Search Results

Search found 78 results on 4 pages for 'interpreters'.

Page 3/4 | < Previous Page | 1 2 3 4  | Next Page >

  • How to implement arrays in an interpreter?

    - by Ray
    I have managed to write several interpreters including Tokenizing Parsing, including more complicated expressions such as ((x+y)*z)/2 Building bytecode from syntax trees Actual bytecode execution What I didn't manage: Implementation of dictionaries/lists/arrays. I always got stuck with getting multiple values into one variable. My value structure (used for all values passed around, including variables) looks like this, for example: class Value { public: ValueType type; int integerValue; string stringValue; } Works fine with integers and strings, but how could I implement arrays? (From now on with array I mean arrays in my experimental language, not in C++) How can I fit the array concept into the Value class above? Is it possible? How should I make arrays able to be passed around just as you could pass around integers and strings in my language, using the class above? Accessing array elements or memory allocation wouldn't be the problem, I just don't know how to store them.

    Read the article

  • How does an interpreter switch scope?

    - by Dox
    I'm asking this because I'm relatively new to interpreter development and I wanted to know some basic concepts before reinventing the wheel. I thought of the values of all variables stored in an array which makes the current scope, upon entering a function the array is swapped and the original array put on some sort of stack. When leaving the function the top element of the "scope stack" is popped of and used again. Is this basically right? Isn't swapping arrays (which means moving around a lot of data) not very slow and therefore not used by modern interpreters?

    Read the article

  • Dependency issue in inheritance chain

    - by Razer
    I have a class in coffeescript a class layout like the following. class @A foo: -> console.log('foo') class @B extends A fooB: -> @foo() class @C extends B fooC: -> @foo() I tried this in interpreters, it works. However it raises errors, when executing this in the browser (all of them are in separate coffee files, and are used in a global context. Therefore the @ before the class): Uncaught ReferenceError: B is not defined application.js It seems that B is defined after the definition of C. How can this happen?

    Read the article

  • New or not so well-known paradigms, syntax features and behaviours of programming languages?

    - by George B
    I've designed some educational programming languages and interpreters for them, but my problem always was that they ended up "normal" and "boring", mostly similar to some kind of existing language (ASM and BASIC). I find it really hard to come up with new ideas for syntax features, "neat things" and new or very modified programming paradigms for it. I always thought that it was hard to come up with good new things not fun/useless new things for this case. I wondered if you could help me out with your creativity: What features in terms of language syntax and built-in functions as well as maybe even new paradigms can I work into my language to keep it useless but more fun, enjoyable, interesting and/or different to program in?

    Read the article

  • Scheme open source projects?

    - by Ben
    Hi I'm learning scheme and was wondering if there are any active open-source projects I might be able to get involved in? I'm nearing the end of SICP and although this has good complex examples no textbook code compares to real-world applications. eg testing code / benchmarking / revision control styles / sheer size and scope etc. Hence my curiousity at seeing a project in the wild. I tried searching google code but only found projects that are interpreters that implement RSR5/6. Perhaps there are not many projects out there and I should consider scala?! Advice or even pointers to specific projects appreciated.

    Read the article

  • C++ Interpreter: How to emit error messages?

    - by Rawr
    I want to emit dynamic error messages like all interpreters do nowadays, for example: Name error: Undefined variable would be constant, however what I want to reach is: Name error: Undefined variable 'X', in line 1 Okay. The line number was really no problem: Every error message must have a line number, so I added it to the error emitter function: Error( ErrType type, string msg, int line ); So where is my problem? How do I get the 'X' into Undefined variable *? I can't use sprintf as it doesn't support strings yet I use them everywhere I can't simply use cout and connect everything as I want error messages to be supressable I'd like to get everything into one function like above, Error() How do I put together dynamic error messages? For example: Error( Name, sprintf("Undefined variable %s", myVariableName ), lineNum ); (But myVariableName is a string and sprintf will mess things up)

