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Favorite Programming Language Features? 312

johnnyb asks: "I'm curious what everyone's favorite programming language features are. I'm looking for both the general and the specific. I'm especially looking for features that few people know about or use, but are really useful for those who do know about them. What are your favorite programming language features?"
"A couple of examples to kick off the conversation:
  • Continuations

    Continuations are very interesting, because they can be used to implement a number of flow-control features such as exceptions, coroutines, cooperative multithreading, and are better at modelling web interactions. This is a more general feature, but most people use these in conjunction with either scheme or ML.

  • Tuple-returning

    It is a huuuuge time-saver when languages like Perl allow functions to return tuples. Instructions like '($a, $b, $c) = $sth->fetchrow_array()' is a wonderful thing.

  • The flip-flop operator [Perl's '..' operator]

    Another perlism that I just think is cool. Read more about it here.

Okay, on to yours!"
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Favorite Programming Language Features?

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  • Simple, OOP (Score:3, Insightful)

    by agent dero ( 680753 ) on Wednesday July 07, 2004 @07:16PM (#9637573) Homepage
    Object-oriented programming.

    For me it's just easier. ;)

    (Especially with XCode displaying it as a little blue box, it makes the concept easier to grasp for beginners)
  • That's obvious (Score:2, Insightful)

    by krel ( 588588 )
    Beautiful syntactical simplicity.
    *cough*C*cough*
    • I **LOVE** Curly braces! Gotta have 'em!
    • The computed goto is great.

      void *vp;
      some_label:
      vp = & // the unary && operator
      goto *(vp);

      Oh yeah... fill a jump table with pointers and
      you can do some pretty cool stuff.

      Let's not forget __asm__ with automatic register
      assignment, the ability to place a variable into
      a specific section of the executable, the ability
      to associate a variable with a specific register,
      the __builtin_expect and __builtin_constant_p
      builtins... gcc kicks ass.
      • I didn't ask for HTML. I chose plain text and I
        damn well expect Slashdot to accept full ASCII.
        I'll try "Code" now. Grrr.

        void *vp;
        some_label:
        vp = &&some_label; // the unary && operator
        goto *(vp);
  • (void *)(void *);
  • by Anonymous Coward
    j/k
  • Tcl and Postscript both offer lists and lists within lists, without having to do anything fancy. Perl does have this, to an extent, but only on static lists. Anything dynamic adds a few lines of code and confuses things pretty easily. Of course, all of this came from Lisp, but I learned car and cdr and that was more than enough for me.

    In short, lists only work when recursion is right at the tip of your fingertips in your language. If XSLT-2.0 works on tree fragments, we will have lists there as well.

    • Re:Lists (Score:3, Informative)

      Perl does have this, to an extent, but only on static lists.

      What do you mean by 'static lists'? Do you mean they're immutable?

      You can do
      push(@{$outer[$inner]},$value)
      to add to a list in a list. The syntax is tough, but I think it does what you mean. @{} is like a cast-to-list.
      man perlref
      should be helpful.
      • What do you mean by 'static lists'?

        I would guess he means "lists that are hardcoded into the program", I forget the proper term for this.

        He was saying that perl creates nested arrays nicely:

        my @array = (["foo", "bar"], ["baz", "qux"]);

        But when it comes to actually creating a structure like that dynamically using push or unshift, the code gets really ugly. And I think you proved his point ;)

        • Just to clarify, the above code snippet creates a two-dimensional array, it could also be created thusly:

          my @array;
          $array[0][0] = "foo";
          $array[0][1] = "bar";
          $array[1][0] = "baz";
          $array[1][1] = "qux";
  • by notyou2 ( 202944 ) on Wednesday July 07, 2004 @07:30PM (#9637672) Homepage
    I think's java's concept of anonymous inner classes is simply superb... it enables runtime aggregation of small objects while preventing you from having to create hundreds of named external helper classes to implement the behavior.

    It's certainly not an unknown feature, but I couldn't live without it.
    • I absolutely hate anonymous classes. They make for some really ugly code. Private classes seem much simpler to me.
    • Other programming languages do this so much better with different constructs. For example, "blocks" in Smalltalk, Ruby, or "currying" in ML, etc.

      Java's inner classes (anonymous or named) are not even first class! (Try coding an inner class that refers to a non-final attribute in its enclosing scope.)

      They are better than nothing though ...

      • by Bazzargh ( 39195 ) on Thursday July 08, 2004 @04:27AM (#9640203)
        Java's inner classes (anonymous or named) are not even first class! (Try coding an inner class that refers to a non-final attribute in its enclosing scope.)

        This isn't quite right. First off, they are first class [c2.com], and you can refer to a non-final attribute from a named or anonymous inner class. What you can't do is refer to a non-final local variable from an anonymous inner class.

        The intended effect is similar to closures - variables referenced from the enclosing scope have the value when the closure was instantiated (see, e.g. Scheme) - except that unlike scheme, you can't modify the now-private copy. If you want a modifiable copy, you just make one, like so:

        final finalFoo = foo; Object bar = new Object() { private myFoo = finalFoo; // myFoo now acts as 'foo' would if this was // *really* a closure. }

        I'd agree that the construct sucks. I'd rather be in a language with closures myself.

