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You are never taught how to build quality software

florianbellmann.com

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Re: You are never taught how to build quality software

#171

Post by digging »

datadeft wrote: post #90
KeplerBoy wrote: post #18

> It will be necessary to deliver software without bugs in time. Seems like a pretty bad premise to start an article on quality software. If you believe you can ship bug free code, it's time to switch careers.

Spicy take on engineering. Why do we accept this for software when do not accept the same in other engineering domains?

In addition to the other answers, there is the perennial and depressing one: Software bugs haven't killed enough people in a suitably visible/dramatic way to be regulated that heavily.

Re: You are never taught how to build quality software

#172

Post by Verdex »

akhosravian wrote: post #137
Gare wrote: post #108

Earlier quoted context omitted.

How about a formal proof? :) I jest, but that should be the gold standard for anything life-critical and good to have for mission-critical software. Alas, we're not there yet.

I’m not a CS academic or a mathematician, but don’t Godel’s incompleteness theorems preclude a formal proof of correctness?

No.

Godel means that we can't have an algorithmic box that we put a program into and out comes a true/false statement of halting.

Nothing is stopping you from writing the proof manually for each program that you want to prove properties for.

ALSO, you can write sub-turing complete programs. Those are allowed to have automated halting proofs (see idris et al).

Re: You are never taught how to build quality software

#173

Post by titzer »

hinkley wrote: post #165
titzer wrote: post #117

We do teach these things, they are just not core CS topics, but rather in other areas, relegated to electives like a software engineering course. At CMU we have entire Master's program for software engineering and an entire PhD program (in my department). We teach exactly the kinds of things the blog post is about, and more. Software Engineering is a whole field, a whole discipline. I get that this is a blog post and…

If my friends hadn’t had such vividly bad experiences with the compiler class, I might not have taken the distributed computing class that was one of the other options to fulfill that category. It’s not the most defining class of my undergrad years, but it was pretty damned close. The fact that most people designing systems don’t know this material inspires a mix of anger and existential dread.

If you're specifically referring to CMU's compilers course, feel free to follow up with me offline.

Re: You are never taught how to build quality software

#174

Post by digging »

fidotron wrote: post #144
sanderjd wrote: post #124

Earlier quoted context omitted.

Yes, but that software is not bug-free. The claim was not "it's impossible to make software that does not exhibit bugs too a casually noticeable degree". People who know how the sausage is made will always know of a bunch of bugs that haven't been fixed exactly because they aren't impactful enough to be worth the effort required to fix them.

If it works within specs it is bug free. It doesn’t matter how it is made if it works within specs, which is one of the real unfortunate truths of software. The other is working out the correct specification is far harder than coding is. For example it is trivial to write a bug free program that multiplies an integer between 3 and 45 by two.

> If it works within specs it is bug free.

No, it's functional. If it has bugs, it's not bug-free. By definition.

Re: You are never taught how to build quality software

#175

Post by hinkley »

titzer wrote: post #173
hinkley wrote: post #165

Earlier quoted context omitted.

If my friends hadn’t had such vividly bad experiences with the compiler class, I might not have taken the distributed computing class that was one of the other options to fulfill that category. It’s not the most defining class of my undergrad years, but it was pretty damned close. The fact that most people designing systems don’t know this material inspires a mix of anger and existential dread.

If you're specifically referring to CMU's compilers course, feel free to follow up with me offline.

No sorry, I was speaking in the general case not about CMU. This was ages ago and elsewhere. It was clear the prof got caught flat footed.

It was practically an elective and these days I hope it’s required.

Re: You are never taught how to build quality software

#176

Post by Verdex »

AnimalMuppet wrote: post #163
Gare wrote: post #108

Earlier quoted context omitted.

How about a formal proof? :) I jest, but that should be the gold standard for anything life-critical and good to have for mission-critical software. Alas, we're not there yet.

Formal proof of what ? That it has no bugs? Ha! You can formally prove that it doesn't have certain kinds of bugs. And that's good! But it also is an enormous amount of work. And so, even for life-critical software, the vast majority is not formally proven, because we want more software than we can afford to formally prove.

This is an interesting point that I think a lot of programming can miss.

Proving that the program has no bugs is akin to proving that the program won't make you feel sad. Like ... I'm not sure we have the math.

