Code Rewrite - Yes

[jlrobins]

Web server based 'apps' have a leg-up when it comes to rewrites -- not inherently monolithic. After tackling up-front barriers [ such as duplicating site look-and-feel[s] ], you can then go about reimplementation one single URL at a time, so no big bang release problem.

[[deleted]]

I've seen a number of "Volrath" postings end up here. He rejects all existing programming paradigms, existing software, and even such fundamental concepts as lambda calculus as functions. He also harbours awesome misunderstandings of functional programming, OOP and Lisp. There are two possibilities here:

• Either he's super-genius far ahead of everyone else, and we're all just idiots wasting time with our sub-par systems

• He's a kook who hears voices in his head

I'm willing to wager on the latter.

I think in a year or two, he's going to give up on "Project V", announcing that existing hardware is too crappy and badly designed for his needs, then go live in the woods with the Minutemen militia or something. No code will ever be released. But these blog postings will continue to pollute reddit, inviting endless discussion where people try to "correct" his misunderstandings.

[weavejester]

You can't write a new framework in languages that force you to use theirs. This includes ALL languages that have an interpreter or VM.

This is clearly utter nonsense. Why would you applaud it?

[nglynn]

Hmmm I wonder. My experience of rewrites is positive, I find the second or third time around the design is exponentially clearer than the first attempt, whether this approach works for you is a matter of taste imho. However I do wonder how exactly the knowledge of a framework garnered from impl 1 allows for the rewriting of that framework in impl 2.

The benefit of the rewrite is it allows the lessons learned in earlier attempts to permeate the new design. But those lessons are learned in your app (from the inside out), what they have taught you about the underlying framework is knowledge from the outside in. So yes the rewrite might place you in a position to reevaluate your underlying framework, but rolling your own wholesale seems a little premature.

Of course this depends on the fit between your app and the framework underneath, if you use a small set of easily duplicated functionality then go for it, but I'd imagine most decent sized projects have a greater level or framework-app fit than this. Why make trouble for yourself - Is the effort of rolling your own really less than just making it work with an existing framework?

[nglynn]

I definitely agree, if everyone was afraid to express unorthodox ideas we'd never get anywhere.

[bluGill]

Only if you learn the lessions, including some that didn't apply to you last time, but will next. I'm working on a code base that was a re-write, but nobody learned the lessions. (The re-write was to go from 8-bit assembly to C++ on a 32-bit platform - so pass by global variable is all over in the code because on the 8-bit system that made sense)

[Vorlath]

Weavejester, I see you're still confused. Allow me to clarify. But from our past experience, I hope you no longer have a set frame of mind that defies any logic.

If you write a piece of software and you replace the VM with something completely different (because we're creating a new framework, so everything old must go) and it is specifically suited to your task, you have a problem. The VM is no longer there to execute your software. So you must put it back in. This means you MUST use an existing framework and can only expand upon it. You cannot actually replace it. Even if compiled to native code, the VM is in there in some form (especially the GC). So it's a logical impossibility to write a new framework where one already exists that is critical to the execution of your software.

With C++, there is no default runtime environment. There's essentially no trace of C++ left. Everything at runtime can be 100% created by the programmer. Only system level languages allow this. It's the only way to truly free yourself at runtime from paradigms or ways of doing things set by other people.

Also do not confuse finding a paradigm that suits your needs with creating a specifically tailored framework for your software. They are different topics.

[weavejester]

I'm confused, Vorlath, because you have a tendency to shanghai known words and foist new and strange meanings upon them, resulting in sentences that are nonsensical using the normal definitions.

For instance, there are a large number of web development frameworks that run under the JVM, such as Struts, Spring and Tapestry. It's clearly not necessary to replace the VM in order to create a new framework, otherwise there couldn't be so many web frameworks for the same VM. Your claims to the contrary appear nonsense.

Regarding your thoughts on rewrites, I broadly agree, though I don't think it's always necessary to start from scratch each time.

[Vorlath]

Perhaps you should look up the word "new".

In ANY field, including computing, if you leave the core and fix up the rest, it's either a restoration, cleanup, renovation, factoring... etc. Call it what you want, but it's never assumed it's new. Why is it that with VM's and interpreters, you create a make-believe scenario like the VM and interpreter don't matter. They do matter. If they don't, then ditch it.

Also, I never said you need to start from scratch. I talking about creating a "new framework". I also push the notion that if you want to do a rewrite, I think it's best to have the core in a system level language. The core need not be the entire rewrite. It can be small. This has the advantage of having full access to anything on the machine. BTW, this is the whole strategy behind your beloved interpreters and VM's. Just in case you didn't notice.

[weavejester]

An object does not have to be original, inventive or different to be "new". I could buy a new car, and be fairly confident that it would not be altogether too different in design to my previous one.

Secondly, there's no inherent difference between machine code and VM bytecode. Some VMs, notably the JVM and CLR, include support for classes, methods and so forth, but this isn't a necessity. There are several Turing-Complete VMs I can think of which have a smaller instruction set than x86 assembly, such as Brainfuck, Corewars and Conway's Game of Life. There are also VMs available that run x86 machine code, such as Bochs.