  • Many (Score:5, Interesting)

    by Apreche ( 239272 ) on Wednesday July 07, 2004 @07:37PM (#9637712) Homepage Journal
    First off I like nothing more than automatic memory management. Being able to forget about pointers and malloc and all that garbage makes programming infinitely easier and faster. I only write in C or assembly when I really really need the speed or when I'm at such a low level that nothing else is possible.

    Next I love ruby's block system, especially for stuff like this.
    myarray.each { |e| puts e }
    It comes in super handy for a ton of stuff. Especially when I'm doing XML.

    Also, there is another thing that I first discovered in python
    x, y = y, x
    Save me a temporary variable, w00t.

    Lastly, its not really a language feature, but in any object oriented language I love being able to serialize the objects. It's so simple to use pickle or any other serialization library and just write objects out to file or network. I never have to design a binary file format ever again. It's even better when you use Ruby and you can marshall objects into XML or YAML with a single method. Then you've got a human readable and editable file format that you can magically transform into objects again later. Super useful.
  • Dreamed-of feature (Score:5, Interesting)

    by Dr. Weird ( 566938 ) on Wednesday July 07, 2004 @07:39PM (#9637729)
    This is less of a favorite feature, and more of a feature I wish we had. What about having the representation of the language independent of the code itself? I think this will eventually happen and could really revolutionize things. I believe the inklings of separating 'physical' representation from the code were there in some languages like Algol 60 and CS work in the 1960's, but it never caught on (perhaps hindered by other features of those works?).

    In a little more detail, suppose I write a C program. It will have lots of functions and conditionals with their "blocks" surrounded by braces.

    But what if I prefer my "blocks" to be started and ended by brackets instead of braces. Better yet, what if I am tired of typing these and would like indentation to control this. Or whatever -- start end commands, if you like. The point is that these are minor sytactic idiosyncracies, and we all have preferences. Why not store the code in an underlying format (XML would be okay, were it not for the bulk of it)? As long as there is a one-to-one correspondence between all possible representations, you could view it however you want.

    And so on for all syntactic features. Prefer "if-fi" construction to "if () {}"? Or "if ... then ..."? Better yet, really like Perl's "$_"? If you want it to be displayed like this, turn it on. Otherwise, say you don't like this feature, and it will automatically replace the "$_"'s (either implicit or explicit) with the variable to which it refers. Again, no problem.

    At this point, I feel like I am repeating myself, but let me continue for a little bit. It would let each user have his/her personal favorite representation. We already let them control the colors of their syntax highlighting, lets take it a step further.

    Hell, if you want to use a graphical viewer for those C programs, akin to LabView, go for it! Or (in my opinion) a much better graphical programming environment with a graph structure. The point is: you write it how you want and save it. It appears to another coder how he/she wants it to appear, but the content is exactly the same.

    In short: why isn't this done? It seems like a spectacular step in unifying programming languages a bit, and letting each user tailor his preferences while maintaining compatibility. As long as there was simple one-to-one correspondence, the translation from physical representation to underlying code and back would be quick and fairly easy to handle. Are there any modern projects which attempt this? Or *any* which attempt it with some success?

    On a somewhat related note, is it possible to put a "hook" to a comment in the code, and with the proper viewer have that comment displayed along with the code (say when you click the "hook", move your mouse over it, or drag the "hook" to a "comment box")? If this last paragraph doesn't make sense, please ignore it.
    • This is a terrible idea for maintenance. Imagine trying to read the code for a given app that had all sorts of bizarre preferences chosen. You would have to spend a lot of time just understanding what the hell you were looking at.

      The whole idea is to make things as uniform and regular as possible because then there is less for everyone else to learn when they look at the code. This suggestion adds a whole layer of confusion, and only buys a modicum of user preference in return. That is a poor tradeoff.
      • Imagine trying to read the code for a given app that had all sorts of bizarre preferences chosen. You would have to spend a lot of time just understanding what the hell you were looking at.

        No. In some sense, this is precisely the problem I try to avoid. The bizarre preferences were chosen because that programmer/company/standards bureau liked them and/or found them useful (hopefully). By storing the content of the program, and not their silly display preferences, it would load and present to me

        • By storing the content of the program, and not their silly display preferences, it would load and present to me however I had it set up to display it, not according to their preferences.

          One of the obvious benefits is the end of the holy wars over brace and indentation style [catb.org]. Think code should be tabbed out 2 spaces instead of 4? Constantly resisting the urge to reformat everyone else's Java code to 1TBS? Want to program in C using Python-style meaningful whitespace? Not a problem. Just clicky-c

          • What you are describing is a IDE feature, not a programming language feature. Or alternatively, it is a programming language feature that forces everyone to use a whizzo (read memory hungry, buggy, etc) IDE. No thanks.

            One of the obvious benefits is the end of the holy wars over brace and indentation style.

