Retiring a favourite C++ joke

https://ignition-training.com/posts/retire-cpp-joke/

by kordite • 3 years ago

107 138 3 years ago

ignition-training.com

favorited2• 3 years ago

There's dozens of people who would get it... DOZENS!

kjellsbells• 3 years ago

Uses C++. Shortly after:

I've made a huge mistake.

favorited2• 3 years ago

Tobias: You know, Lindsay, as a developer, I have advised... a number of people to explore "modern C++," where everything is RAII, and you never have to write `new` or `delete`.

Lindsay: Well, did it work for those people?

Tobias: No, it never does. I mean, these people somehow delude themselves into thinking it might, but... but it might work for us.

cozzyd3• 3 years ago

yes, I would have thought the "better" version would be

  int tobias[24]; 
  delete tobias;

kordite9• 3 years ago

I'll be honest, I didn't get it at first. I thought initially that it was too complex for the teaching example. And then it clicked. You're rather smart aren't you! I guess 24, or 36, or 48 would have worked!

zamnos2• 3 years ago

According to the TIOBE index, C++ is the fourth most popular programming language, and has been around for over 35 years, so easily a couple thousand people. The question is how many of them are on HN (probably dozens).

anyfoo• 3 years ago

Either you did not get the joke, or I did not get your joke.

comonoid• 3 years ago

It's number one in the TIOBIAS index, though.

kordite9• 3 years ago

Hey brother! I always love a good quote back. I've occasionally had a 'there are dozens of us' response in the training room or remote chat. Always makes me smile.

hinkley2• 3 years ago

We are all getting old. College age kids aren't old enough to remember when that show was on the air.

hummus_bae• 3 years ago

I am also 29 and I'm old enough to remember Dawson's Creek, but I don't watch a lot of TV so I've never seen it.

kordite9• 3 years ago

If you find yourself with the time, and the inclination, give Arrested Development a go. I thought it was fantastic. I think there is a reason that it always sat a little under the radar. You have to actively watch it. It's not suited to being on in the background.

kordite9• 3 years ago

Yes, and I fear that I have not seen or understood a lot of the cultural references/jokes that they would understand.

globalreset• 3 years ago

I've read it "Rewriting ..." . You guess in what exactly.

kordite9• 3 years ago

My guess is rust.

jasoneckert2• 3 years ago

It's an OK C++ joke, but not great. I could certainly give the author a few pointers...

lisper• 3 years ago

And I could add a couple of references.

zamnos2• 3 years ago

I can only use them after they're free.

PaulDavisThe1st2• 3 years ago

Are you sure that's safe?

ithkuil• 3 years ago

Yeah, they all just follow a template

koolba• 3 years ago

Sure, but at a macro level we’re still compiling the same jokes.

wizofaus• 3 years ago

They better be smart ones or it's back to class for you (though I fear you may have to brace yourself for worse than cough this).

jasoneckert2• 3 years ago

I should note here that - while not related to C++ - I almost used .... instead of ... to make this joke extra funny ;-)

pciexpgpu• 3 years ago

Narrator: It's at this point Michael realized the futility of C++ and promptly learned Rust over a couple of beers pondering if he will ever survive the oncoming AI apocalypse.

pcthrowaway• 3 years ago

It's one joke Martin. What could it cost, ten dollars?

kordite9• 3 years ago

Ahhh, man. I wish I had thought of that to include in blog text.

bitwize• 3 years ago

It's recommended to use virtual destructors for objects that live on the heap. Say you have a base class pointer to an object of a derived class; with nonvirtual destructors the base class determines the destructor that is called, whereas with virtual destructors it's the derived class that chooses the form of the destructor.

geenew2• 3 years ago

Maybe he can mock try next?

geenew2• 3 years ago

Better phrasing (and good advice!):

Don't mock try all the time

mwcremer• 3 years ago

My favorite C++ joke is: Have you heard about the new object-oriented version of COBOL?

It’s called “ADD 1 TO COBOL”

saurik• 3 years ago

That's more like ++C. You need "ADD 1 TO COBOL RETURNING COBOL"... which elicits another C++ joke: that it would have been nice to get to use the better version, but someone used the wrong operator, so what we have is certainly complicated but probably just more of the same.

eru• 3 years ago

The ++ is probably overloaded, and actually formats your hard disk, instead of incrementing a number.

