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  • Why is Python slower than Java but faster than PHP

    - by good_computer
    I have many times seen various benchmarks that show how a bunch of languages perform on a given task. Always these benchmarks reveal that Python is slower then Java and faster than PHP. And I wonder why is that the case. Java, Python, and PHP run inside a virtual machine All three languages convert their programs into their custom byte codes that run on top of OS -- so none is running natively Both Java and Python can be "complied" (.pyc for Python) but the __main__ module for Python is not compiled Python and PHP are dynamically typed and Java statically -- is this the reason Java is faster, and if so, please explain how that affects speed. And, even if the dynamic-vs-static argument is correct, this does not explain why PHP is slower than Python -- because both are dynamic languages. You can see some benchmarks here and here, and here

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  • When Programming will become deprecated [closed]

    - by Vibeeshan
    Possible Duplicate: Will programmers be around in a few years? According to the history of programming, with each new generation of software engineering it seems to become easier and easier. Machine Code - Assembly - Programming Languages - easier - more easier - etc. If this situation continues anyone will be able to program (even complex systems). Even now, most of the kids study programming at school (Pascal , VB, etc.). Will be there any jobs called software engineering in future (if everyone know to program). ....and.... What do you think about the future of software development?

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  • Can aptitude for learning Programming paradigms be influenced by culture or native language's gramma

    - by DVK
    It is well known that different people have different aptitudes regarding various programming paradigms (e.g. some people have trouble learning non-procedural, especially functional languages. Some people have trouble understanding pointers - see Joel Spolsky's blog for musings on that. Some people have trouble grasping recursion). I was recently reading about a study that looked at how the grammar of someone's native language affected their speed of learning math. Can't find that article now but a quick googling found this reference. That led me to wondering whether someone's native culture or first language might affect their aptitude towards various programming paradigms. I'm more curious about positive influences - e.g. some trait that make it easier/faster for someone to learn a particular paradigm, for example native language grammar being very recursion-oriented. To be clear, I'm looking for how culture/language grammare may affect the difference between aptitude of the same person towards various paradigms as opposed to how it affects overall aptitude towards programming between different persons. Important: the only answers I'm interested in are either references to scientific studies, or personal observations from someone intimately familiar with a particular culture/language, including from their own experience. E.g. I'm not interested in your opinion of how Chinese being your first language affects anything unless you speak Chinese or worked with extremely large set of Chinese-native programmers extensively. I'm OK with your guesstimates not based on scientific studies, but please be sure to supply your reasoning about plausible causes of your observation. I'm not interested in culture-bashing (any such commends will be deleted or flagged for deletion). I'm also not particularly interested in culture-building - we all know Linus is from Finland and Tetris was written in Russia and Larry Wall is an American. Any culture/nation can produce a brilliant mind in any discipline. I'm interested in averages.

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  • Coding a parser for a domain specific language in Java

    - by Bruno Rothgiesser
    We want to design a simple domain specific language for writing test scripts to automatically test a XML-based interface of one of our applications. A sample test would be: Get an input XML file from network shared folder or subversion repository Import the XML file using the interface Check if the import result message was successfull Export the XML corresponding to the object that was just imported using the interface and check if it correct. If the domain specific language can be declarative and its statements look as close as my sentences in the sample above as possible, it will be awesome because people won't necessarily have to be programmers to understand/write/maintain the tests. Something like: newObject = GET FILE "http://svn/repos/template1.xml" reponseMessage = IMPORT newObject newObjectID = GET PROPERTY '/object/id/' FROM responseMessage (..) But then I'm not sure how to implement a simple parser for that languange in Java. Back in school, 10 years ago, I coded a language parser using Lex and Yacc for the C language. Maybe an approach would be to use some equivalent for Java? Or, I could give up the idea of having a declarative language and choose an XML-based language instead, which would possibly be easier to create a parser for? What approach would you recommend?