            Good project managers don't allow coding style holy wars to break out. They mandate a house coding style, and (if necessary) use code reviews to enforce it.

      • This is a terrible idea for maintenance. Imagine trying to read the code for a given app that had all sorts of bizarre preferences chosen. You would have to spend a lot of time just understanding what the hell you were looking at.

        I don't believe that you understand the concept becuase it seems that your argument doesn't apply.

        The whole point would be that you wouldn't see the idiosyncrasies of the way that he likes his code laid out, he would in essence give you compiled code and your development e

    • You could do this in perl if you wanted to. For instance, you can code perl in Latin [cpan.org]. It's done using the Filter::Util::Call [cpan.org] module, which lets you preprocess your perl code. Read Damian Conway's discussion [yetanother.org] about it. He gives a simple example using Klingon keywords and talks about implementing a Switch function in perl.
    • But what if I prefer my "blocks" to be started and ended by brackets instead of braces. Better yet, what if I am tired of typing these and would like indentation to control this. Or whatever -- start end commands, if you like. The point is that these are minor sytactic idiosyncracies, and we all have preferences. Why not store the code in an underlying format (XML would be okay, were it not for the bulk of it)? As long as there is a one-to-one correspondence between all possible representations, you could

    • by wayne606 ( 211893 ) on Wednesday July 07, 2004 @11:27PM (#9639123)
      Why in the world would any programmer care about whether they write "if { }" or "if ... fi", etc? I don't see the big advantage in indulging one's personal preferences about syntax. It's not like every person's brain has a completely different way of reading a program that makes it significantly easier to understand a unique brand of syntactic sugar...

      Sure, you can develop in your own special IDE that gives you your unique syntax. But don't you ever look at code together with other programmers who might have different preferences? Don't you ever view code published in magazines and on web sites that can't pretty-print to your specification? Training yourself to strongly prefer some kind of private language is not a very good idea.
    • If I did that, no one would be able to help me if I get something wrong - e.g. I screwed up in my custom syntax or metadata or my code, and I'm not sure where.

      And it would be harder for me to learn from other programmers programs and integrate their code.

      Ultrageniuses and Uber Programmers are free to write their whole entire universe of code, but I bet crappy programmers like me will still stick to using what tons of people are using, and reusing other people's work (e.g. CPAN) and learning from _their_mi
    • I have to say, I've been thinking of this myself, but always assumed there was a good reason not to do it and that I was being stupid for thinking it.

      This has given more confidence now that obviously intelligent people are also thinking it.

      The only real problem I can see with it is that if you didn't have an IDE available (you needed to hack a piece of code in notepad or something) you probably wouldn't understand the code, or at least, wouldn't be used to it.

      With the size of code these days, though, it'
    • I agree. But more so.

      We use graphical interfaces for a lot of things, we should use them for programming.

      SCREW the text editor based programming.

      What is this bracket crap to seperate codes?

      You want to seperate code? draw a circle around it. Variables that are in the circle can be accesed by code in the circle. Want to reference a variable outside the circle? Draw a line from it into the circle. And guess what - you can tell from the color of the variable name that it is not from that same object.

      • by Anonymous Brave Guy ( 457657 ) on Friday July 09, 2004 @07:16PM (#9657840)
        We use graphical interfaces for a lot of things, we should use them for programming.

        SCREW the text editor based programming.

        I think this is one of those rites of passage all experienced programmers probably go through. At some stage, your experience of different languages gets to the point where you understand that the underlying concepts transcend the syntax of any specific language. A natural next step, particularly if you've seen the sort of parsing graphs used by compilers, is to assume that throwing out the "awkward" text syntax in favour of some whizzy graphical scheme will make things much easier. Some people have even done PhDs on this subject.

        Unfortunately, when you try it in practice, you find it's not nearly as clear-cut as you thought. Like all that nasty, unnecessary punctuation found in many programming languages, it turns out that using a concise, precise text format is often far easier both to read and write than any graphical alternative. What can be done in one line of regex in Perl takes a whole screen of graphical representation via flow charts and state machines.

        I wish you luck in your exploration of graphical alternatives, but I'm afraid the odds are pretty heavily that after a while, you'll come full circle, and understand that all that nasty "bracket crap" is there for a reason, and has survived for decades because that reason is sound.

  • Perl (Score:2, Flamebait)

    by psyconaut ( 228947 )
    Write once, read never ;-)

    -psy
  • MS C++ when it auto-fucks inline assembler!

    Wow, I coded a JMP there, somehow its now a JNE. Hmmmmmmmm... How'd I figure that out? Deadlist on a compiled executible. Never NEVER told me it'd do that. Just did it. Almost as bad as MASM...

    Sucks having to compensate for compiler errors!
  • by Breakerofthings ( 321914 ) on Wednesday July 07, 2004 @07:57PM (#9637835)
    Closures and Currying are two of my personal favorites.

    Overloaded Functions are sweet.

    I am also quite fond of operator overloading.
  • Favourites (Score:4, Insightful)

    by E_elven ( 600520 ) on Wednesday July 07, 2004 @08:00PM (#9637859) Journal
    Ruby blocks, lambda functions, lazy evaluation.

