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  • Help needed with pyparsing [closed]

    - by Zearin
    Overview So, I’m in the middle of refactoring a project, and I’m separating out a bunch of parsing code. The code I’m concerned with is pyparsing. I have a very poor understanding of pyparsing, even after spending a lot of time reading through the official documentation. I’m having trouble because (1) pyparsing takes a (deliberately) unorthodox approach to parsing, and (2) I’m working on code I didn’t write, with poor comments, and a non-elementary set of existing grammars. (I can’t get in touch with the original author, either.) Failing Test I’m using PyVows to test my code. One of my tests is as follows (I think this is clear even if you’re unfamiliar with PyVows; let me know if it isn’t): def test_multiline_command_ends(self, topic): output = parsed_input('multiline command ends\n\n',topic) expect(output).to_equal( r'''['multiline', 'command ends', '\n', '\n'] - args: command ends - multiline_command: multiline - statement: ['multiline', 'command ends', '\n', '\n'] - args: command ends - multiline_command: multiline - terminator: ['\n', '\n'] - terminator: ['\n', '\n']''') But when I run the test, I get the following in the terminal: Failed Test Results Expected topic("['multiline', 'command ends']\n- args: command ends\n- command: multiline\n- statement: ['multiline', 'command ends']\n - args: command ends\n - command: multiline") to equal "['multiline', 'command ends', '\\n', '\\n']\n- args: command ends\n- multiline_command: multiline\n- statement: ['multiline', 'command ends', '\\n', '\\n']\n - args: command ends\n - multiline_command: multiline\n - terminator: ['\\n', '\\n']\n- terminator: ['\\n', '\\n']" Note: Since the output is to a Terminal, the expected output (the second one) has extra backslashes. This is normal. The test ran without issue before this piece of refactoring began. Expected Behavior The first line of output should match the second, but it doesn’t. Specifically, it’s not including the two newline characters in that first list object. So I’m getting this: "['multiline', 'command ends']\n- args: command ends\n- command: multiline\n- statement: ['multiline', 'command ends']\n - args: command ends\n - command: multiline" When I should be getting this: "['multiline', 'command ends', '\\n', '\\n']\n- args: command ends\n- multiline_command: multiline\n- statement: ['multiline', 'command ends', '\\n', '\\n']\n - args: command ends\n - multiline_command: multiline\n - terminator: ['\\n', '\\n']\n- terminator: ['\\n', '\\n']" Earlier in the code, there is also this statement: pyparsing.ParserElement.setDefaultWhitespaceChars(' \t') …Which I think should prevent exactly this kind of error. But I’m not sure. Even if the problem can’t be identified with certainty, simply narrowing down where the problem is would be a HUGE help. Please let me know how I might take a step or two towards fixing this.

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  • Refresh resources in Windows Phone 7 app

    - by Eugene
    I have a Windows Phone app that relies on an XML data file that comes packaged with the app. In the next version of my app, the XML file will be updated, how do I update the data file once per app update? I thought I could change the file name in the isolated storage, but that would leave trash behind. I could also check for exceptions when I load the XML file, but are there any other, more elegant ways?

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  • Naming a predicate: "precondition" or "precondition_is_met"?

    - by RexE
    In my web app framework, each page can have a precondition that needs to be satisfied before it can be displayed to the user. For example, if user 1 and user 2 are playing a back-and-forth role-playing game, user 2 needs to wait for user 1 to finish his turn before he can take his turn. Otherwise, the user is displayed a waiting page. This is implemented with a predicate: def precondition(self): return user_1.completed_turn The simplest name for this API is precondition, but this leads to code like if precondition(): ..., which is not really obvious. Seems to me like it is more accurate to call it precondition_is_met(), but not sure about that either. Is there a best practice for naming methods like this?