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  • Moses v1.0 multi language ini file

    - by Milan Kocic
    I was working with mosesserver 0.91 and everything works fine but now there is version 1.0 and nothing is same as before. Here is my situation: I want to have multi language translation from arabic to english and from english to arabic. All data and configuration file I have works with 0.91 version of mosesserver. Here is my config file: ------------------------------------------------- ######################### ### MOSES CONFIG FILE ### ######################### # D - decoding path, R - reordering model, L - language model [translation-systems] ar-en D 0 R 0 L 0 en-ar D 1 R 1 L 1 # input factors [input-factors] 0 # mapping steps [mapping] 0 T 0 1 T 1 # translation tables: table type (hierarchical(0), textual (0), binary (1)), source-factors, target-factors, number of scores, file # OLD FORMAT is still handled for back-compatibility # OLD FORMAT translation tables: source-factors, target-factors, number of scores, file # OLD FORMAT a binary table type (1) is assumed [ttable-file] 1 0 0 5 /mnt/models/ar-en/phrase-table/phrase-table 1 0 0 5 /mnt/models/en-ar/phrase-table/phrase-table # no generation models, no generation-file section # language models: type(srilm/irstlm), factors, order, file [lmodel-file] 1 0 5 /mnt/models/ar-en/language-model/en.qblm.mm 1 0 5 /mnt/models/en-ar/language-model/ar.lm.d1.blm.mm # limit on how many phrase translations e for each phrase f are loaded # 0 = all elements loaded [ttable-limit] 20 # distortion (reordering) files [distortion-file] 0-0 wbe-msd-bidirectional-fe-allff 6 /mnt/models/ar-en/reordering-table/reordering-table.wbe-msd-bidirectional-fe.gz 0-0 wbe-msd-bidirectional-fe-allff 6 /mnt/models/en-ar/reordering-model/reordering-table.wbe-msd-bidirectional-fe.gz # distortion (reordering) weight [weight-d] 0.3 0.3 # lexicalised distortion weights [weight-lr] 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 # language model weights [weight-l] 0.5000 0.5000 # translation model weights [weight-t] 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 # no generation models, no weight-generation section # word penalty [weight-w] -1 -1 [distortion-limit] 12 --------------------------------------------------------- So please can someone help me and rewrite this config file so it can work in version 1.0. And i need some python sample code of translation. I am using xmlrpc in python and earler I sent http request with: import xmlrpclib client = xmlrpclib.ServerProxy('http://localhost:8080') client.translate({'text': 'some text', 'system': 'en-ar'}) but now seems there is no more 'system' parameter and moses use always default settings.

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  • Grails - Language prefix in url mappings

    - by Art79
    Hi there im having problem with language mappings. The way i want it to work is that language is encoded in the url like /appname/de/mycontroller/whatever If you go to /appname/mycontroller/action it should check your session and if there is no session pick language based on browser preference and redirect to the language prefixed site. If you have session then it will display english. English does not have en prefix (to make it harder). So i created mappings like this: class UrlMappings { static mappings = { "/$lang/$controller/$action?/$id?"{ constraints { lang(matches:/pl|en/) } } "/$lang/store/$category" { controller = "storeItem" action = "index" constraints { lang(matches:/pl|en/) } } "/$lang/store" { controller = "storeItem" action = "index" constraints { lang(matches:/pl|en/) } } "/$controller/$action?/$id?"{ lang="en" constraints { } } "/store/$category" { lang="en" controller = "storeItem" action = "index" } "/store" { lang="en" controller = "storeItem" action = "index" } "/"(view:"/index") "500"(view:'/error') } } Its not fully working and langs are hardcoded just for now. I think i did something wrong. Some of the reverse mappings work but some dont add language. If i use link tag and pass params:[lang:'pl'] then it works but if i add params:[lang:'pl', page:2] then it does not. In the second case both lang and page number become parameters in the query string. What is worse they dont affect the locale so page shows in english. Can anyone please point me to the documentation what are the rules of reverse mappings or even better how to implement such language prefix in a good way ? THANKS

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  • Format External HD on Airport Extreme Base Station?