    And C++ :)
  • I like lots of things from different languages..

    regexp functions -> functions that do what the regexp do. eg result = regexp.removeSpace(word);

    Easy to understand syntax.. instead of && use AND, instead of OR use OR, etc. kinda BASICish syntax.

    Garbage collection that works, unlike java where sometimes it losses things, because of programmer error. IE: if I can do it the garbage collector should clean up after me, if it can't then it should not let me do it.

    Definatly object oriented, Java / C

  • by Quill_28 ( 553921 ) on Wednesday July 07, 2004 @08:06PM (#9637892) Journal
    Just to confuse people do this:

    main() {

    int x;
    int y[2];

    x=1;
    y[1]=10;

    printf("%d\n", y[x]);
    printf("%d\n", x[y]);
    }

    What will happen?
    • by ComputerSlicer23 ( 516509 ) on Wednesday July 07, 2004 @08:31PM (#9638051)
      As I recall, in C x[y] and y[x] are defined to be identical. I believe you can do 1[y] and have it work. That's because a[b] is must be identical to *((a) + (b)). I'm over using paranthesis intentional. Because addition of a pointer and a constant is communitive, either one works. Because (1 + y) is a legal, and returns a pointer it works.

      Personally, I think it's a completely crappy thing. You should get an error telling you: "Attempting to use a constant like a pointer".

      So it should print out "10\n10\n";

      If that's an ANSI C complier: you should get a warning about no return in main, an illegal declaration of main, and an unknown function printf. You might get away with main, because I believe all functions implicitly return an int.

      Kirby

    • by Chemisor ( 97276 ) on Thursday July 08, 2004 @08:39AM (#9641433)
      Just because you can write it that way, does not mean you should. Should you blame makers of underware for letting you put it on over your clothes? Just because Superman can do it, does not mean you should.
  • Self-execution (Score:5, Informative)

    by BollocksToThis ( 595411 ) on Wednesday July 07, 2004 @08:08PM (#9637911) Journal
    My favourite thing is languages that can execute strings of their own code.

    For example, clipper can do this via blocks:

    cVar := &("{ || nVar += 43")

    Python has the same thing via "exec":

    >>> b
    NameError: name 'b' is not defined
    >>> exec "b=2"
    >>> b
    2

    This means you can build up strings of code at runtime and execute them, or store field-specific database logic in another database table, and fetch it when needed.

    C# is not quite so convenient - you have to build up a complete class and compile it, but it can all be done in memory at runtime so it's just a little more work. Clipper and python can both affect the current scope directly (which can be both bad or good, I suppose).

    I believe ruby has blocks similar to clipper (probably better), but I don't use it, so I'm not sure. I also don't use perl, so I have no idea if it supports this...
    • Hmm... I have yet to see a valid reason why runtime code generation might be valid. Would you care to supply one? I'm honestly interested; I see no real point, but I'd like to.
      • I'm not sure what you mean by 'valid', but I'm going to go with 'useful'.

        Say you have a database with multiple tables that all require user data entry. You can write code for each and every data entry screen (apparently the "visual basic" school of thought), or you can write a generic data-entry screen and include pieces of code for specific field validation in the database itself - so in effect, based on structural tables, the program builds the correct code for each screen. This also saves having to di
      • So that a remote attacker can cause a system to run arbitrary code of the attacker's choice.

        Very useful when you need to do things that the system was never designed to do.

        Whole industries and many thousands of jobs depend on such useful ideas. :).
  • Several: (Score:3, Interesting)

    by twem2 ( 598638 ) on Wednesday July 07, 2004 @08:13PM (#9637935) Journal
    Functions as first class citizens, that is functions can be returned from functions and provided as arguments as functions. The basis of the functional paradigm and it makes life much much simpler.
    Pattern matching (some ML:)

    fun has_a [] = false
    | has_a 'a'::_ = true
    | has_a _::xs = has_a xs;

    Simple elegent functions requireing much less if_then_else's.

    Automatic garbage collection and bounds checking: enables me to write the code to do the job, not the memory management.

    Polymorphic typing: I can write general functions:

    fun contains x [] = false
    | contains x x::_ = true
    | contains x _::xs = contains xs;

    That will work with any type for which equality is defined.

    These are the reasons I hate C for general programming. The most important thing is efficient algorithms, without them no amount of low level optimization will help. With good algorithms, functional languages are now normally at least as fast... (and much much easier to debug and even verifiable).

    From non-functional languages, the object model is wonderful when used properly.
    Smalltalk & co's complete environment is a nice feature.

    I also have a soft spot for BBC BASIC with its speed, interactivity and simplicity. These are combined to allow windowed applications including at least one web browser and anyone can start programming simple programs (which is missing from most modern computers)

    Then there's the specialist languages. They have all sorts of nifty features (Mathematica is a good example) but I wouldn't expect them in an everyday language.
  • by Fished ( 574624 ) <amphigory.gmail@com> on Wednesday July 07, 2004 @08:19PM (#9637973)
    This is not the issue it was ten years ago, but one feature I absolutely want tightly integrated into my language is robust string handling. I still like perl's best (although perhaps only because I know it best). It simply seems to be more tightly integrated into the language as a whole.
    • I'd like to second this. In fact, I'd have firsted it if you hadn't posted.