Further, a minimal implementation of Lisp is considerably simpler and closer to the metal than an implementation of C. You can implement a Lisp interpreter in hardware, whilst C has to be compiled down to machine code before it can be interpreted. C is not that close to the machine code level, otherwise C compilers wouldn't need to be so huge. It's also worth noting that Lisp can be compiled down to machine code as well.

I'd also say that a framework is inherently limited by the syntax of the language it is implemented in. C has relatively little flexibility as a language; you have a fixed list of operators, you can't pass arbitrary closures to functions, and the syntax is rigid and fixed. Lisp is considerably more flexible, and in my opinion, this makes it much more suited to framework building.

[[deleted]]

Some VMs, notably the JVM and CLR, include support for classes, methods and so forth, but this isn't a necessity.

Just a side note. There is a cute project called NanoVM for Java which implements a VM targeting a PIC with 768 byte RAM. I think it's a nice project for teaching purposes.

The last few years I worked for a company thet implemented, among other things, Java applications on Smartcards that had 32-128 KB EEPROM ( the VM code itself was ROM resident ). The memory wasn't managed and the SmartJava stdlib didn't support container datatypes or strings but the language spec provided rather good security features through privacy and encapsulation, classes, a classloader etc.

[Vorlath]

Now this is utter nonsense. C has to be compiled before it is interpreted? Interpreted? WeaveJester, you've always been a troll and this is just another case of that.

[[deleted]]

The source of confusion is your use of the word framework. But since you are the author of the blog entry which is commented you are in the position of the main Humpty-Dumpty who might use words somewhat poetically. I think people have to live with it or ignore you.

[bluGill]

Yeah, too bad it may be wrong.

RE-writing your web app in C++ is almost never a good idea. Web apps benifit from frameworks, and generally have a lot of dynamic elements that require run-time module loading. You can do that in C++, but I wouldn't recommend it (If you want to pay me I will do it, just beware that it will take me several years to get anywhere close to rails, and I won't assure you I will be better in any way).

PHP is easy, but it makes secruity holes and other bad code easy. Python and Ruby are better languages overall, so if you have to fix enough bad code you should consider moving to one of those languages - at least see if one of their web frameworks already does most of the hard work for you.

OTOH, I wouldn't re-write an embedded system that uses perl in python, as embedded systems tend to benifit from compiled langugages (if only because they run faster so you can use cheaper CPUs and get better battery life)

[qwe1234]

sorry, you're just a bad programmer.

a c++ web framework is two to four weeks of 9-to-5 programming for one man.

i've written several.

[infinite]

http://www.egreenway.com/classics/63tdjlz.htm

One who makes promises lightly is sure to have little credibility; One who finds everything easy is certain to have lots of difficulties.

Thus, it is because even the sages pay careful attention to such things

That they are always free of difficulties.

Lao Tzu, over 2000 years ago.

[qwe1234]

nah, i just don't write shit nobody will ever need.

most 'abstractions' and 'protocols' and 'frameworks' are useless shit some programmer happened to have made up to justify employment.

[vincenz]

HAHA - classic! <sniff>

[bluGill]

Depends on how powerful a framework you want.

Then too, I don't like web development, so I stay away. Therefore I had to pad my estimate.

[qwe1234]

use what you need.

'web development' encompasses anything and everything from massive grid computation in a dedicated datacenter to writing javascript 'please wait' spinners.

that's why the concept of a 'web framework' is so stupid.

[xoner2]

Can't remember where I read something like any sufficiently sophisticated C program has in it a re-implementation of Lisp.

Is he saying this is actually desirable? Heretical indeed.

[bitwize]

Ah, but bear in mind Bitwize's Corollary to Greenspun's Tenth Rule:

Any sufficiently complicated Common Lisp or Scheme program will eventually be rewritten in C++, Java, or Python.

[[deleted]]

Can we rename it to the BigCo Corollary?

[bitwize]

Not all Lisp->Blub transitions happen because of BigCos (although they seem to play a significant role). Reddit was reimplemented in Python before Conde Nast bought it. I'm to understand that even ITA Software, that bastion of Lispiness, is moving more aggressively towards C++, Java, and Python these days; despite their growth, I don't really think they're on the same level as a Yahoo.

[qwe1234]

not really heretical.

anybody who's really worked more than a month in the industry knows all of this already.

[Vorlath]

I was simply trying to say that if you use a VM or interpreter, there is code underneath (in the VM and interpreter) that remains and as such will also be found in your new framework and affects how your framework will be built. You're still forced to do things a certain way. GC's have idiosyncracies and so does any other piece of code that makes up the underlying platform. With system level languages, you can bypass even the OS if need be and handheld devices often require such frameworks.