    - by David.Chu.ca
    I just got an Airport Extreme Base Station. I am planning to use this one replace my current Linksys router. This works fine. My another purpose of getting this device is to use its USB port to connect to several external HDs as my backup Time Machine. I can see one 500GB HD through Airport Base Station. However, I cannot format it by using Disk Utility. What I did is to connect the HD to my iMac directly first and then clean and format the disk by Disk Utility application. Then I move the HD to the Airport Base Station. After that I can designate the HD as my Time Machine destination. Is there any way to format the HD connected to Airport Base Station? Any issues to use an external HD through Airport Base Station for Time Machine backups?

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  • Hour-long shutdown duration "shutting down hyper-v virtual machine management service"

    - by icelava
    I have a Windows 2008 R2 server that is a Hyper-V host (Dell PowerEdge T300). Today for the first time I encountered an odd situation; i lost connection with one of the guest machines but logging on physically it seems the guest OS is still running but no longer contactable via the network. I tried to shut down the guest machine (Windows XP) but it would not shut down, getting stuck in a "Not responding" dialog box that cannot be dismissed. I used the Hyper-V management console to reset the machine and it could not get out of resetting state. I tried to save another Windows 2003 guest machine, and it would be progress with its Saving state (0%). The other running Windows 2003 guest was stuck in the logon dialog. My first suspicion is perhaps one of the Windows update patches this week (10 Nov 2011) may something to do with it, which was still pending a system restart. Well, since I could not do anything with Hyper-V i proceeded with the Windows Update restart, and now it is stuck half an hour at "Shutting down hyper-v virtual machine management service" Prior to restarting I did not observe any hard disk errors reported in the system event log; doubt it is a disk-related condition. Shall I force a hard reboot? UPDATE Ok so i left it hanging over an hour while attending to other matters, and thankfully the host cleanly restarted. I can operate the guest machines fine now. Phew. Hyper-V must have been crawling for some reason. The VMs have been observed to become slow in the past when the host has been up for a long duration (two weeks to a month), but never this slow. Would love to know what types of performance monitoring items i can observe to give a hint why this can happen. UPDATE 2012-02-13 In the months ever since, Hyper-V has stalled into this state another two times. It appears so randomly and without any error event logs to hint what is causing it enter this "drunkard" state. Just an Hyper-V management service timeout. Log Name: System Source: Service Control Manager Date: 13/2/2012 9:16:48 AM Event ID: 7043 Task Category: None Level: Error Keywords: Classic User: N/A Computer: elune Description: The Hyper-V Virtual Machine Management service did not shut down properly after receiving a preshutdown control. Event Xml: <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event"> <System> <Provider Name="Service Control Manager" Guid="{555908d1-a6d7-4695-8e1e-26931d2012f4}" EventSourceName="Service Control Manager" /> <EventID Qualifiers="49152">7043</EventID> <Version>0</Version> <Level>2</Level> <Task>0</Task> <Opcode>0</Opcode> <Keywords>0x8080000000000000</Keywords> <TimeCreated SystemTime="2012-02-13T01:16:48.882901900Z" /> <EventRecordID>567844</EventRecordID> <Correlation /> <Execution ProcessID="764" ThreadID="8484" /> <Channel>System</Channel> <Computer>elune</Computer> <Security /> </System> <EventData> <Data Name="param1">Hyper-V Virtual Machine Management</Data> </EventData> </Event> The only means out of it is to restart the system.

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  • running a web server with encrypted file system (all or part of it)

    - by Carlos
    Hi, I need a webserver (lamp) running inside a virtual machine (#1) running as a service (#2) in headless mode (#3) with part or the whole filesystem encrypted (#4). The virtual machine will be started with no user intervention and provide access to a web application for users in the host machine. Points #1,#2 and #3 are checked and proved to be working fine with Sun VirtualBox, so my question is for #4: Can I encrypt the all filesystem and still access the webserver (using a browser) or will grub ask me for a password? If encrypting the all filesystem is not an option, can I encrypt only /home and /var/www ? will apache/php be able to use files in /home or /var/www without asking for a password or mounting these partitions manually? Thanks

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  • How can I access a Web server in a VM from an iPad?