      Strings are one of the most important aspects of programming; the number of complete, useful programs that have been written that didn't process or use a string in some way is close to zero.

      A good programming language uses and processes strings in a speedy, efficient manner, and has a robust, easy to program means of doing so.
    • This is certainly true to a point. There are three basic kinds of data used throughout the programming world: text, numbers and logic (true/false). Pretty much any mainstream general-purpose language provides basic arithmetic and logical operators, and then an extensive library of more advanced mathematics functions. With strings, you often get basic operators, but beyond those there's a world of difference between providing a couple of upper-/lower-case conversions and having things like regular expression

  • by Paul Bain ( 9907 ) <paulbain@NoSpam.pobox.com> on Wednesday July 07, 2004 @08:26PM (#9638013)
    The poster, johnnyb, also asked this question on Advogato [advogato.org] just a short time ago. It will be interesting to see the differences in the comments made there and the ones made here at Slashdot.

    Hey, johnnyb, where else have you posted this question? When you get answers, will you analyze them and post your conclusions? It could be interesting.

    • Actually what I'm wanting to do, eventually, is write a book about great programming constructs people have probably never heard of, or don't understand well.

      My last book [cafeshops.com] took me 3 years to find the spare time to finish, so I don't suspect I'll have this done anytime soon.

      I was originally going to just analyze scheme's features, but then I realized that many languages have features that need to be recognized, too. my original outline was going to be:

      * Memory Management
      * Symbolic programming - an intro to Scheme
      * Functional Programming & Functional Programming Patterns
      * Closures and higher-order functions
      * Advanced Flow Control w/ Continuations
      * Compile-Time programming 1: Macros
      * Compile-Time programming 2: Partial Evaluation
      * Compile-Time programming 3: C++ templates
      * Lazy evaluation
      * Lazy data structures

      However, if I decide to open it up to other languages, I have no idea how I'm going to organize it or even how I will decide what to include.

      Anyway, it was originally posted just to Advogato, but then I remembered that the only threads on Advogato that get any real response are flame-wars, which is sad because Advogato could be a real cool place. Then I thought "you know, this would make a good 'Ask Slashdot' as well. However, I don't expect the quality of responses on Ask Slashdot to be as good, although I expect there to be a LOT more of them.
  • by mkcmkc ( 197982 ) * on Wednesday July 07, 2004 @08:29PM (#9638032)
    Like probably most people, I hated Python's blocking-by-indentation syntax for the first few weeks. The column restrictions kind of reminded me of FORTRAN.

    But after the adjustment, I've truly grown to love its spartan clarity and simplicity. I can hardly stand to look at the redundant brace-littered syntax of Java, C or Perl now.

    Mike

    • Complete agreement! It's much easier and readable. It would be great if MS used that for Visual Basic, instead of the ugly End If construct. Much more comfortable for people who have to work with VB every once and a while. Some people get too attached to the English language.
  • by LoveMe2Times ( 416048 ) on Wednesday July 07, 2004 @08:31PM (#9638050) Homepage Journal
    The ability to do generic programming ala Boost [boost.org] is a great feature. Higher level languages are all about better abstractions, and generic programming is the best abstraction mechanism we've seen in general use since OOP. While OOP lets you encapsulate behavior and abstract over interfaces, generic programming lets you abstract over *form*. The significance is in the coupling. Generic programming allows much looser coupling between the writer of the generic library and the user of the library. A nice example is a generic "find" function:
    template <typename I, typename V>
    I find(I begin, I end, V val)
    {
    for (I it = begin; it != end; ++it)
    if (*it == val)
    return it;

    return end;
    }
    And here, you have captured the essence of a linear search. To understand what's going on, first know that I and V are arbitrary types that are inferred (at compile time) from the values you pass when you actually call the find function. For the generic find function to work, there are only a couple of restrictions on these types:

    1) I must be incrementable.
    2) I must be dereferenceable.
    3) You must get from begin to end in a finite number of steps.
    4) The type you get when dereferencing I (I's value type) must be comparable to V.

    Because of this, you can use the same find function to search through arrays, lists, vectors, maps, sets, strings, streams, and more, even though none of them inherit from each other or implement a common interface in the OOP sense.

    Additionally, there's no complicated syntax for the user of the library:
    int myarray[10] = {1, 1, 2, 3, 5, 8, 13, 21, 34, 55};
    int* p = find(myarray, myarray + 10, 8);
    if (p == myarray + 10)
    cout << "8 was not found." << endl;
    else
    cout << "The value of p is " << *p &lt&lt "." << endl;
    The great thing about abstraction is that it avoids duplication. Avoiding duplication lets you test/debug/prove correct once for greater reliability. Once you wrap your head around this simple example, you'll be surprised how deep the rabbit hole goes.