    Read the article

  • Debugging PHP in Aptana 2.0

    - by Nick Lowman
    I'm a real newbie when it comes to PHP debugging so forgive my stupidity. I have a simple html form that submits to a PHP script and I want to debug that script and see what's being sent from the form. My Aptana has two two PHP interpreters installed; Zend Debugger on port 10001 and XDebug on 9000 I have the Firefox Aptana Addon installed I have my HTML page on the following url, running locally; http://3i/latest.html In the IDE I open the PHP script and add some breakpoints, I then open the latest.html and I click on the debug button. It launches the HTML page in a local webserver running at; http://127.0.0.1:8000/3i/latest.html I then fill out the form and submit at which point the debugger tells me the JS Debugger has terminated but it doesn't stop at my break points. I've had a good read around and I can't find anything which helps me, which makes me think it's something pretty easy and I'm being a bit dumb.

    Read the article

  • Is there a way to include commas in CSV columns without breaking the formatting?

    - by editor
    I've got a two column CSV with a name and a number. Some people's name use commas, for example "Joe Blow, CFA." This comma breaks the CSV format, since it's interpreted as a new column. I've read up and the most common prescription seems to be replacing that character, or replacing the delimiter, with a new value (e.g. "this|that|the, other"). I'd really like to keep the comma separator (I know excel supports other delimiters but other interpreters may not). I'd also like to keep the comma in the name, as "Joe Blow| CFA" looks pretty silly. Is there a way to include commas in CSV columns without breaking the formatting, for example by escaping them?

    Read the article

  • How do I learn Scheme?

    - by Gautam
    Hey, I'm a relative newbie to programming. I've picked up some very basic Java (File I/O, GUIs, inheritance) and would like to take a look at functional programming - in particular, I would like to learn Scheme. I'm having some trouble finding a Scheme implementation I can understand. Interpreters are weird; I'm not sure how to save my programs and create executables. I've downloaded PLT Scheme, but I would prefer using something less condescending, something similar to NetBeans. Is there a plugin or tool that will allow me to quickly and easily create and manage Scheme programs? All help is appreciated!

    Read the article

  • Will Haskell be a good choice for my task?

    - by Narzanka
    I'm starting a new project and don't know which language to use. My 'must have' requirements are: Be able to run on Windows/LinuxMacOs natively (native executable) - user should be able to just run the exe (when on Windows for example) and see the results. No runtimes/interpreters (no jvm, clr, etc) - one file download should be enough to run the application. Full unicode support. Be able to manipulate OS threads (create them, run multiple tasks in parallel on multi-core CPUs, etc). Be reasonably fast (Python level performance and better). To have some kind of standard library that does low-level, mundane tasks. Not very niche and have some community behind it to be able to ask questions. My 'nice to have' requirements are: Language should be functional It should have good string manipulation capabilities (not necessarily regex) Not extremely hard to learn I'm thinking about Haskell now but keeping in mind OCaml as well. Please advice if my choice is correct.

    Read the article

  • Creating a bare bone web-browser: After the html parser, javascript parser, etc have done their work, how do I display the content of the webpage?

    - by aste123
    This is a personal project to learn computer programming. I took a look at this: https://www.udacity.com/course/viewer#!/c-cs262 The following is the approach taken in it: Abstract Syntax Tree is created. But javascript is still not completely broken down in order not to confuse with the html tags. Then the javascript interpreter is called on it. Javascript interpreter stores the text from the write() and document.write() to be used later. Then a graphics library in Python is called which will convert everything to a pdf file and then we convert it into png or jpeg and then display it. My Question: I want to display the actual text in a window (which I will design later) like firefox or chrome does instead of image files so that the data can be selected, copied, etc by the user of the browser. How do I accomplish this? In other words, what are the other elements of a bare bone web browser that I am missing? I would prefer to implement most of the stuff in C++ although if things seem too complicated I might go with Python to save time and create a prototype and later creating another bare bone browser in C++ and add more features. This is a project to learn more. I do realize we already have lots of reliable browsers like firefox, etc. The way I feel it is done: I think after all the broken down contents have been created by the parsers and interpreters, I will need to access them individually from within the window's code (like qt) and then decide upon a good way to display them. I am not sure if it is the way this should be done. Additions after useful comment by Kilian Foth: I found this page: http://friendlybit.com/css/rendering-a-web-page-step-by-step/ 14. A DOM tree is built out of the broken HTML 15. New requests are made to the server for each new resource that is found in the HTML source (typically images, style sheets, and JavaScript files). Go back to step 3 and repeat for each resource. 16. Stylesheets are parsed, and the rendering information in each gets attached to the matching node in the DOM tree 17. Javascript is parsed and executed, and DOM nodes are moved and style information is updated accordingly 18. The browser renders the page on the screen according to the DOM tree and the style information for each node 19. You see the page on the screen I need help with step 18. How do I do that? How much work do Webkit and Gecko do? I want to use a readymade layout renderer for step number 18 and not for anything that comes before that.