    - by Nick Haslam
    I have a virtual machine (running Windows Server 2012, if it's relevant), on VMware Workstation. It is running an Apache Tomcat web server, and I'm wanting to access that webserver from an iPad. Is this feasible, or even possible ? I have tried running Connectify Hotspot on the host machine, but that only gets me as far as being able to access a webpage on the host machine. It doesn't look to pass the connection through to the VM as they are on different subnets. Any thoughts are gratefully received.

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  • safe to setup NAS in virtual image with web server?

    - by Erik
    My current setup is Ubuntu Desktop, running Apache + MySQL + PHP stack. I use this image to host my small website to the outside world. I want to now run a virtual machine on the box, that will act as the FreeNAS box for my internal network. This sounds like a bad idea if the website gets hacked/attacked. Should I just give up and grab a dedicated machine instead? Can I instead virtualize the web server and NAS side by side on this machine?

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  • How should I start with Lisp?

    - by Gary Rowe
    I've been programming for years now, working my way through various iterations of Blub (BASIC, Assembler, C, C++, Visual Basic, Java, Ruby in no particular order of "Blub-ness") and I'd like to learn Lisp. However, I have a lot of intertia what with limited time (family, full time job etc) and a comfortable happiness with my current Blub (Java). So my question is this, given that I'm someone who would really like to learn Lisp, what would be the initial steps to get a good result that demonstrates the superiority of Lisp in web development? Maybe I'm missing the point, but that's how I would initially see the application of my Lisp knowledge. I'm thinking "use dialect A, use IDE B, follow instructions on page C, question your sanity after monads using counsellor D". I'd just like to know what people here consider to be an optimal set of values for A, B, C and perhaps D. Also some discussion on the relative merit of learning such a powerful language as opposed to, say, becoming a Rails expert. Just to add some more detail, I'll be developing on MacOS (or a Linux VM) - no Windows based approaches will be necessary, thanks. Notes for those just browsing by I'm going to keep this question open for a while so that I can offer feedback on the suggestions after I've been able to explore them. If you happen to be browsing by and feel you have something to add, please do. I would really welcome your feedback. Interesting links Assuming you're coming at Lisp from a Java background, this set of links will get you started quickly. Using Intellij's La Clojure plugin to integrate Lisp (videocast) Lisp for the Web Online version of Practical Common Lisp (c/o Frank Shearar) Land of Lisp a (+ (+ very quirky) game based) way in but makes it all so straightforward

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  • How should I start with Lisp?

    - by Gary Rowe
    I've been programming for years now, working my way through various iterations of Blub (BASIC, Assembler, C, C++, Visual Basic, Java, Ruby in no particular order of "Blub-ness") and I'd like to learn Lisp. However, I have a lot of intertia what with limited time (family, full time job etc) and a comfortable happiness with my current Blub (Java). So my question is this, given that I'm someone who would really like to learn Lisp, what would be the initial steps to get a good result that demonstrates the superiority of Lisp in web development? Maybe I'm missing the point, but that's how I would initially see the application of my Lisp knowledge. I'm thinking "use dialect A, use IDE B, follow instructions on page C, question your sanity after monads using counsellor D". I'd just like to know what people here consider to be an optimal set of values for A, B, C and perhaps D. Also some discussion on the relative merit of learning such a powerful language as opposed to, say, becoming a Rails expert. Just to add some more detail, I'll be developing on MacOS (or a Linux VM) - no Windows based approaches will be necessary, thanks. Notes for those just browsing by I'm going to keep this question open for a while so that I can offer feedback on the suggestions after I've been able to explore them. If you happen to be browsing by and feel you have something to add, please do. I would really welcome your feedback. Interesting links Assuming you're coming at Lisp from a Java background, this set of links will get you started quickly. Using Intellij's La Clojure plugin to integrate Lisp (videocast) Lisp for the Web Online version of Practical Common Lisp (c/o Frank Shearar) Land of Lisp a (+ (+ very quirky) game based) way in but makes it all so straightforward

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  • Google Webmaster tools Incorrect rel-alternate-hreflang implementation warning message