    • A nice example is a generic "find" function

      Remember the Swedish rock group ABBA? How many instances of the substring ABBA occur in the following string [and what should your generic "find" function have as a return value]?

      ABBABBA

      Extra Credit: Tell me what a generic "replace" function should do when told to replace "ABBA" with "The Bee Gees".

      PS: I learned just the other night that ABBA soloist Anni-Frid Lyngstad was the product of Nazi Aryan eugenics experiment [dubbed "the Lebensborn"].

      I excremen

    • One thing I've always wondered (since I mostly do C and not much into C++), how is this different than something like pointers to void in C? For example, the way qsort() works -- it can operate on any data type also.
      • Generic programming is in many ways kind of the opposite of using void*. Using void* your world is typeless. With generics, you have the full type information available to you. Generic programming is very much about Type Theory.

        This plays itself out in many ways. For starters, with generics you can do specialization (like for your sort example, you might want to handle things differently depending on whether your void* points into an array vs. a linked list vs. a b-tree). You also have no problem doing thi
  • I use Common Lisp.

    Lisp has almost no syntax, so it's extremely regular (barring exceptions like LOOP). Because it's so regular, it's easy to build macros that do powerful things.

    Macros can completely transform the source, at compile time, but with the full power of the language. Having that ability, together with simplicity, means that it's easy to build a complete mini-language for one's manager or web designer to use on the site, and easy for them to learn it, since you can explain the syntax in 5 mi
  • my favorite (Score:3, Insightful)

    by scrytch ( 9198 ) <chuck@myrealbox.com> on Wednesday July 07, 2004 @08:51PM (#9638158)
    Clean syntax. Not one that forces me to lean on my shift key and decorate my code with punctuation characters. The "noise" gets in my way so much that I can't even stand to program in perl anymore. I just can't take syntax like sub foo { dostuff @{$blah->{woof}}; etc... } anymore. Semicolons drive me bats.

    Python's ok. Tcl is closer to the ideal syntax, but oy what a feature poor language. Lisp's really nice. Forth would be about perfect, but it makes you work at such a low level most of the time (fact is, most people just don't build it up that much) that your code looks noisier than perl, more like APL even.

    Of course I like modern features, like automatic memory management, structured exceptions, first class functions, pattern matching, currying, asynchronous execution, concurrency, and so on. But I just can't express concepts well in a language that makes me clad every expression in so much syntactic scaffolding.
    • Incidentally, Haskell is probably my favorite in terms of clean syntax and language power. It just requires a PhD to manage to write anything more complex than "Hello World". The compiler's speed is also best described as "geological".

      Ocaml is much more "real world" (you can even have variables (*gasp*)!) , but ocaml is full of syntax warts, unhelpful compiler feedback, a module system that's *supposed* to be the bees knees but looks suspiciously instead like plain old namespaces of static methods, and w
  • Perl's taint mode (Score:5, Interesting)

    by babbage ( 61057 ) <cdevers@cis.usou[ ]l.edu ['tha' in gap]> on Wednesday July 07, 2004 @08:58PM (#9638188) Homepage Journal
    In the current issue of ACM Queue [acmqueue.org], Marcus Ranum makes an interesting case for Perl's taint mode in his article Security: The root of the problem -- Why is it we can't seem to produce secure, high-quality code? [acmqueue.org]:
    Right now, the state of the art in software security is to pass your code through some kind of static source-code analyzer such as ITS4 or Fortify that looks for dangerous practices and known bugs. That's a great start, and, according to my friend Gary McGraw--chief technology officer of Cigital and author of several books on software security--who works with the stuff, it catches a significant number of potential security problems. But, as you can see, the compiler already knows a lot of what it needs to in order to make a good stab at determining what is being done wrong.

    One really neat concept is embodied in the Perl programming language--tainting. The idea of tainting is that the interpreter tracks the source of data and turns off dangerous operations if they are called directly as a result of user input. For example, when you're running a Perl script in taint mode, it turns on a lot of error checking before passing user-provided data to certain system calls. When you try to open a file for write using a filename that is tainted data, it checks to make sure the directory tree ownerships for the target directory are correct and that the filename doesn't contain "../" path expansions. In other words, the runtime environment tracks not just the type and value of the data but also its origin. You can imagine how nice this capability can be for writing server-side code or captive applications.

    Unfortunately, few programmers use tainting because it imposes an extra burden on the programmer, and it's sometimes difficult to figure out a secure way to get the job done. But what if we built tainting-type capabilities right into our runtime environments for C/C++? A simple high-value approach might be to modify I/O routines (read/write) to determine if they are connected to a socket from a remote system, and to do some basic checks on data coming across it, such as checking to see if the stack is altered across calls to certain functions following I/O.

    Ranum is citing this as an example of a way that existing tools -- such as GCC -- could be enhanced in such a way that programmers using currently popular languages (C/C++) would have a better security safety net without having to be retrained in practices (like checking for buffer overflows) that while obvious are still under-utilized in most software. The whole article is interesting reading, but this remark about Perl's taint mode seems like one of the best concrete examples of a modern protective language feature.