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  • Sorting a Linked List [closed]

    - by Mohit Sehgal
    I want to sort a linked list. Here Node is class representing a node in a Linked List I have written a code to bubble sort a linked list. Program does not finishes execution. Kindly point out the mistakes. class Node { public: int data; public: Node *next; Node() { data=0;next=0; } Node(int d) { data=d; } void setData(int d) { data=d; } void print() { cout<<data<<endl; } bool operator==(Node n) { return this->data==n.data; } bool operator >(Node d) { if((this->data) > (d.data)) return true; return false; } }; class LList { public: int noOfNodes; Node *start;/*Header Node*/ LList() { start=new Node; noOfNodes=0;start=0; } void addAtFront(Node* n) { n->next=(start); start=n; noOfNodes++; } void addAtLast(Node* n) { Node *cur=(start); n->next=NULL; if(start==NULL) { start=n; noOfNodes++; return; } while(cur->next!=NULL) { cur=cur->next; } cur->next=n; noOfNodes++; } void addAtPos(Node *n,int pos) { if(pos==1) { addAtFront(n);return; } Node *cur=(start); Node *prev=NULL; int curPos=0; n->next=NULL; while(cur!=NULL) { curPos++; if(pos==curPos+1) { prev=cur; } if(pos==curPos) { n->next=cur; prev->next=n; break; } cur=cur->next; } noOfNodes++; } void removeFirst() { Node *del=start; start=start->next; delete del; noOfNodes--; return; } void removeLast() { Node *cur=start,*prev=NULL; while(cur->next!=NULL) { prev=cur; cur=cur->next; } prev->next=NULL; Node *del=cur->next; delete del; noOfNodes--; return; } void removeNodeAt(int pos) { if(pos<1) return; if(pos==1) { removeFirst();return;} int curPos=1; Node* cur=start->next; Node* prev=start; Node* del=NULL; while(curPos<pos&&cur!=NULL) { curPos++; if(curPos==pos) { del=cur; prev->next=cur->next; cur->next=NULL; delete del; noOfNodes--; break; } prev=prev->next; cur=cur->next; } } void removeNode(Node *d) { Node *cur=start; if(*d==*cur) { removeFirst();return; } cur=start->next; Node *prev=start,*del=NULL; while(cur!=NULL) { if(*cur==*d) { del=cur; prev->next=cur->next; delete del; noOfNodes--; break; } prev=prev->next; cur=cur->next; } } int getPosition(Node data) { int pos=0; Node *cur=(start); while(cur!=NULL) { pos++; if(*cur==data) { return pos; } cur=cur->next; } return -1;//not found } Node getNode(int pos) { if(pos<1) return -1;// not a valid position else if(pos>noOfNodes) return -1; // not a valid position Node *cur=(start); int curPos=0; while(cur!=NULL) { if(++curPos==pos) return *cur; cur=cur->next; } } void reverseList()//reverse the list { Node* cur=start->next; Node* d=NULL; Node* prev=start; while(cur!=NULL) { d=cur->next; cur->next=start; start=cur; prev->next=d; cur=d; } } void sortBubble() { Node *i=start,*j=start,*prev=NULL,*temp=NULL,*after=NULL; int count=noOfNodes-1;int icount=0; while(i->next!=NULL) { j=start; after=j->next; icount=0; while(++icount!=count) { if((*j)>(*after)) { temp=after->next; after->next=j; prev->next=j->next; j->next=temp; prev=after; after=j->next; } else{ prev=j; j=after; after=after->next; } } i=i->next; count--; } } void traverse() { Node *cur=(start); int c=0; while(cur!=NULL) { // cout<<"start"<<start; c++; cur->print(); cur=cur->next; } noOfNodes=c; } ~LList() { delete start; } }; int main() { int n; cin>>n; int d; LList list; Node *node; Node *temp=new Node(2123); for(int i=0;i<n;i++) { cin>>d; node=new Node(d); list.addAtLast(node); } list.addAtPos(temp,1); cout<<"traverse\n"; list.traverse(); temp=new Node(12); list.removeNode(temp); cout<<"12 removed"; list.traverse(); list.reverseList(); cout<<"\nreversed\n"; list.traverse(); cout<<"bubble sort\n"; list.sortBubble(); list.traverse(); getch(); delete node; return 0; }

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  • Automatic Appointment Conflict Resolution