    - by Noam
    I'm getting this warning msg. in Google webmaster tools Incorrect rel-alternate-hreflang implementation In particular, there seems to be a problem with missing or incorrect bi-directional linking (when page A links with hreflang to page B, there must be a link back from B to A as well). This msg. seems pretty straight forward, but when checking their example pages, I'm not finding anything wrong. I'm using alternate for translation of main site menu, titles, etc.. In each page I have this: <link rel="alternate" hreflang="en" href="http://mydomain.com/page" /> <link rel="alternate" hreflang="jp" href="http://ja.mydomain.com/page" /> <link rel="alternate" hreflang="ko" href="http://ko.mydomain.com/page" /> <link rel="alternate" hreflang="th" href="http://th.mydomain.com/page" /> <link rel="alternate" hreflang="es" href="http://es.mydomain.com/page" /> <link rel="alternate" hreflang="pt" href="http://pt.mydomain.com/page" /> I've double checked this exists in all the 6 pages. This is the first time I've seen this msg although I've implemented this at least 6 months ago, and implementation hasn't changed. Is there any way to check a specific set of pages for these things? Am I missing something in my implementation? We're auto-redirecting people from a location to their specific language, and give them an option to manually change this. I've also just found out about the suggestion for Vary HTTP header - is that relevant and important here?

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  • What's the ethos of the programming profession?

    - by mac
    I am one of those people who became professional programmer by chance, rather than by choice: I moved to a country whose main language I couldn't speak, I knew how to code... and here I am a few years later. Because of this I never really gave much a thought about the ethos of being a programmer, and working as a freelance I neither had many occasions to discuss this with fellow colleagues. Among others, Dictionary.com define the word ethos as follows: The fundamental character or spirit of a culture; the underlying sentiment that informs the beliefs, customs, or practices of a group or society; dominant assumptions of a people or period. So my question is: How would you describe the ethos of being a programmer, and why would you say so? Please note that: my question is different than this and this other ones (although you might have chosen to become a programmer because of the programmer'ethos or you might think that part of the programmer ethos is about "programming being a meaningful profession"). beside the "how/what" part of the question, there is a "why" part too! :) I would appreciate if the answer could be based not only on the idealised vision of the hero-programmer, but also on real working and life experience. Thank you in advance for your time and contributions!

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  • Updating password hashing without forcing a new password for existing users

    - by Willem
    You maintain an existing application with an established user base. Over time it is decided that the current password hashing technique is outdated and needs to be upgraded. Furthermore, for UX reasons, you don't want existing users to be forced to update their password. The whole password hashing update needs to happen behind the screen. Assume a 'simplistic' database model for users that contains: ID Email Password How does one go around to solving such a requirement? My current thoughts are: create a new hashing method in the appropriate class update the user table in the database to hold an additional password field Once a user successfully logs in using the outdated password hash, fill the second password field with the updated hash This leaves me with the problem that I cannot reasonable differentiate between users who have and those who have not updated their password hash and thus will be forced to check both. This seems horribly flawed. Furthermore this basically means that the old hashing technique could be forced to stay indefinitely until every single user has updated their password. Only at that moment could I start removing the old hashing check and remove the superfluous database field. I'm mainly looking for some design tips here, since my current 'solution' is dirty, incomplete and what not, but if actual code is required to describe a possible solution, feel free to use any language.

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  • What's your most controversial programming opinion?

    - by Jon Skeet
    This is definitely subjective, but I'd like to try to avoid it becoming argumentative. I think it could be an interesting question if people treat it appropriately. The idea for this question came from the comment thread from my answer to the "What are five things you hate about your favorite language?" question. I contended that classes in C# should be sealed by default - I won't put my reasoning in the question, but I might write a fuller explanation as an answer to this question. I was surprised at the heat of the discussion in the comments (25 comments currently). So, what contentious opinions do you hold? I'd rather avoid the kind of thing which ends up being pretty religious with relatively little basis (e.g. brace placing) but examples might include things like "unit testing isn't actually terribly helpful" or "public fields are okay really". The important thing (to me, anyway) is that you've got reasons behind your opinions. Please present your opinion and reasoning - I would encourage people to vote for opinions which are well-argued and interesting, whether or not you happen to agree with them.