  • This is what I want:

    1) An honest-to-goodness, floor-to-ceiling, cradle-to-grave, first-to-last, night-n-day 64-bit environment, with

    2) Strongly-typed data primitives.

    For the first criteria, if, at any point, you are forced to make contact with a 32-bit environment, then the platform fails the test.

    For instance, if the platform requires you to use either Java or SQL, then it fails.

    SQL fails because it is essentially an ASCII-based language that has almost no sense of primitive data types whatsoeve


    • The java code should have read as follows [I didn't notice that the shift operator had been caught by the /. HTML filter]:
      public class SixtyFourBit
      {
      public static void main (String args[])
      {
      long theLong = 1;
      theLong <<= 32;
      theLong += 1;
      System.out.println("theLong = " + theLong);

      double [] theDoubleArray = new double[theLong];
      }
      }

    • Huh. How odd. C/C++ can do this just fine. (Well, C++ with C99 support makes it easier).

      #include <stdint.h>

      int main() {
      int64_t theLong = 1;
      theLong = 32;
      theLong += 1;

      double *theDoubleArray = new double[theLong]; ...
      delete[] theDoubleArray;
      return 0;
      }

      The ABI guys are still trying to figure out how to map all the double sizes. Right now, sizeof(long double) on my x86 machine gives me 12 bytes 96 bit. There is also talk of making a "long long double" of 16 bytes. Sooner or later

      • Huh. How odd. C/C++ can do this just fine...

        Does "C++" have a tape backup package? [As in Seagate-Veritas Backup Exec? Or CA-Cheyenne ARCserve?]

        Does "C++" have seamless background mirroring to a failsafe mirror server? [Preferably in a peer-to-peer relationship, but Master-Slave will do in a pinch.]

        Does "C++" distribute loads across multiple redundant servers?

        Does "C++" have a querying capability? [I.e. can C++ "query" itself the way a relation database can "query" itself?]

        Does "C++" have data tr

  • by egott ( 81357 )
    Languages without "real" unification feel unexpressive or too low level. Whenever I program in something other than prolog (which is most of the time) I miss it.

    Example: [foo(A,x)|B] = [foo([p,q],x),C,d,e].
    which implies that A = [p,q], B = [C,d,e], and C remains unconstrained.
  • for zope-related crap (when i'm in the slave pit, not doing cool stuff) lambdas whip ass.

    you can stuff functions into session variables - how's that for obtuse!

  • by Pierre ( 6251 )
    4.321**2 instead of pow(4.321,2)

  • I like C-like syntax, but for easy prototyping, automatic arrays and hashes are sooo neat! much nicer than garbage collection IMHO. perl makes them easy, once you get over the $,%,@ line noise

    my main problem with that is (besides perl's ugly syntax) that arrays and hashes are different things. that alone makes me use PHP more often than perl.

    but in PHP I have choose all the time between the array/hash thing and the 'object' thing. I'm sure that internally the objects are managed with hashes, but the sy
  • reflection (Score:3, Interesting)

    by agwis ( 690872 ) on Thursday July 08, 2004 @12:21AM (#9639399)
    I'm surprised I haven't seen this listed yet. In java I use reflection often and at the cost of a little processing overhead, it allows me to add remove fields from a database with very little code change.

    I generally like to use struts in web applications and find I often have to tranfer values from an action form to a java bean and vice versa. Using the org.apache.commons.beanutils package it is incredibly easy to do this, and beanutils uses reflection to do this with.

    My second choice would be good regexp support. IMO, Perl is the best at this and I also like the Java regexp package in 1.4 as well.
  • http://www.oreilly.com/catalog/korn2/index.html

    Everything I learnt from it, and all these useful
    features like

    if [[ $foo != @(From\ )* ]]; then ...

    set -A arrayname -- $(head -1 file)
    let i=0
    while (( i "
    let i+=1
    done

    and more stuff like that.

    If you want to update your system to have this
    kind of powerful shell too, read
    http://wiki.mirbsd.de/MirbsdKsh
    and, for prompt lovers who don't like the
    simplistic '$ ' PS1,
    https://mirbsd.bsdadvocacy.org:8890/cvs.cgi / src/et c/profile

    gl hf
    • Oups, mangled.

      Should have been

      while (( i < ${#arrayname[*]} )); do
      print "$i = <${arrayname[i]}>"
      let i+=1

      I've just seen GNU bash has "shopt -s extglob",
      but not the (supposedly more portable than
      echo) print builtin... gah.

      Also, check out coroutines in the ksh book
      or manpage, they're REALLY powerful.
  • My personal favourite is the while-loop. With the while loop I can construct for-loops, do-while-loops and even if and if-else constructs.

    Only slightly ;-)

  • by Simon ( 815 ) <simon@[ ]onzone.com ['sim' in gap]> on Thursday July 08, 2004 @01:44AM (#9639719) Homepage
    #1 Garbage collection. a.k.a. automatic memory management. Not very sexy, but by far the single biggest productivity boosting feature of any language. I hate housework. It is just a waste of time.