    Read the article

  • Low level programming - what's in it for me?

    - by back2dos
    For years I have considered digging into what I consider "low level" languages. For me this means C and assembly. However I had no time for this yet, nor has it EVER been neccessary. Now because I don't see any neccessity arising, I feel like I should either just schedule some point in time when I will study the subject or drop the plan forever. My Position For the past 4 years I have focused on "web technologies", which may change, and I am an application developer, which is unlikely to change. In application development, I think usability is the most important thing. You write applications to be "consumed" by users. The more usable those applications are, the more value you have produced. In order to achieve good usability, I believe the following things are viable Good design: Well-thought-out features accessible through a well-thought-out user interface. Correctness: The best design isn't worth anything, if not implemented correctly. Flexibility: An application A should constantly evolve, so that its users need not switch to a different application B, that has new features, that A could implement. Applications addressing the same problem should not differ in features but in philosophy. Performance: Performance contributes to a good user experience. An application is ideally always responsive and performs its tasks reasonably fast (based on their frequency). The value of performance optimization beyond the point where it is noticeable by the user is questionable. I think low level programming is not going to help me with that, except for performance. But writing a whole app in a low level language for the sake of performance is premature optimization to me. My Question What could low level programming teach me, what other languages wouldn't teach me? Am I missing something, or is it just a skill, that is of very little use for application development? Please understand, that I am not questioning the value of C and assembly. It's just that in my everyday life, I am quite happy that all the intricacies of that world are abstracted away and managed for me (mostly by layers written in C/C++ and assembly themselves). I just don't see any concepts, that could be new to me, only details I would have to stuff my head with. So what's in it for me? My Conclusion Thanks to everyone for their answers. I must say, nobody really surprised me, but at least now I am quite sure I will drop this area of interest until any need for it arises. To my understanding, writing assembly these days for processors as they are in use in today's CPUs is not only unneccesarily complicated, but risks to result in poorer runtime performance than a C counterpart. Optimizing by hand is nearly impossible due to OOE, while you do not get all kinds of optimizations a compiler can do automatically. Also, the code is either portable, because it uses a small subset of available commands, or it is optimized, but then it probably works on one architecture only. Writing C is not nearly as neccessary anymore, as it was in the past. If I were to write an application in C, I would just as much use tested and established libraries and frameworks, that would spare me implementing string copy routines, sorting algorithms and other kind of stuff serving as exercise at university. My own code would execute faster at the cost of type safety. I am neither keen on reeinventing the wheel in the course of normal app development, nor trying to debug by looking at core dumps :D I am currently experimenting with languages and interpreters, so if there is anything I would like to publish, I suppose I'd port a working concept to C, although C++ might just as well do the trick. Again, thanks to everyone for your answers and your insight.

    Read the article

  • What are the reasons to use dos batch programs in Windows?