One of the more important jobs of the software engineer is to look deep into your customer's dreams and determine how those dreams will ultimately make your customer sad unless there's some sort of intervention before you finish the implementation.

Re: You are never taught how to build quality software

#177

Post by bluGill »

Gare wrote: post #108
codegeek wrote: post #87

Earlier quoted context omitted.

Yep. If you have written production grade software at real companies, you know that the moment you make that new commit (even if 1 liner change), you are now ready to accept that it could break something. yes you can do your unit tests, integration test, User Acceptance Tests and what not. But every code change = new possible bug that you may not be able to catch until it occurs to a customer. Whenever I hear a devel…

How about a formal proof? :) I jest, but that should be the gold standard for anything life-critical and good to have for mission-critical software. Alas, we're not there yet.

Even formally proved code can have bugs. If your requirement is wrong is the obvious thing. I don't work with formal proofs (I want to, I just don't know how), but I'm given to understand they have other real world limits that make them sometimes have other bugs.

Re: You are never taught how to build quality software

#178

Post by johnnyanmac »

duped wrote: post #75
bluGill wrote: post #28

Earlier quoted context omitted.

What society needs is a mix of trade school a traditional university. If a university is not providing both they are failing everyone. (except the straw-man rich kid who will inherit a lot of money but not be expected to either also inherit/run a company or pass the money onto their kids - this is something that happens in story books but doesn't seem to be real world where the rich give their kids lots of advantages…

> If a university is not providing both they are failing everyone. Why? > A pure university education without considering is this degree useful in the real world is a disservice to education. I think this line of thinking is a much bigger disservice to higher education. It was very tiresome as an undergraduate to be surrounded by people that thought this way - and detrimental to everyone's education. "I'll never use…

>"I'll never use this knowledge" is the single worst thing you can say as a student, and it needs to be beaten out of undergrads' heads.

Everyone will think differently. I've never truly be research-minded and there's very much a bunch of odd classes that felt like a waste of my money (something to consider as education gets more expensive). But I do agree that there should be a space to foster researchers and especially one to overall round out a student, even if that space is more niche. I just don't think that everyone needs to go far into debt for that experience if they just want job training.

So I too desire a more explicit divide than "research university vs. industry university" and wish there were some better trade schools focused on software (not 6 month boot-camps. Think of a condensed university program without requirements of electives and maybe less supporting classes). But no one seems to be protesting this much.

Re: You are never taught how to build quality software

#179

Post by makapuf »

AnimalMuppet wrote: post #163
Gare wrote: post #108

Earlier quoted context omitted.

How about a formal proof? :) I jest, but that should be the gold standard for anything life-critical and good to have for mission-critical software. Alas, we're not there yet.

Formal proof of what ? That it has no bugs? Ha! You can formally prove that it doesn't have certain kinds of bugs. And that's good! But it also is an enormous amount of work. And so, even for life-critical software, the vast majority is not formally proven, because we want more software than we can afford to formally prove.

Yeah, if you can have a formally proven compiler from slides, poorly written user stories and clarification phone calls to x86_64 binary then alright.

Re: You are never taught how to build quality software

#180

Post by WJW »

Syntonicles wrote: post #76
addicted wrote: post #14

Earlier quoted context omitted.

Yeah and you can see other disciplines like Aviation where there are so many incredible processes to ensure learning and constant improvement.

Will you please elaborate?

Aviation in particular has a very strong culture around (government mandated) checklists and post-crash investigations. This has both pros and cons. The pros is that every airline learns from the mistakes made by every other airline and over time the system becomes really quite safe indeed. The cons are that it is quite expensive and time consuming.

Imagine if every software company was obliged by law to:

- Every single release has to have been signed off by someone who got their "software release engineer" certification at the software equivalent of the FAA.

- This engineer is required by law to not sign off unless every box on a 534 item checklist has been manually verified.

- Any time an unplanned downtime happens at any company, a government team comes in to investigate the root cause and add points nr 535 through 567 to the checklist to make sure it never happens again.

If such a system was mandated for software companies, most of the common bugs would very rapidly become a thing of the past. Development velocity would also fall through the floor though, and most startups would probably die overnight. Only companies that could support the overhead of such a heavyweight process would be viable, and the barrier to entry would massively increase.

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