    - by Thomas
    I'm trying to figure out an algorithm for resolving appointment times. I currently have a naive algorithm that pushes down conflicting appointments repeatedly, until there are no more appointments. # The appointment list is always sorted on start time appointment_list = [ <Appointment: 10:00 -> 12:00>, <Appointment: 11:00 -> 12:30>, <Appointment: 13:00 -> 14:00>, <Appointment: 13:30 -> 14:30>, ] Constraints are that appointments: cannot be after 15:00 cannot be before 9:00 This is the naive algorithm for i, app in enumerate(appointment_list): for possible_conflict in appointment_list[i+1:]: if possible_conflict.start < app.end: difference = app.end - possible_conflict.start possible_conflict.end += difference possible_conflict.start += difference else: break This results in the following resolution, which obviously breaks those constraints, and the last appointment will have to be pushed to the following day. appointment_list = [ <Appointment: 10:00 -> 12:00>, <Appointment: 12:00 -> 13:30>, <Appointment: 13:30 -> 14:30>, <Appointment: 14:30 -> 15:30>, ] Obviously this is sub-optimal, It performs 3 appointment moves when the confict could have been resolved with one: if we were able to push the first appointment backwards, we could avoid moving all the subsequent appointments down. I'm thinking that there should be a sort of edit-distance approach that would calculate the least number of appointments that should be moved in order to resolve the scheduling conflict, but I can't get the a handle on the methodology. Should it be breadth-first or depth first solution search. When do I know if the solution is "good enough"?

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  • Should mock objects for tests be created at a high or low level

    - by Danack
    When creating unit tests for those other objects, what is the best way to create mock objects that provide data to other objects. Should they be created at a 'high level' and intercept the calls as soon as possible, or should they be done at a 'low level' and so make as much as the real code still be called? e.g. I'm writing a test for some code that requires a NoteMapper object that allows Notes to be loaded from the DB. class NoteMapper { function getNote($sqlQueryFactory, $noteID) { // Create an SQL query from $sqlQueryFactory // Run that SQL // if null // return null // else // return new Note($dataFromSQLQuery) } } I could either mock this object at a high level by creating a mock NoteMapper object, so that there are no calls to the SQL at all e.g. class MockNoteMapper { function getNote($sqlQueryFactory, $noteID) { //$mockData = {'Test Note title', "Test note text" } // return new Note($mockData); } } Or I could do it at a very low level, by creating a MockSQLQueryFactory that instead of actually querying the database just provides mock data back, and passing that to the current NoteMapper object. It seems that creating mocks at a high level would be easier in the short term, but that in the long term doing it at a low level would be more powerful and possibly allow more automation of tests e.g. by recording data in an out of a DB and then replaying that data for tests. Is there a recommended way of creating mocks? Are there any hard and fast rules about which are better, or should they both be used where appropriate?

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  • Using automated bdd-gui-tests to keep user-documentation-screenshots up do date?

    - by k3b
    Are there developpers out there, who (ab)use the CaptureScreenshot() function of their automated gui-tests to also create uptodate-screenshots for the userdocumentation? Background: Whithin the lifetime of an application, its gui-elements are constantly changing. It makes a lot of work to keep the userdocumentation uptodate, especially if the example data in the pictures should match the textual description. If you already have automated bdd-gui-tests why not let them take screenshots at certain points? I am currently playing with webapps in dotnet+specflow+selenium, but this topic also applies to other bdd-engines (JRuby-Cucumber, mspec, rspec, ...) and gui-test-Frameworks (WaitN, WaitR, MsWhite, ....) Any experience, thoughts or url-links to this topic would be helpfull. How is the cost/benefit relation? Is it worth the efford? What are the Drawbacks? See also: Is it practical to retroactively write specifications documenting a system via automated acceptance tests?

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  • High Usage of RAM by wxPython's GUI and need some advice to reduce it

    - by user67024
    I've recently developed a GUI in wxPython for windows platform. It contains a five tabs, 4 of them are just richTextCtrl boxes and the other one has controls for uploading files, buttons, textctrls, a slider etc.. As I was new to GUI development in Python, I used wxFormBuilder to generate some of the code using a good amount of sizers. So, now the problem is that the GUI starts off with a initial memory of around 40MB which is too much for such a simple application (Or so I think) . Also, when the functions handling the functions use huge lists as the program is for debugging large data logs and identifying the problems in'em implying that I can't afford memory for GUI. So, how can I reduce that start working memory size? Is it a general issue in wxPython? And currently trying use profilers but not sure if it's going to help.