    - by DVK
    Question What would be a good (ideally, technical) reason to ever program some non-trivial task in dos batch language on a modern Windows system as opposed to downloading either PowerShell, or ActiveState Perl? To be more specific, I make the following two assumptions for the duration of this question: anyone technical enough to be able to write a medium-complexity batch script is technical enough to install either of the scripting interpreters. Neither of those two present enough of a learning curve for basic batch replacement tasks that said curve would outweigh the pain of doing any remotely-non-trivial task in batch. Notes "You need a batch program for autoexec.bat" is not a valid reason. Your autoexec.bat may consist of simply calling non-batch script. If you disagree with either of my 2 assumptions above, that's fine, and I may be wrong. But my question is specifically "assuming those 2 assumptions are correct, what would be the reason to still stick with batch?" If it makes it easier to suspend disbelief (in case you disagree with me), add in a 3rd assumption that the question is limited to people who already posess at least some modicum of PowerShell or Perl experience. To re-iterate - this is not meant to be a subjective question about how easy it is to learn PSh or ASPerl compared to doing advanced batch coding. That is a separate question that is too subjective to be bothered with in this post. Background: I used to do some fairly complicated batch programming back in the elder days, and remember batch as one of the worst possble programming languages I had encountered. The idea for this question came after seeing a bunch of batch questions on SO, and trying to grok the answer of one of them out of sheer curiosity and giving up in pain after a minute, exclaiming mentally "why would anyone go through this pain instead of doing that in 1 line of Perl?" :) My own plausible answer I assume there may be an an likely DOS-compatible system, which has DOS interpreter but has no compatible PowerShell or Perl... I'm not aware of one but not completely impossible.

    Read the article

  • Python - Help with multiprocessing / threading basics.

    - by orokusaki
    I haven't ever used multi-threading, and I decided to learn it today. I was reluctant to ever use it before, but when I tried it out it seemed way to easy, which makes me wary. Are there any gotchas in my code, or is it really that simple? import uuid import time import multiprocessing def sleep_then_write(content): time.sleep(5) f = open(unicode(uuid.uuid4()), 'w') f.write(content) f.close() if __name__ == '__main__': for i in range(3): p = multiprocessing.Process(target=sleep_then_write, args=('Hello World',)) p.start() My primary purpose of using threading would be to offload multiple images to S3 after re-sizing them, all at the same time. Is that a reasonable task for Python's multiprocessing? I've read a lot about certain types of tasks not really getting any gain from using threading in Python due to the GIL, but it seems that multiprocessing completely removes that worry, yes? I can imagine a case where 50 users hit the system and it spawns 150 Python interpreters. I can also imagine that wouldn't be good on a production server. How can something like that be avoided? Finally (but most important): How can I return control back to the caller of the new processes? I need to be able to continue with returning an HTTP response and content back to the user and then have the processes continue doing there work after the user of my website is done with the transaction.

    Read the article

  • using ghostscript in server mode to convert pdfs to pngs

    - by emh
    while i am able to convert a specific page of a PDF to a PNG like so: gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dGraphicsAlphaBits=4 -sOutputFile=gymnastics-20.png -dFirstPage=20 -dLastPage=20 gymnastics.pdf i am wondering if i can somehow use ghostscript's JOBSERVER mode to process several conversions without having to incur the cost of starting up ghostscript each time. from: http://pages.cs.wisc.edu/~ghost/doc/svn/Use.htm -dJOBSERVER Define \004 (^D) to start a new encapsulated job used for compatibility with Adobe PS Interpreters that ordinarily run under a job server. The -dNOOUTERSAVE switch is ignored if -dJOBSERVER is specified since job servers always execute the input PostScript under a save level, although the exitserver operator can be used to escape from the encapsulated job and execute as if the -dNOOUTERSAVE was specified. This also requires that the input be from stdin, otherwise an error will result (Error: /invalidrestore in --restore--). Example usage is: gs ... -dJOBSERVER - < inputfile.ps -or- cat inputfile.ps | gs ... -dJOBSERVER - Note: The ^D does not result in an end-of-file action on stdin as it may on some PostScript printers that rely on TBCP (Tagged Binary Communication Protocol) to cause an out-of-band ^D to signal EOF in a stream input data. This means that direct file actions on stdin such as flushfile and closefile will affect processing of data beyond the ^D in the stream. the idea is to run ghostscript in-process. the script would receive a request for a particular page of a pdf and would use ghostscript to generate the specified image. i'd rather not start up a new ghostscript process every time.