    #2 No pointers, no buffer overruns, no memory corruption. Related to the first point. Memory corruption is just so hard track down. You can keep your pointers, I've already got an OS, I don't need to write my own. :)

    After spending years programing asm and C on a platform with no memory protection (Amiga), and then later C++, I think I've paid my dues here.

    #3 Stack traces. Not a language feature per se, but it takes a lot of the drudge work out of debugging.

    #4 Python's 'for' loop for iterating over the contents of a list or array:

    for thing in myarray:
    mutate(thing)

    It is easy to remember, easy to type, much easier to read, and you use it _all_ the time. Compared to the same code in C, C++ or Java, it is a godsend.

    #5 Dictionaries, a.k.a. associative arrays. It just makes a lot of problems much much simplier and faster to solve. Sure, most other languages have dictionaries available as a class, but when they are seamlessly built into the language you use them as easily as any other primitive datatype.

    --
    Simon
    • Don't bash C++ (Score:5, Informative)

      by Chemisor ( 97276 ) on Thursday July 08, 2004 @08:36AM (#9641414)
      > #1 Garbage collection. a.k.a. automatic memory
      > management. Not very sexy, but by far the single
      > biggest productivity boosting feature of any
      > language. I hate housework. It is just a waste of time.

      Garbage collection does not free you from memory management. It simply converts one kind of problem into another: namely it eliminates accesses of unallocated memory, but it creates memory leaks instead. The thing is, it is not always easy to figure out when you no longer need a block of memory. That's with garbage collection it is supposed to be good practice to "free" your pointers anyway, by assigning NULL to them. Why they can't just use STL containers instead, I don't know.

      > #2 No pointers, no buffer overruns, no memory
      > corruption. Related to the first point. Memory
      > corruption is just so hard track down. You can
      > keep your pointers

      You won't have any memory corruption if you don't use arbitrary indexes to access your arrays. For example, when iterating over a container, you run your iterator from ctr.begin() to ctr.end(); no corruption possible. The other cause of memory corruption is using unverified data to directly access your arrays. That happens when you ask the user for a number and then use it to index; this is wrong in so many ways, I can't even begin to list them all. Verify your data, and you will not have any data corruption.

      > #3 Stack traces. Not a language feature per se,
      > but it takes a lot of the drudge work out of
      > debugging.

      #include
      backtrace_symbols()

      > #4 Python's 'for' loop for iterating over the
      > contents of a list or array:
      >
      > for thing in myarray:
      > mutate(thing)

      #define foreach(t,i,c) for(t i = c.begin(); i #5 Dictionaries, a.k.a. associative arrays. It
      > just makes a lot of problems much much simplier
      > and faster to solve.

      map m;

      > Sure, most other languages
      > have dictionaries available as a class, but when
      > they are seamlessly built into the language you
      > use them as easily as any other primitive '
      > datatype.

      You can use map as easily as any other primitive data type of the same category: as an array.
      m["january"] = 31;
      cout "january has " m["january"] " days" endl;
  • For stack-based hardware, FORTH is very powerful. A tiny interpreter (even on chip-level) and screamingly fast. PostScript is similarly stack-based, but its huge base vocabulary is less than ideal for beginning programming.

    In a similar vein, I've been pondering the feasibility of a no-GP-register CPU. Low addresses (say, the first 31 words) are stored on-chip, the rest in slower memory. Data is accessed via two memory-address registers (a la the M reg in the old 8080, which turned into (HL) in the Z80) t
  • I've found TCL's slave interpreter very useful. It allows you to execute "uncontrolled" TCL code securely, trapping/substituting/exposing whatever you want. Variables can be exposed, hidden, readonly, etc.

    In particular, I find it useful when allowing an application written in TCL to be scripted. The TCL application can remain robust and reliable, even when the user code isn't.
  • Forgive me if this is already mentioned, but it's a neat little perl trick that I dreamed up on my own (though I'm probably not the first).

    It's an easy way of developing a command-driven interface (which is useful if you're developing a web-app or even for limited-functionality command shells).

    So for example, the user's command is stored in the variable $cmd. We then have hash %cmds which stores all the possible commands like this:

    $cmds{foobar} = sub { print "this is the foobar command"; };
    $cmds{bazqu

  • by rasjani ( 97395 ) on Thursday July 08, 2004 @06:31AM (#9640555) Homepage
    I dont remember what the syntax actually was but when you defined a structure, you could point into its members with with.

    like if the structure had members x and y and structure was named coords you could do something like this

    var own_x;
    with coords
    begin
    x=own_x
    y=123.13
    end

  • A few favorites (Score:3, Interesting)

    by scruffy ( 29773 ) on Thursday July 08, 2004 @11:53AM (#9643922)
    Garbage collection

    Unrestricted integer size (e.g., Lisp bignums)

    Have persistent objects between program invocations. It's so tedious and buggy to have to write to a file when a program ends and then read it again when you start it up again.

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