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  • Commercial product using a GPL OS

    - by pfried
    we are planning to create a commercial product. The product consists of come MCUs and a small computer (we are developping on a raspberry pi at the moment). The computer needs an operating system as we would like keep things like WLAN and booting as simple as possible. We create some software running on this computer (node.js application). The most operating systems like Arch Linux are licenced under the GPL. The product we would sell contains the computer with preinstalled OS and software. This system operates as a central access point to MCU devices and is able to control them. We use other's software in our product. We do not modify their source code. The product (the computer part) consists of a computer, an OS and software we create. How does the use of an OS affect our own code (licence)? Is there a possibility of avoiding GPL for our own code? eg. shipping the software seperated? Are there any effects to other components of our product, eg. the MCU part? The node.js application delivers a WebApp to the client where it is executed. Are there any effects (As we would like to sell parts of the code as an additional App on the App Stores)? I know we make use of the work of the community and i respect this. The problem is: The software alone is kind of useless without the MCU devices. I do not expect a legal advice.

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  • Index independent character comparison within text blocks

    - by Michael IV
    I have the following task: developing a program where there is a block of sample text which should be typed by user. Any typos the user does during the test are registered. Basically, I can compare each typed char with the sample char based on caret index position of the input, but there is one significant flaw in such a "naive" approach. If the user typed mistakenly more letters than a whole string has, or inserted more white spaces between the string than should be, then the rest of the comparisons will be wrong because of the index offsets added by the additional wrong insertions. I have thought of designing some kind of parser where each string (or even a char ) is tokenized and the comparisons are made "char-wise" and not "index-wise," but that seems to me like an overkill for such a task. I would like to get a reference to possibly existing algorithms which can be helpful in solving this kind of problem.

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  • How a .NET Programmer learn Big Data/Hadoop? [on hold]

    - by Smith Pascal Jr.
    I have been ASP.NET developer for sometime now and I have been reading a lot about Big Data- Hadoop and its future as to how it is the next technology in IT and how it would be useful to create million of jobs in US and elsewhere in the world. Now since Hadoop is an open source big data tool which is managed by Apache Server Foundation Group, I'm assuming I have to be well aware of JAVA - Correct me if I'm wrong. Moreover, How a .NET programmer can learn Big Data and its related technologies and can work professionally full time into this technology? What challenges and opportunities does a .NET professional face while changing the technology platform? Please advice. Thanks

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  • Career guidance/advice for Junior-level Software Engineer [closed]

    - by John Do
    I have quite a few questions on my mind, so please bare with me. Please don't feel obligated to answer all of them, any as you choose will do. I'd appreciate if you could share some insight on any of these. Before I begin, some context: I currently have almost two years of professional experience as a Software Engineer, mainly developing software in Java. At this point, I feel that I have reached the peak in my career growth at the current company I am at and therefore I am looking for a new job, ideally again, as a Software Engineer. I have been interviewing for the past few months casually but have not had luck with companies I have a passion for. So, in no particular order - 1) In general, what are your thoughts on having graduate degrees in CS / Software Engineering. How much does it influence a salary increase, and do you think it's beneficial when working on real-world problems? I get the sense that a graduate degree in the field is trivial unless you really have a passion for research. 2) In general, in professional practice, how often had you have to write your own data structures and "complex" algorithms from scratch? In my own work, I have found myself relying mainly on third-party frameworks and the Java standard library to implement solutions as per business requirements. What are your thoughts on this? 3) In terms of resume, I feel the most ambivalent here. I want to be able to "blemish" my resume to a certain extent so that it stands out from others', but at the same time I do not want to over-exagerate my abilities. How do you strike a balance here? For example: I say that I am proficient in Java with data structures and algorithms. This is obviously a subjective and relative statement. I've taken the classes in my undergrad, and I've applied it in my work experience. What I feel as "prociency" can be seen as junior-level to others. How do you know what to say? Most of the time, recruiters (with no technical background) will be looking for keywords that stand out. This leads me to my next question (4). 4) Just from interviewing for the past few months (and getting plenty of rejections), I've come to realize that I may not be as proficient in data structures and algorithms as I thought I was. Do you think it's a good idea to remove the "proficient in java/data structure and algorithms"? I feel that being too hoenst on the resume will impede me from scoring opportunities to even have an interview with top-notch companies. What are your thoughts? 5) What is the absolute "must-have" knowledge going into a technical interview? I've been practicing several algorithmic and data sturcture problems now, and I feel that my abilities to solve arbitrary problems efficiently has not gotten significantly better. Do you think these abilities are something innate - it's either you have in you, or you don't? How can you teach yourself to learn, if you will? 6) How easy is it to go from industry/function to the next? I work mainly with backend technologies and I'm now interested in working with the frontend, i.e javascript,jquery,php or even mobile development. In your own experience, how did you not get pidgeon holed in your career? I feel that the choices you make now ultimately decide your future. As cliche as it sounds, I think it may be true. Here's what I mean: you've worked mainly as a backend engineer, people are interested in you doing the same thing since you've already accumulated experience in that function. How do get experience in a new function if people won't accept you because you don't already have it? It's a catch 22, you see... Are side projects the only real way to help you move from one function to another that you're truly interested in? For example: I could start writing my own mobile applications, even though I've worked mainly on the backend. Thanks so much for the long read. As a relatively new engineer to the real world, I am very humble and would like those who are experienced to shed some light. Thank you so much.