    Read the article

  • Missing ideas in programming language design

    - by meyka
    I wanted to try something new and so I designed some programming languages and wrote interpreters for them: A rather low-level, not very expressive language. (I didn't want to parse complex expressions right at the beginning) It featured: Variables (yay) Subroutines, with a call stack Basic arithmetic functions, basic string manipulation, ... Code in the language looks like this: set i 0 inc i print i Very, very basic you see. A more high-level language I decided to make it structured and so it featured things like if-else, while, functions, and so on. The stuff most programming languages have. Ended up like a unworthy Python clone, I hated that. A code-golf language Which ended up similar to J, golfcode, APL, etc. Nothing special As you can see: I don't lack the skills but the ideas. I can't figure out anything new, not even bad, unneccessary things, for my languages. - Do you know of some weird things I could implement in my languages, which don't try to make programming harder (like most esoteric languages) but funnier or more different from other languages? It can't be possible that every weird thing has been tried out so far, or?

    Read the article

  • Graphviz or Dynagraph for Graph-manipulation Program?

    - by noahlavine
    I'm looking into writing a program that will show a graph to the user. The graph will change over time (the user should be able to right-click on a graph item and ask for more detail, which will pop out new bits of the graph), and the user might be able to drag parts of the graph around. I would ideally also like to be able to specify the relative layout of certain parts of the graph myself while leaving the overall layout up to a library, but that's not essential. I'm trying to decide on a graph layout library to use. As far as I can tell, the two leading candidates are Graphviz and Dynagraph. The Dynagraph website suggests that Graphviz is for drawing static graphs, and that Dynagraph was forked from Graphviz and contains algorithms for graphs that will be updated. It has a sample program called Dynasty that does exactly what I want. However, the Graphviz site contains an example program called Lefty which seems to do exactly what I want. Graphviz also seems to be much more widely used, judging by Google (and SO) results. Finally, I'd like to code the GUI part in a language like Python or Scheme, which makes me a bit hesitant to use C++ because I understand it's harder to interface that to interpreters. So my question is, which library is better for what I'm trying to do? Do they both have strong and weak points? Has one of them actually ceased development and is just leaving its website up to confuse me? (I've seen http://stackoverflow.com/questions/464000/simple-dynamic-graph-display-for-c and http://stackoverflow.com/questions/2376987/open-source-libraries-to-design-directed-graphs, but I can't tell whether they're right about the Graphviz or Dynagraph choice because of Lefty and also the language issue.)

    Read the article

  • ASP.NET MVC Using Castle Windsor IoC

    - by Mad Halfling
    I have an app, modelled on the one from Apress Pro ASP.NET MVC that uses castle windsor's IoC to instantiate the controllers with their respective repositories, and this is working fine e.g. public class ItemController : Controller { private IItemsRepository itemsRepository; public ItemController(IItemsRepository windsorItemsRepository) { this.itemsRepository = windsorItemsRepository; } with using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using Castle.Windsor; using Castle.Windsor.Configuration.Interpreters; using Castle.Core.Resource; using System.Reflection; using Castle.Core; namespace WebUI { public class WindsorControllerFactory : DefaultControllerFactory { WindsorContainer container; // The constructor: // 1. Sets up a new IoC container // 2. Registers all components specified in web.config // 3. Registers all controller types as components public WindsorControllerFactory() { // Instantiate a container, taking configuration from web.config container = new WindsorContainer(new XmlInterpreter(new ConfigResource("castle"))); // Also register all the controller types as transient var controllerTypes = from t in Assembly.GetExecutingAssembly().GetTypes() where typeof(IController).IsAssignableFrom(t) select t; foreach (Type t in controllerTypes) container.AddComponentWithLifestyle(t.FullName, t, LifestyleType.Transient); } // Constructs the controller instance needed to service each request protected override IController GetControllerInstance(Type controllerType) { return (IController)container.Resolve(controllerType); } } } controlling the controller creation. I sometimes need to create other repository instances within controllers, to pick up data from other places, can I do this using the CW IoC, if so then how? I have been playing around with the creation of new controller classes, as they should auto-register with my existing code (if I can get this working, I can register them properly later) but when I try to instantiate them there is an obvious objection as I can't supply a repos class for the constructor (I was pretty sure that was the wrong way to go about it anyway). Any help (especially examples) would be much appreciated. Cheers MH

    Read the article

  • Getting my foot in the SCADA door, how?

