

mfonda2• 12 years ago

That only works for consecutive integers, not any arbitrary values.

lmkg• 12 years ago

I think there are a few cases of non-transitive equalities in JavaScript, specifically around falsey values. Part of it also has to do with whether x is the right-side input or the left-side input, because that changes type coercion rules.

Aha, found one:

  ['0'] == 0
  > true
  [0] == 0
 > true
  [0] == ['0']
 > false

Transitivity of equality can also never be relied upon when dealing with Floating Point numbers. This is correct and unavoidable behavior, but still surprising to many developers.

gsg• 12 years ago

That's not due to transitivity: ['0'] == ['0'] (and for that matter, ['0'] === ['0']) is also false. These operators compare objects for identity, not structural equality.

russellsprouts• 12 years ago

Something like this could work, to some degree:

        a = {}
        a.valueOf = function() {
           var caller = arguments.callee.caller.toString();
           //parse the caller function, and return 
           //different values based on what comparison is being made. 
        }

But I think this is even worse than the getter on the global object.

tarpherder• 12 years ago

Might not be Java but still interesting, it made me think of one of my favorite little quirks in C++:

  #include <cmath>
  
  //Floating point model: Strict:Precise:Fast
  //Will code execute
  float a = nanf("");
  if (a == a)//S:No P:No F:Yes
      (do something);

  if (a != a)//S:Yes P:Yes F:No
      (do something);

  if (a < 0.f || a > 2.f)//S:No P:No F:Yes
      (do something);

  if (isnan(a))//S:Yes P:Yes F:Yes
      (do something);

NaN's (Not A Number) can propagate a long way through your code, possibly reaching places where they cause real problems. When dealing with input, especially networking, one should always check for NaN's. Basically the rule with NaN's is: The comparison always returns false if any NaN is involved. But as you can see; specifying the fast model throws that out of the window. (Code was otherwise unoptimized.)

In the third statement an otherwise fine check is done to make sure the value in a is sane, it doesn't get changed but its certainly not what you'd want it to be.

Whole lots of fun can be had when serving this to game servers. :D

yeahbutbut2• 12 years ago

And so far everyone has missed telling the poor OP how to avoid writing two equality checks...

    if( [80, 443].indexOf(port) !== -1 && http === false )

skrebbel• 12 years ago

Are you certain that that's an improvement?

yeahbutbut2• 12 years ago

For two options, almost certainly not ;-)

For N ports, or for a port list defined from a config file however it could be. It's even nicer in python:

    ports = [80, 443, ...]
    if port in ports and http:
        ...

Or with underscore:

    var ports = [80, 443, ...];
    if(_(ports).contains(port) && http) {
        ...
    }

Good collections make it better than manually checking the return code or checking an explicit set of port values. Also configuration > magic_nums.

cwmma• 12 years ago

If( ~[80, 443].indexOf(port) && http=== false)

vernie2• 12 years ago

Yikes. I understand that companies use these posts as a form of advertising, but seeing your "application security specialist" struggling with such a basic expression gives me pause.

aaronem• 12 years ago

It's not often I see an HN thread which so aptly demonstrates the exact effect under discussion.

gcr• 12 years ago

This kind of abuse is also available in Python!

    In [3]:
    class TheObjectThatIsEqualToAnything(object):
        def __eq__(self, other):
            return True

    In [4]:
    x = TheObjectThatIsEqualToAnything()

    In [6]:
    x == 3 and x == 5
    Out [6]:
    True

Grue3• 12 years ago

It's not necessarily abuse. I once had to code a dummy object that supported all arithmetic operations with normal numbers and had a special comparison logic that it is never equal to itself. Then you could test if something is a number or a dummy object by comparing it to itself.

forrestthewoods• 12 years ago

And here we all are reading this post during work hours. My god, the amount of productivity lost because of that simple question in chat!

drvortex• 12 years ago

0.25 = 0.25

1 - 3 + 2.25 = 4 - 6 + 2.25

1^2 + 2(1)(1.5) + (1.5)^2 = (2)^2 - 2(2)(1.5) + (1.5)^2

Since a^2 - 2ab + b^2 = (a - b)^2

(1-1.5)^2 = (2-1.5)^2

1 = 2

QED.

Nerdsniping: A glimpse into a stubborn mind

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