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  • Theory Of A Weird Thought - Forms Submission

    - by user2738336
    In theory, if you were to open two computers that were perfectly synced together on a website that has a form. This form has fields where say for example the username has to be unique. Assuming both computers have the same information on the form, and in theory let's say that the submit button was pressed at the same time, and that these two computers have the exact same build and internet speed and the same response time from the server, whose information would be submitted to the database and whose information would be denied knowing the username field is unique.

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  • Spring can commit Transaction in finally block with RunTimeException in try block [migrated]

    - by Chance Lai
    The project used Spring + Hibernate Sample code: public void method(){ try{ dao.saveA(entityA); throw RuntimeException; dao.saveB(entityB); }catch(RuntimeException e){ throw e; }finally{ dao.saveC(entityC) } } Finally, just entityC will be saved in database in test. I think saveA, saveB, saveC in the same transaction,they should not be committed. In this case, I want to know why entityC is committed. How does Spring do this in the finally block?

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  • How to achieve a loosely coupled REST API but with a defined and well understood contract?

    - by BestPractices
    I am new to REST and am struggling to understand how one would properly design a REST system to both allow for loose coupling but at the same time allow a consumer of a REST API to understand the API. If, in my client code, I issue a GET request for a resource and get back XML, how do I know what to do with that xml? e.g. if it contains <fname>John</fname><lname>Smith</lname> how do I know that these refer to the concept of "first name", "last name"? Is it up to the person writing the REST API to define in documentation some place what each of the XML fields mean? What if producer of the API wants to change the implementation to be <firstname> instead of <fname>? How do they do this and notify their consumers that this change occurred? Or do the consumers just encounter the error and then look at the payload and figure out on their own that it changed? I've read in REST in Practice that using a WADL tool to create a client implementation based on the WADL (and hide the fact that you're doing a distributed call) is an "anti-pattern". But I was planning to do this-- at least then I would have a statically typed API call that, if it changed, I would know at compile time and not at run time. Why is this a bad thing to generate client code based on a WADL? And how do I know what to do with the links that returned in the response of a POST to a REST API? What defines this contract and gives true meaning to what each link will do? Please help! I dont understand how to go from statically-typed or even SOAP/RPC to REST!

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  • Practicing Java Swing

    - by user1265125
    I've been learning Java by myself through many different online and offline resources. I just finished some basic practice and theoretical knowledge of Swing. Now, to become good at it I need some practice problems which would test my Swing skills, including GUI Building, listeners etc. But I can't figure out where to find such questions/problems for my practice. Do you guys know of an online resource? Some book would also do...

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  • Overloading interface buttons, what are the best practices?

    - by XMLforDummies
    Imagine you'll have always a button labeled "Continue" in the same position in your app's GUI. Would you rather make a single button instance that takes different actions depending on the current state? private State currentState = State.Step1; private ContinueButton_Click() { switch(currentState) { case State.Step1: DoThis(); currentState = State.Step2; break; case State.Step2: DoThat(); break; } } Or would you rather have something like this? public Form() { this.ContinueStep2Button.Visible = false; } private ContinueStep1Button_Click() { DoThis(); this.ContinueStep1Button.Visible = false; this.ContinueStep2Button.Visible = true; } private ContinueStep2Button_Click() { DoThat(); }

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  • Recruiters intentionally present one good candidate for an available job

    - by Jeff O
    Maybe they do it without realizing. The recruiter's goal is to fill the job as soon as possible. I even think they feel it is in their best interest that the candidate be qualified, so I'm not trying to knock recruiters. Aren't they better off presenting 3 candidates, but one clearly stands out? The last thing they want from their client is a need to extend the interview process because they can't decide. If the client doesn't like any of them, you just bring on your next good candidate. This way they hedge their bet a little. Any experience, insight or ever heard of a head-hunter admit this? Does it make sense? There has to be a reason why the choose such unqualified people. I've seen jobs posted that clearly state they want someone with a CS degree and the recruiter doesn't take it literally. I don't have a CS degree or Java experience and still they think I'm a possible fit.