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  • An alternative to multiple inheritance when creating an abstraction layer?

    - by sebf
    In my project I am creating an abstraction layer for some APIs. The purpose of the layer is to make multi-platform easier, and also to simplify the APIs to the feature set that I need while also providing some functionality, the implementation of which will be unique to each platform. At the moment, I have implemented it by defining and abstract class, which has methods which creates objects that implement interfaces. The abstract class and these interfaces define the capabilities of my abstraction layer. The implementation of these in my layer should of course be arbitrary from the POV view of my application, but I have done it, for my first API, by creating chains of subclasses which add more specific functionality as the features of the APIs they expose become less generic. An example would probably demonstrate this better: //The interface as seen by the application interface IGenericResource { byte[] GetSomeData(); } interface ISpecificResourceOne : IGenericResource { int SomePropertyOfResourceOne {get;} } interface ISpecificResourceTwo : IGenericResource { string SomePropertyOfResourceTwo {get;} } public abstract class MyLayer { ISpecificResourceOne CreateResourceOne(); ISpecificResourceTwo CreateResourceTwo(); void UseResourceOne(ISpecificResourceOne one); void UseResourceTwo(ISpecificResourceTwo two); } //The layer as created in my library public class LowLevelResource : IGenericResource { byte[] GetSomeData() {} } public class ResourceOne : LowLevelResource, ISpecificResourceOne { int SomePropertyOfResourceOne {get{}} } public class ResourceTwo : ResourceOne, ISpecificResourceTwo { string SomePropertyOfResourceTwo {get {}} } public partial class Implementation : MyLayer { override UseResourceOne(ISpecificResourceOne one) { DoStuff((ResourceOne)one); } } As can be seen, I am essentially trying to have two inheritance chains on the same object, but of course I can't do this so I simulate the second version with interfaces. The thing is though, I don't like using interfaces for this; it seems wrong, in my mind an interface defines a contract, any class that implements that interface should be able to be used where that interface is used but here that is clearly not the case because the interfaces are being used to allow an object from the layer to masquerade as something else, without the application needing to have access to its definition. What technique would allow me to define a comprehensive, intuitive collection of objects for an abstraction layer, while their implementation remains independent? (Language is C#)

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  • Best way to go for simple online multi-player games?

    - by Mr_CryptoPrime
    I want to create a trivia game for my website. The graphic design does not have to be too fancy, probably no more advanced than a typical flash game. It needs to be secure because I want users to be able to play for real money. It also needs to run fast so users don't spend their time frustrated with game freezing. Compatibility, as with almost all online products, is key because of the large target market. I am most acquainted with Java programming, but I don't want to do it in Java if there is something much better. I am assuming I will have to utilize a variety of different languages in order for everything to come together. If someone could point out the main structure of everything so I could get a good start that would be great! 1) Language choice for simple secure online multiplayer games? 2) Perhaps use a database like MySQL, stored on a secure server for the trivia questions? 3) Free educational resources and even simpler projects to practice? Any ideas or suggestions would be helpful...Thanks!

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  • What are my choices for server side sandboxed scripting?

    - by alfa64
    I'm building a public website where users share data and scripts to run over some data. The scripts are run serverside in some sort of sandbox without other interaction this cycle: my Perl program reads from a database a User made script, adds the data to be processed into the script ( ie: a JSON document) then calls the interpreter, it returns the response( a JSON document or plain text), i save it to the database with my perl script. The script should be able to have some access to built in functions added to the scripting language by myself, but nothing more. So i've stumbled upon node.js as a javascript interpreter, and and hour or so ago with Google's V8(does v8 makes sense for this kind of thing?). CoffeeScript also came to my mind, since it looks nice and it's still Javascript. I think javascript is widespread enough and more "sandboxeable" since it doesn't have OS calls or anything remotely insecure ( i think ). by the way, i'm writing the system on Perl and Php for the front end. To improve the question: I'm choosing Javascript because i think is secure and simple enough to implement with node.js, but what other alternatives are for achieving this kind of task? Lua? Python? I just can't find information on how to run a sandboxed interpreter in a proper way.