    - by bibby
    I keep hearing that I should learn SCADA and its PLC language to upgrade my career. While I enjoy currently being a web and mobile development privateer, the prospects of working for a municipality or industrial entity has its appeals (since I am trying to grow a family). Over the years, I've tought myself to skillfully use php, javascript, java, perl, awk, bash. Surely, these language skills can tranfer somewhat to SCADA's logic controller language. Without any formal training in CS (music major!) other than at the workplace, I wouldn't have been able to pick up those languages and run with them had it not been for their open documentation and free-to-install or already-installed interpreters/compilers. I can't see that this is true with SCADA, and I'm hoping that I'm wrong. Ideally, I'd like to be able to apply for a job that requires [A,B,C] and suggest that they hire me because I already know [A & B]; that they wouldn't have to do a ground-up training with someone that's never programmed before. So, finally, the question; How do I "learn" SCADA? Are there sites and docs? What's going to help me get my foot in the door? Any insight is appreciated. Thanks!

    Read the article

  • C++ interpreter conceptual problem

    - by Jan Wilkins
    I've built an interpreter in C++ for a language created by me. One main problem in the design was that I had two different types in the language: number and string. So I have to pass around a struct like: class myInterpreterValue { myInterpreterType type; int intValue; string strValue; } Objects of this class are passed around million times a second during e.g.: a countdown loop in my language. Profiling pointed out: 85% of the performance is eaten by the allocation function of the string template. This is pretty clear to me: My interpreter has bad design and doesn't use pointers enough. Yet, I don't have an option: I can't use pointers in most cases as I just have to make copies. How to do something against this? Is a class like this a better idea? vector<string> strTable; vector<int> intTable; class myInterpreterValue { myInterpreterType type; int locationInTable; } So the class only knows what type it represents and the position in the table This however again has disadvantages: I'd have to add temporary values to the string/int vector table and then remove them again, this would eat a lot of performance again. Help, how do interpreters of languages like Python or Ruby do that? They somehow need a struct that represents a value in the language like something that can either be int or string.

    Read the article

  • How do I get started designing and implementing a script interface for my .NET application?

    - by Peter Mortensen
    How do I get started designing and implementing a script interface for my .NET application? There is VSTA (the .NET equivalent of VBA for COM), but as far as I understand I would have to pay a license fee for every installation of my application. It is an open source application so this will not work. There is also e.g. the embedding of interpreters (IronPython?), but I don't understand how this would allow exposing an "object model" (see below) to external (or internal) scripts. What is the scripting interface story in .NET? Is it somehow trivial in .NET to do this? Background: I have once designed and implemented a fairly involved script interface for a Macintosh application for acquisition and analysis of data from a mass spectrometer (Mac OS, System 7) and later a COM interface for a Windows application. Both were designed with an "object model" and classes (that can have properties). These are overloaded words, but in a scripting interface context object model is essentially a containment hiarchy of objects of specific classes. Classes have properties and lists of contained objects. E.g. like in the COM interfaces exposed in Microsoft Office applications, where the application object can be used to add to its list of documents (with the side effect of creating the GUI representation of a document). External scripts can create new objects in a container and navigate through the content of the hiarchy at any given time. In the Macintosh case scripts could be written in e.g. AppleScript or Frontier. On the Macintosh the implementation of a scripting interface was very complicated. Support for it in Metroworks' C++ class library (the name escapes me right now) made it much simpler.