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  • How to Get Myself Up to Speed in Building a Java Web App

    - by Damian Wells
    I'm a new developer at a fairly large company and I'm working on a Java Web Application with a senior developer there. The Web App is built on top of an IBM stack (RAD, DB2, WebSphere) and basically uses JSPs and Servlets. The Web App is an internal tool to be used by employees to manage data coming from Excel files. So, there are lots of database interaction going around like SQL commands. My question is: I don't know much about JavaEE as a whole and only know a little about JSPs and Servlets and I would like to get myself up to speed so I can understand and contribute to the Web App as fast as I could. What resources (tutorials, links, etc) should I be looking at? Am I supposed to get a book about JavaEE or something that focuses just on JSPs and Servlets?

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  • Inspecting the model in a Rails application

    - by Matt Sherman
    I am learning some Ruby on Rails, and am a newbie. Most of my background is in ASP.net MVC on the back end. As I play with a basic scaffold project, I wonder about this case: you jump into an established Rails project and want to get to know the model. Based on what I have seen so far (again, simple scaffold), the properties for a given class are not immediately revealed. I don't see property accessors on the model classes. I do understand that this is because of the dynamic nature of Ruby and such things are not necessary or even perhaps desirable. Convention over code, I get that. (Am familiar with dynamic concepts, mostly via JS.) But if I am somewhere off in a view, and want to quickly know whether the (eg) Person object has a MiddleName property, how would I find that out? I don't have to go into the migrations, do I?

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  • Trying to use OpenGL in Java on Netbeans but getting an error. Please help [migrated]

    - by Steven Rogers
    I am on a Mac running Netbeans 6.9. I downloaded and installed LWJGL using this tutorial down to the letter: http://lwjgl.org/wiki/index.php?title=Setting_Up_LWJGL_with_NetBeans I finished the installation and copied sample code to see if my system is working. I got a bug, and was not sure if it was because of faulty code or i was doing something wrong. So i shortened down the code to this little simple bit: package javaopengl; import org.lwjgl.Sys; import org.lwjgl.opengl.Display; //Testing public class Main { public static void main(String[] args) { boolean fullscreen = (args.length == 1 && args[0].equals("-fullscreen")); try { Display.create(); Display.destroy(); } catch (Exception e) { e.printStackTrace(System.err); } System.exit(0); } } But i still get the same error, this is the error that i get: run: Exception in thread "main" java.lang.NoClassDefFoundError: = Caused by: java.lang.ClassNotFoundException: = at java.net.URLClassLoader$1.run(URLClassLoader.java:202) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:306) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) Java Result: 1 BUILD SUCCESSFUL (total time: 0 seconds) I am not sure what exactly is going on, Would you please tell me what is going on and how to fix it? It would be greatly appreciated, and thank you. Note: When i am looking at the text in the development environment, it does not show those red lines indicating there are any errors.

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  • Discuss: PLs are characterised by which (iso)morphisms are implemented

    - by Yttrill
    I am interested to hear discussion of the proposition summarised in the title. As we know programming language constructions admit a vast number of isomorphisms. In some languages in some places in the translation process some of these isomorphisms are implemented, whilst others require code to be written to implement them. For example, in my language Felix, the isomorphism between a type T and a tuple of one element of type T is implemented, meaning the two types are indistinguishable (identical). Similarly, a tuple of N values of the same type is not merely isomorphic to an array, it is an array: the isomorphism is implemented by the compiler. Many other isomorphisms are not implemented for example there is an isomorphism expressed by the following client code: match v with | ((?x,?y),?z = x,(y,z) // Felix match v with | (x,y), - x,(y,z) (* Ocaml *) As another example, a type constructor C of int in Felix may be used directly as a function, whilst in Ocaml you must write a wrapper: let c x = C x Another isomorphism Felix implements is the elimination of unit values, including those in tuples: Felix can do this because (most) polymorphic values are monomorphised which can be done because it is a whole program analyser, Ocaml, for example, cannot do this easily because it supports separate compilation. For the same reason Felix performs type-class dispatch at compile time whilst Haskell passes around dictionaries. There are some quite surprising issues here. For example an array is just a tuple, and tuples can be indexed at run time using a match and returning a value of a corresponding sum type. Indeed, to be correct the index used is in fact a case of unit sum with N summands, rather than an integer. Yet, in a real implementation, if the tuple is an array the index is replaced by an integer with a range check, and the result type is replaced by the common argument type of all the constructors: two isomorphisms are involved here, but they're implemented partly in the compiler translation and partly at run time.