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  • Are null references really a bad thing?

    - by Tim Goodman
    I've heard it said that the inclusion of null references in programming languages is the "billion dollar mistake". But why? Sure, they can cause NullReferenceExceptions, but so what? Any element of the language can be a source of errors if used improperly. And what's the alternative? I suppose instead of saying this: Customer c = Customer.GetByLastName("Goodman"); // returns null if not found if (c != null) { Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } You could say this: if (Customer.ExistsWithLastName("Goodman")) { Customer c = Customer.GetByLastName("Goodman") // throws error if not found Console.WriteLine(c.FirstName + " " + c.LastName + " is awesome!"); } else { Console.WriteLine("There was no customer named Goodman. How lame!"); } But how is that better? Either way, if you forget to check that the customer exists, you get an exception. I suppose that a CustomerNotFoundException is a bit easier to debug than a NullReferenceException by virtue of being more descriptive. Is that all there is to it?

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  • pass by reference or pass by value?

    - by Sven
    When learning a new programming language, one of the possible roadblocks you might encounter is the question whether the language is, by default, pass-by-value or pass-by-reference So here is my question to all of you, in your favorite language, how is it actually done? and what are the possible pitfalls? your favorite language can, of course, be anything you have ever played with: popular, obscure, esoteric, new, old ...

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  • backup of KVM VM's running on Ubuntu 12.4.1 precise edition from a remote machine

    - by Dr. Death
    I am creating a library API which will take the backup of all the VM's running on KVM hypervisor. My VM's can be of any type. I am taking this backup from a remote machine and need to put the backup at remote server. I have KVM, Libvirt installed on my system. Some of my VM's are LVM based and some are normal VM's running on KVM. I research and found out an excellent perl script for taking the backup http://pof.eslack.org/2010/12/23/best-solution-to-fully-backup-kvm-virtual-machines/ but since I am developing this library in C++ I cannot use it however it has given me a good understanding of how it will work. One thing I didnot able to sort out is if my VM's are not created using virt-manager or are created using any other tool them virsh system list command does not give them in the list of running VM's however they are running perfectly on my KVM server. Is there a way to list these VM's in my system list anyhow? secondly, when I am taking backup from the remote machine I am getting out of my ssh mode as soon as my libvirt command finishes and for every command I need to ssh again, Is there a way that I do not need to ssh each and every time? I have already used the rsa key for ssh but when once my command finishes my control moves to the remote machine again and try to find out my source VM location in remote machine's local drives which in turn fails it. here is the main problem I am facing. also for the LVM based VM I am able to take the live backup but for non LVM based my machines are getting suspended and not been able to take the live backup. Since my library will work on the remote machine only I might not know the VM's configruation on the KVM server. so need to make it consistent for all the VM's. Please share any thing related to this issue so that I may be able to take the live backup of the non lvm vm's also. I'll update my working and any research findings time to time to all of you. Thanks in advance for your suggestions in these regards.

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  • Are there any applications written in the Io programming language? (Or, distributing Io applications

    - by Rayne
    I've recently become interested in prototype-based OOP, and I've been playing with Io and Ioke. Distributing an application with Ioke is simple. It's on the JVM. Need I say more? However, I'm absolutely stumped as to how one would distribute an Io application, especially on Windows. It's not like you can have end-users compile Io to run your application. I was actually shocked the Io has gone for 8 years without forming some sort of standards for things like distribution. Ruby has gems, Java has jars, and so on. The worse thing about it is, I can't find a single application written in Io to maybe steal ideas on distribution from. Maybe I suck at google searching (Io is a horrible search name, by the way ;P). Is there any sort of canonical way to distribute Io applications? Are there even any Io applications in existence, or am I just missing the point? I'm not sure if this should be community wiki or not. If you think it should, comment and let me know.

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