    Read the article

  • What is the current status of LOGO? (The programming language)

    - by Workshop Alex
    In another Q I saw someone mention LOGO and it reminded me of some programming language from the past, mostly used for educational purposes. Basically, you would have to program a turtle with a pen through it's back. By telling it where to move, the pen would draw lines. It could also lift the pen to move without drawing lines. I have fond memories of this language, since it was one of the first I've ever used, about 30 years ago. (Yeah, I'm old.) Well, I only programmed with LOGO for two days or so, but it got me hooked to programming. But I wonder if the LOGO information on it's Wikipedia page is still correct. And more importantly, are there versions that will create .NET binaries? Are there only LOGO Interpreters and no compilers? What is the current status of this educational language? And more interestingly, are there more experts here at SO who have experimented with LOGO in the past? Yeah, I know. Nowadays this language is a bit antique but I got some warm and comfortable memories when I remembered this interesting language from my history. For a teenager back then, it was fun!

    Read the article

  • java: libraries for immutable functional-style data structures

    - by Jason S
    This is very similar to another question (Functional Data Structures in Java) but the answers there are not particularly useful. I need to use immutable versions of the standard Java collections (e.g. HashMap / TreeMap / ArrayList / LinkedList / HashSet / TreeSet). By "immutable" I mean immutable in the functional sense (e.g. purely functional data structures), where updating operations on the data structure do not change the original data, but instead return a new instance of the same kind of data structure. Also typically new and old instances of the data structure will share immutable data to be efficient in time and space. From what I can tell my options include: Functional Java Scala Clojure but I'm not sure whether any of these are particularly appealing to me. I have a few requirements/desirements: the collections in question should be usable directly in Java (with the appropriate libraries in the classpath). FJ would work for me; I'm not sure if I can use Scala's or Clojure's data structures in Java w/o having to use the compilers/interpreters from those languages and w/o having to write Scala or Clojure code. Core operations on lists/maps/sets should be possible w/o having to create function objects with confusing syntaxes (FJ looks slightly iffy) They should be efficient in time and space. I'm looking for a library which ideally has done some performance testing. FJ's TreeMap is based on a red-black tree, not sure how that rates. Documentation / tutorials should be good enough so someone can get started quickly using the data structures. FJ fails on that front. Any suggestions?

    Read the article

  • C++ and its type system: How to deal with data with multiple types?

    - by sub
    "Introduction" I'm relatively new to C++. I went through all the basic stuff and managed to build 2-3 simple interpreters for my programming languages. The first thing that gave and still gives me a headache: Implementing the type system of my language in C++ Think of that: Ruby, Python, PHP and Co. have a lot of built-in types which obviously are implemented in C. So what I first tried was to make it possible to give a value in my language three possible types: Int, String and Nil. I came up with this: enum ValueType { Int, String, Nil }; class Value { public: ValueType type; int intVal; string stringVal; }; Yeah, wow, I know. It was extremely slow to pass this class around as the string allocator had to be called all the time. Next time I've tried something similar to this: enum ValueType { Int, String, Nil }; extern string stringTable[255]; class Value { public: ValueType type; int index; }; I would store all strings in stringTable and write their position to index. If the type of Value was Int, I just stored the integer in index, it wouldn't make sense at all using an int index to access another int, or? Anyways, the above gave me a headache too. After some time, accessing the string from the table here, referencing it there and copying it over there grew over my head - I lost control. I had to put the interpreter draft down. Now: Okay, so C and C++ are statically typed. How do the main implementations of the languages mentioned above handle the different types in their programs (fixnums, bignums, nums, strings, arrays, resources,...)? What should I do to get maximum speed with many different available types? How do the solutions compare to my simplified versions above?