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  • CMS vs Admin Panel?

    - by Bob
    Okay, so this probably seems like an unusual, more grammar related question, but I was unsure of what to call it. If you use a software such as vBulletin or MyBB or even Blogger and you're the administrator (or other, lesser position such as moderator) of the forum, or publisher/author of the blog, you generally have access to something of an "admin panel". For example, vBulletin's admin panel looks like this and Blogger's admin panel looks something like this. While they both look different and do different things, the goal is fundamentally the same: to provide the user with a method for adding, modifying, or deleting content... to let them control and administrate their forum or blog. Also, they're both made specifically by the company for use in a specific product. Now, there's also options like Drupal. It seems to offer quite a bit more and be quite a bit more generalized. How does something like this work? If you were freelancing, would you deploy a website with Drupal, or would it be something the client might already have installed on their own server? I've never really used Drupal, only heard about it, so please let me know. Also, there seems to be other options like cPanel, a sort of global CMS that allows you to administrate over your entire website. How do those work in comparison to Drupal, or the administrative panels with vBulletin? They seem to serve related, but different purposes. Basically, what is the norm? If I'm developing a web application for a group that needs to be able to edit their website without the need to go into the code or the database (or rather, wants to act in a graphical, easy-to-use content-management/admin panel), would it also be necessary to write my own miniature admin panel? Or would I be able to send them off knowing that they have cPanel? Or could something like Drupal fill this void? Again, I'm a little new to web development, and I'm working on planning out my first, real, large website. So I need a little advice on the standards and expectations for web development - security and coding practices aside, what should I be looking for as far as usability and administration for the client (who will be running the site once I'm done creating the website)? Any extra tips would also be appreciated! Oh, and just a little bit: I'm writing the website using Ruby on the Sinatra framework (both Ruby and Sinatra are things I'm fairly comfortable with) and I'm not being paid to make the website (and I will also be a user, and one of the three administrators of the website) - it's being built for a club I'm in.

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  • Should tests be in the same ruby file or in separeted ruby files?

    - by Junior Mayhé
    While using Selenium and Ruby to do some functional tests, I am worried with the performance. So is it better to add all test methods in the same ruby file, or I should put each one in separated code files? Below a sample with all tests in the same file: # encoding: utf-8 require "selenium-webdriver" require "test/unit" class Tests < Test::Unit::TestCase def setup @driver = Selenium::WebDriver.for :firefox @base_url = "http://mysite" @driver.manage.timeouts.implicit_wait = 30 @verification_errors = [] @wait = Selenium::WebDriver::Wait.new :timeout => 10 end def teardown @driver.quit assert_equal [], @verification_errors end def element_present?(how, what) @driver.find_element(how, what) true rescue Selenium::WebDriver::Error::NoSuchElementError false end def verify(&blk) yield rescue Test::Unit::AssertionFailedError => ex @verification_errors << ex end def test_1 @driver.get(@base_url + "/") # a huge test here end def test_2 @driver.get(@base_url + "/") # a huge test here end def test_3 @driver.get(@base_url + "/") # a huge test here end def test_4 @driver.get(@base_url + "/") # a huge test here end def test_5 @driver.get(@base_url + "/") # a huge test here end end

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  • If you had three months to learn one relatively new technology, which one would you choose?

    - by Ivo van der Wijk
    This question was taken from CodingHorror. On my list would be (and some actually are): Android Development (and possibly iPhone development) Go language and its concurrency NoSQL, specifically CouchDB RCTK, which happens to be my own idea / project (but all ideas have been thought or already, what matters is my implementation) But I don't think I'm being cutting-edge/thinking-outside-the-box here. What's on your list? Please don't restrict yourself to the list above - that's my list. I'm interested in hearing what others find interesting new technology.

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