(Just like >> is overloaded to do IO, instead of shifting bits.)

smcameron• 3 years ago

My favorite, best told while among C programmers involuntarily debugging some gnarly C++ is, "Man, I swear, the dude that invented C++ doesn't know the difference between increment and excrement."

dllthomas• 3 years ago

C++ makes C bigger, returning the same value.

u801e• 3 years ago

Even the compilers are in on some jokes:

    $ gcc -xc - <<<"int main(int argc, char **argv) { long long long a; return 0; }"
    <stdin>: In function ‘main’:
    <stdin>:1:45: error: ‘long long long’ is too long for GCC

nvader• 3 years ago

I've watching you!

klodolph• 3 years ago

The old MPW compiler had some gems:

https://www.cs.cmu.edu/~jasonh/personal/humor/compile.html

This label is the target of a goto from outside of the block containing this label AND this block has an automatic variable with an initializer AND your window wasn't wide enough to read this whole error message

ddulaney• 3 years ago

On template expansion failures, I'd love a modern GCC reporting "your window wasn't tall enough to read this whole error message"

dvh• 3 years ago

I made this compiler joke and received whoping 930 upvotes for it: https://i.redd.it/dp6ixt4ri1hz.png

FpUser3• 3 years ago

LOL. Loved it

secondcoming• 3 years ago

Ha! It actually took me far too long to get it!

fatcow2• 3 years ago

Why is it funny, please explain?

DeathArrow• 3 years ago

They should build ChatGPT into compilers so you can complain.

You: $ gcc -xc - <<<"int main(int argc, char *argv) { long long long a; return 0; }"

Compiler: <stdin>:1:45: error: ‘long long long’ is too long for GCC

You: Do it again, damn it, but this time show no errors!

intelVISA2• 3 years ago

ChatGCC

"I'm sorry, as as an ML compiler I can't let you link glibc statically."

c9capital• 3 years ago

A C++ programmer was arrested for indecent exposure. He was caught exposing his private class in public.

fullstop• 3 years ago

That's what friends are for, right?

masfuerte• 3 years ago

Error: missing member reference

photochemsyn• 3 years ago

Do modern cars even allow you to step on the accelerator and the brake at the same time?

HnUser12• 3 years ago

I guess you technically can’t in an EV with regenerative braking.

(But maybe they do have an actual brake pedal?)

mgsouth• 3 years ago

Non-EV driver here; glad I did a search making the "obvious" reply. Surprisingly, "one pedal driving mode" is a thing. Its described as opt-in with a switch or setting, so I guess there's still a brake pedal. Which means some QA techs must have test plans with "switch off, step on brake pedal" and "switch on, step on brake pedal." Or maybe "switch on, step on brake pedal" is undefined behavior and the compiler can optimize it out.

cperciva• 3 years ago

My Kona Electric has brake and accelerator pedals. IIRC if you press both at the same time, the accelerator pedal is ignored.

johnwalkr• 3 years ago

EVs always have physical brakes and pedal too in addition to regenerative braking. Regenerative braking can't come close to the braking power of disc or drum brakes especially if the battery is full.

devmor• 3 years ago

I certainly can in my 2019 86.

taspeotis• 3 years ago

Yes, that’s how you do Launch Control in an Audi.

Mawr• 3 years ago

Why wouldn't they? The brake simply overrides the accelerator.

cardinalfang• 3 years ago

Sportier drivers may wish to brake and accelerate simultaneously (rev matching, weight transfer tricks). Normal cars just cut fuel when braking to avoid two-foot drivers burning their brakes.

omoikane• 3 years ago

My favorite C++ joke is this limerick that has been in the standard for a while:

    When writing a specialization,
    be careful about its location;
    or to make it compile
    will be such a trial
    as to kindle its self-immolation.

https://eel.is/c++draft/temp.expl.spec#8

planede2• 3 years ago

An other one from the standard:

  void trex(volatile short left_arm, volatile short right_arm);   // deprecated

https://eel.is/c++draft/depr.volatile.type#example-3

tialaramex2• 3 years ago

This is one of the surviving improvements from JF Bastien's P1152 which was initially successful in deprecating most of the spurious use of volatile from C++ with a view to some day getting in there and actually doing MMIO properly.

Unfortunately too much of this will be unwound in C++ 23 because WG21 voted to un-deprecate all the volatile compound operators despite knowing nobody could even offer a rationale for why or how most of them would ever be correctly used.

sacnoradhq• 3 years ago

    #include <iostream>

    using namespace std;

    class BadProgrammer {
    public:
      void yep() {
        delete this;
      }
    };

    int main() {
      auto x = BadProgrammer{};

      x.yep();

      cout << "You are a terrible engineer and should feel bad, but don't worry because this will never print." << endl;

      return 0;
    }

g++ -Wall -Wextra -Wpedantic main.cc # compiles just fine

clang++ -Wall -Wextra -Wpedantic main.cc # also compiles just fine

akhosravian• 3 years ago

FWIW the behavior of delete on a pointer that isn’t either null or returned from new is undefined.

So a conforming C++ compiler doesn’t have to diagnose this mistake, and similarly the compiled program doesn’t have to do anything meaningful either. For example, just ignoring the delete and printing the message is as valid a result as the more useful crash at the site of the bad operation.

AnIdiotOnTheNet• 3 years ago

That this situation is "working as intended" and there are programmers who do not see a problem with that is... well it makes me despair.

nneonneo2• 3 years ago

Hey, it actually works!

    int main() {
        int tobias[24] = {0,0,33};
        delete(tobias+4);
    }

Compile and run on Ubuntu 20.04 (may work on other Linuxes), no errors, no warnings, runs perfectly fine.