    Read the article

  • Can't get MySQL to install

    - by James Marthenal
    I'd like to think I know what I'm doing in a Unix shell but maybe not. I made a mistake in a configuration file for MySQL, so I decided to just uninstall it and then reinstall it, so I did: sudo apt-get --purge remove mysql-server mysql-server-5.0 mysql-client The files were deleted, so I then tried to install it, but it didn't ask me for a root password or anything else, so I uninstalled it using the above command again and then did sudo rm -rf /etc/mysql sudo rm /etc/init.d/mysql sudo rm -rf /var/lib/mysql* I then restarted the computer then installed it again: sudo apt-get install mysql-server mysql-client It asked for a root password, and everything looked like it would work, until I saw this: $ sudo apt-get install mysql-server mysql-client Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: mysql-server-5.0 Suggested packages: tinyca The following NEW packages will be installed: mysql-client mysql-server mysql-server-5.0 0 upgraded, 3 newly installed, 0 to remove and 1 not upgraded. Need to get 0B/27.4MB of archives. After this operation, 86.7MB of additional disk space will be used. Do you want to continue [Y/n]? y WARNING: The following packages cannot be authenticated! mysql-server-5.0 mysql-client mysql-server Authentication warning overridden. Preconfiguring packages ... Can't exec "/tmp/mysql-server-5.0.config.28101": Permission denied at /usr/share/perl/5.10/IPC/Open3.pm line 168. open2: exec of /tmp/mysql-server-5.0.config.28101 configure failed at /usr/share/perl5/Debconf/ConfModule.pm line 59 mysql-server-5.0 failed to preconfigure, with exit status 255 Selecting previously deselected package mysql-server-5.0. (Reading database ... 160284 files and directories currently installed.) Unpacking mysql-server-5.0 (from .../mysql-server-5.0_5.0.51a-24+lenny5_amd64.deb) ... Selecting previously deselected package mysql-client. Unpacking mysql-client (from .../mysql-client_5.0.51a-24+lenny5_all.deb) ... Selecting previously deselected package mysql-server. Unpacking mysql-server (from .../mysql-server_5.0.51a-24+lenny5_all.deb) ... Processing triggers for man-db ... Setting up mysql-server-5.0 (5.0.51a-24+lenny5) ... Stopping MySQL database server: mysqld. /var/lib/dpkg/info/mysql-server-5.0.postinst: line 144: /etc/mysql/conf.d/old_passwords.cnf: No such file or directory dpkg: error processing mysql-server-5.0 (--configure): subprocess post-installation script returned error exit status 1 Setting up mysql-client (5.0.51a-24+lenny5) ... dpkg: dependency problems prevent configuration of mysql-server: mysql-server depends on mysql-server-5.0; however: Package mysql-server-5.0 is not configured yet. dpkg: error processing mysql-server (--configure): dependency problems - leaving unconfigured Errors were encountered while processing: mysql-server-5.0 mysql-server E: Sub-process /usr/bin/dpkg returned an error code (1) Now I can't seem to figure out what to do. I just want to get a clean MySQL installation at this point. I'm running the latest stable release of Debian. All help is appreciated—thanks! Edit: I looked at this similar question, which suggests that I uninstall mysql-common, but when I try to do so I see: The following packages will be REMOVED: apache2 apache2-mpm-prefork apache2-utils apache2.2-common git-svn libapache2-mod-php5 libapache2-mod-python libapache2-svn libaprutil1 libdbd-mysql-perl libdbd-mysql-rubygem libmysql-ruby libmysql-ruby1.8 libmysql-rubygem libmysqlclient15-dev libmysqlclient15off librdf-perl librdf0 libserf-0-0 libsvn-perl libsvn1 mysql-client-5.0 mysql-common mytop ndn-apache22-php5 ndn-apache22-svn ndn-interpreters ndn-lighttpd ndn-netsaint-plugins ndn-perl-modules ndn-php5-cgi ndn-php5-xcache ndn-php53 ndn-php53-suhosin ndn-rubygems php5 php5-mcrypt php5-mysql proftpd proftpd-mod-mysql python-django python-mysqldb python-subversion python-svn subversion subversion-tools trac zendoptimizer 0 upgraded, 0 newly installed, 48 to remove and 1 not upgraded. Eeek! Any suggestions?

    Read the article

< Previous Page | 1 2 3 4  | Next Page >