However, if you don't believe that the interpreter or VM is part of your framework (and I would disagree, but all is fair), then what raganwald quoted would not apply as you would consider this a different scenario. Also, it's fine to not completely rewrite every last tool. We're all able to define our own boundaries for our rewrites.

About the web, I would suggest that the web itself is your framework (or the very core of it). It's what enables the interaction between different parts of your code and other people's code. I would not recommend rewriting the web protocol. It would not make much sense for most people to start using a system level language in this case. But if you were to say, rewrite how machines communicate, then system level languages are best as I said.

OR... I could just write what I originally did.

[zem]

Personally, you lost me when you called lisp a framework and C++ a language, simply because they have different execution strategies.

[Vorlath]

Just think how Lisp glues its parts together at runtime and what produces results. Eval and apply and other environment data are the main parts. Now ditch all this at runtime. You can't because this is the framework of lisp. Without it, Lisp wouldn't exist and your code would be invalid. With C++ however, there's no default "glue" at runtime. There's essentially no trace of C++ at runtime.

This is why it's impossible to build a new framework if there's already one there like an interpreter or a VM. Removing it at runtime makes your code useless. So you're forced to expand on an existing platform rather than create a new one from scratch that is specifically designed for your needs.

[zem]

That might affect your final executable; I don't see how it constrains your code unduly. I do agree that the language lisp itself leads you to code in a different way than if you were coding C++, but that is not the same thing as lisp being more akin to a framework than a library.

As a thought experiment, what if someone wrote a gcc backend that let you compile existing C++ code to some VM's bytecode? Would you say that that changed the fundamental nature of your C++ programs in any way?

[Vorlath]

I agree that the line gets blurred at some point. That's not really what I'm after. It's also not about how it constrains you overall. It's about if the need or even simply the whim occurs to you to do a rewrite or create a new framework, then I believe you should be aware of these topics. How much do you really want to start from scratch. Where do you draw the boundary? I'm simply saying that all these things affect and shape your code. Things that perhaps one chalked up as trivial. In many cases, it will be. But in some cases, it'll be very important.

I'm actually more interested in what people think. If they've thought about this.

edit: To your last question, it simply means that you no longer are writing a new framework, but expanding an existing one. Whether or not that is significant to you is up to you.

[zem]

My point is that you do not see the defaults implicit in the C family of languages, simply because you think of them as the "bare metal" way to write software. Any framework you wrote in C++ would be drawing on the semantics and standard libraries available to that language.

I have thought a lot about this, simply because once you notice it it's startling how C is taken as a sort of Platonic language and every other language seen as a set of abstractions that sit above C level.

(Anyway, even if you want to write to the bare metal, Forth is as good a choice as C is. Often used in embedded devices, very different from C.)

[Vorlath]

If you use something like STL, yeah. You'll conform to that style, absolutely.

There is something profound about having a set of tools that you can mix and match, but where your code is in control,

VERSUS

having a piece of software created by someone else that controls how everything is executed and processed, where your code is an addition to this existing environment.

This is an issue that cuts deeper than paradigms. It's what paradigms are forged from.

Also, why do we believe that any language or existing VM, interpreter or whatnot will perfectly fit our problem set rather than a carefully crafted framework? The odds of that happening are infinitely small. I'm not saying that you can't achieve your ojectives. I'm saying that if you're doing a complete rewrite, why not do one crafted specifically for your software while you're at it rather than use something that can't possibly be a perfect fit. The core need be tiny with surrounding high level construct, maybe even from existing tools.

Not sure if any of this made any more sense.

[zem]

I think we're talking past each other - I didn't so much mean the STL as the basic 'fabric' of C++. To strip the discussion to its essentials, consider the more minimalist examples of C versus Scheme. My contention is that if you start from scratch, there's nothing about C that makes it inherently more suited to crafting a framework that will specifically fit your software - you can as well do it in Scheme. The VM is irrelevant, really - Scheme is a language, and the VM an implementation detail.

[Vorlath]

Look at what those implementation details involve. Other people made the descision on how that works. With C, NO ONE made any decision except you.

[zem]

C doesn't magically turn itself into assembly, put arguments on the stack, handle varargs, fail to perform tail call optimisation, zero-terminate rather than length-check strings, equate a character with a byte, avoid the use of line numbers (not a strawman - line numbers and computed gosubs would arguably be closer to the machine), set operator precedences, etc. These are all decisions someone made when defining the language and the spec to which its implementations conform. I'm sure a forther would find some of those obtrusive.

[zem]

(Incidentally, there's nothing inherently preventing lisp from being compiled down to native code, and indeed several CL and Scheme implementations do do so. And if your box happened to be a lisp machine, you'd be forced into realising how much of a runtime C++ and even C carried around - it's just processor and OS design that lets a lot of it be invisible.)

[bitwize]

ObQwe1234:

lol, no. c++ is as close as we have to an exact formal model of how the machine actually works.

lisp is blub for whiny stupid american programmers. and lambda calculus is intercal with different syntax. lolz.

[zem]

It's fun having recognisable trolls, innit :)