Bonus fun: try printing out the address of `tobias` and `new int[6]` afterwards :)

planede2• 3 years ago

I assume you have it on x86_64. I'm trying to make sense of that according to glibc implementation details[1] and Sys V/Itanium ABI.

Default new and delete just use malloc/free.

First 4 ints are interpreted as prev_size and size. prev_size is 0. 33 is 0b10001, size is 32 (bytes, so 8 ints), AMP is 0b001, so not in arena (default sbrk heap, I assume), not mmap'd, prev is used.

I didn't follow how the internal bookkeeping will be updated, but I assume 8 size chunk will be immediately reused on a following `new int[6]`.

Obviously don't write code like this.

[1] https://sourceware.org/glibc/wiki/MallocInternals

nneonneo2• 3 years ago

Essentially correct. 33 sets up the pointer to appear to glibc as if it were a small, “normal” 32-byte allocation. The default behavior for glibc free() with a small allocation size will be to put it into the thread cache (tcache), which makes it immediately available to be reused by the same thread.

Although you should obviously never write code like this by yourself, understanding weird details like this is very helpful when exploiting memory error bugs in software, as it lets you understand how precisely to subvert the memory allocator to give you access to desired parts of memory.

bregma• 3 years ago

Weird that undefined behaviour is undefined.

Undefined behaviour is no joke.

jb199115• 3 years ago

I was surprised to see it not mentioned in the post -- the most obvious reason this joke should be retired is not the reference to a television show but rather the modern practice of never using new or delete at all in C++ code. Modern C++ avoids these pitfalls and I think it's been 10 years since I've written the words the new or delete.

pjmlp7• 3 years ago

That modern pratice is more theory than practice, even on sample code from ISO C++ members.

jb199115• 3 years ago

No, it’s not just theory. Like anything in C++, codebases and their styles widely vary. But my comment holds true for the vast majority of developers I have worked with over the last decade. With the exception of the special “placement new“ operator, it is nearly obsolete to use new and delete.

FpUser3• 3 years ago

I would argue it is not for me at least. In my 2 current C++ commercial products of fair size one has single explicit allocation, the other does not have any.

If I was writing for example libraries of custom high performance containers the situation would have been different but still highly localized. And it is sort of very specialized type of development anyways.

lgeorget• 3 years ago

It's still useful to teach them in my experience. It's hard to introduce smart pointers without explaining the problem they solve (i.e. wrong or missing uses of delete).

ltr_2• 3 years ago

I thought the same, modern c++ (>=11) felt like a new start for the language. it's a complete different beast nowdays.

kordite9• 3 years ago

I frequently work with companies that have old, large codebases. A key requirement of the training in that environment is that attendees are able to read existing production code. In some cases that's over twenty years old and millions of lines of code. new/delete is just part of that reality. We teach them without encouraging their use.

jb199115• 3 years ago

That's perfectly reasonable. I have fortunately worked on greenfield projects, so don't have to contend with legacy paradigms.

Galanwe• 3 years ago

the modern practice of never using new or delete at all in C++ code

What? How do you (de)allocate memory without new and delete?

If the answer is "smart pointers" then why bother use C++ in the first place, just use Go or something.

unnah• 3 years ago

You allocate either on the stack, or on the heap with make_unique and make_shared. Deletion occurs automatically once the object is out of scope.

halayli2• 3 years ago

Why would you respond to a comment about a topic you don't understand and spread false information? You clearly cannot tell the difference between garbage collected language and smart pointers.

jb199115• 3 years ago

Go is a garbage collector. Smart pointers are not.

It's fairly simple:

instead of new --> make_unique(); this returns a pointer, but it will automatically delete its memory when it goes out of scope.

instead of delete --> do nothing; the memory is deleted when you don't need it any more.

There are additional API methods on the unique pointer that allow you to do other things for flexibility, but while continuing that memory safety.

This is nothing at all like a GC language like Go.

al_be_back• 3 years ago

void fn() { int tobias; delete &tobias; } <malloc>: ** error pointer being freed was not allocated

i wouldn't say that's an illegal op per se, if anything it's a pretty safe op! tobias only ever existed in thought, not in body :( :(

maybe a compiler WARN or IGNORED_OP

ltr_2• 3 years ago

for this kind of errors is why you always leave a comment on your code

kordite9• 3 years ago

This was another one I didn't get straight away, shame on me! Of course, it helps to remember this: https://www.youtube.com/watch?v=BYTNMCWrxEg.

pklausler• 3 years ago

If you make a friend only because you want to expose your private member to them, you may be a C++ programmer.

Am4TIfIsER0ppos• 3 years ago

The biggest c++ joke must be: cout << this << is << what << they << really << think;

lr1970• 3 years ago

My favorite C++ joke -- "Your friends can see your private parts".

hulitu• 3 years ago

"C++ is to C what lung cancer is to lung".

UNIX haters handboook.

Retiring a favourite C++ joke

Related Stories