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  • Approaches for generic, compile-time safe lazy-load methods

    - by Aaronaught
    Suppose I have created a wrapper class like the following: public class Foo : IFoo { private readonly IFoo innerFoo; public Foo(IFoo innerFoo) { this.innerFoo = innerFoo; } public int? Bar { get; set; } public int? Baz { get; set; } } The idea here is that the innerFoo might wrap data-access methods or something similarly expensive, and I only want its GetBar and GetBaz methods to be invoked once. So I want to create another wrapper around it, which will save the values obtained on the first run. It's simple enough to do this, of course: int IFoo.GetBar() { if ((Bar == null) && (innerFoo != null)) Bar = innerFoo.GetBar(); return Bar ?? 0; } int IFoo.GetBaz() { if ((Baz == null) && (innerFoo != null)) Baz = innerFoo.GetBaz(); return Baz ?? 0; } But it gets pretty repetitive if I'm doing this with 10 different properties and 30 different wrappers. So I figured, hey, let's make this generic: T LazyLoad<T>(ref T prop, Func<IFoo, T> loader) { if ((prop == null) && (innerFoo != null)) prop = loader(innerFoo); return prop; } Which almost gets me where I want, but not quite, because you can't ref an auto-property (or any property at all). In other words, I can't write this: int IFoo.GetBar() { return LazyLoad(ref Bar, f => f.GetBar()); // <--- Won't compile } Instead, I'd have to change Bar to have an explicit backing field and write explicit getters and setters. Which is fine, except for the fact that I end up writing even more redundant code than I was writing in the first place. Then I considered the possibility of using expression trees: T LazyLoad<T>(Expression<Func<T>> propExpr, Func<IFoo, T> loader) { var memberExpression = propExpr.Body as MemberExpression; if (memberExpression != null) { // Use Reflection to inspect/set the property } } This plays nice with refactoring - it'll work great if I do this: return LazyLoad(f => f.Bar, f => f.GetBar()); But it's not actually safe, because someone less clever (i.e. myself in 3 days from now when I inevitably forget how this is implemented internally) could decide to write this instead: return LazyLoad(f => 3, f => f.GetBar()); Which is either going to crash or result in unexpected/undefined behaviour, depending on how defensively I write the LazyLoad method. So I don't really like this approach either, because it leads to the possibility of runtime errors which would have been prevented in the first attempt. It also relies on Reflection, which feels a little dirty here, even though this code is admittedly not performance-sensitive. Now I could also decide to go all-out and use DynamicProxy to do method interception and not have to write any code, and in fact I already do this in some applications. But this code is residing in a core library which many other assemblies depend on, and it seems horribly wrong to be introducing this kind of complexity at such a low level. Separating the interceptor-based implementation from the IFoo interface by putting it into its own assembly doesn't really help; the fact is that this very class is still going to be used all over the place, must be used, so this isn't one of those problems that could be trivially solved with a little DI magic. The last option I've already thought of would be to have a method like: T LazyLoad<T>(Func<T> getter, Action<T> setter, Func<IFoo, T> loader) { ... } This option is very "meh" as well - it avoids Reflection but is still error-prone, and it doesn't really reduce the repetition that much. It's almost as bad as having to write explicit getters and setters for each property. Maybe I'm just being incredibly nit-picky, but this application is still in its early stages, and it's going to grow substantially over time, and I really want to keep the code squeaky-clean. Bottom line: I'm at an impasse, looking for other ideas. Question: Is there any way to clean up the lazy-loading code at the top, such that the implementation will: Guarantee compile-time safety, like the ref version; Actually reduce the amount of code repetition, like the Expression version; and Not take on any significant additional dependencies? In other words, is there a way to do this just using regular C# language features and possibly a few small helper classes? Or am I just going to have to accept that there's a trade-off here and strike one of the above requirements from the list?

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  • Embedding generic sql queries into c# program

    - by Pooja Balkundi
    Okay referring to my first question code in the main, I want the user to enter employee name at runtime and then i take this name which user has entered and compare it with the e_name of my emp table , if it exists i want to display all information of that employee , how can I achieve this ? using System; using System.Collections.Generic; using System.Linq; using System.Windows.Forms; using MySql.Data.MySqlClient; namespace ConnectCsharppToMySQL { public class DBConnect { private MySqlConnection connection; private string server; private string database; private string uid; private string password; string name; //Constructor public DBConnect() { Initialize(); } //Initialize values private void Initialize() { server = "localhost"; database = "test"; uid = "root"; password = ""; string connectionString; connectionString = "SERVER=" + server + ";" + "DATABASE=" + database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";"; connection = new MySqlConnection(connectionString); } //open connection to database private bool OpenConnection() { try { connection.Open(); return true; } catch (MySqlException ex) { //When handling errors, you can your application's response based //on the error number. //The two most common error numbers when connecting are as follows: //0: Cannot connect to server. //1045: Invalid user name and/or password. switch (ex.Number) { case 0: MessageBox.Show("Cannot connect to server. Contact administrator"); break; case 1045: MessageBox.Show("Invalid username/password, please try again"); break; } return false; } } //Close connection private bool CloseConnection() { try { connection.Close(); return true; } catch (MySqlException ex) { MessageBox.Show(ex.Message); return false; } } //Insert statement public void Insert() { string query = "INSERT INTO emp (e_name, age) VALUES('Pooja R', '21')"; //open connection if (this.OpenConnection() == true) { //create command and assign the query and connection from the constructor MySqlCommand cmd = new MySqlCommand(query, connection); //Execute command cmd.ExecuteNonQuery(); //close connection this.CloseConnection(); } } //Update statement public void Update() { string query = "UPDATE emp SET e_name='Peachy', age='22' WHERE e_name='Pooja R'"; //Open connection if (this.OpenConnection() == true) { //create mysql command MySqlCommand cmd = new MySqlCommand(); //Assign the query using CommandText cmd.CommandText = query; //Assign the connection using Connection cmd.Connection = connection; //Execute query cmd.ExecuteNonQuery(); //close connection this.CloseConnection(); } } //Select statement public List<string>[] Select() { string query = "SELECT * FROM emp where e_name=(/*I WANT USER ENTERED NAME TO GET INSERTED HERE*/)"; //Create a list to store the result List<string>[] list = new List<string>[3]; list[0] = new List<string>(); list[1] = new List<string>(); list[2] = new List<string>(); //Open connection if (this.OpenConnection() == true) { //Create Command MySqlCommand cmd = new MySqlCommand(query, connection); //Create a data reader and Execute the command MySqlDataReader dataReader = cmd.ExecuteReader(); //Read the data and store them in the list while (dataReader.Read()) { list[0].Add(dataReader["e_id"] + ""); list[1].Add(dataReader["e_name"] + ""); list[2].Add(dataReader["age"] + ""); } //close Data Reader dataReader.Close(); //close Connection this.CloseConnection(); //return list to be displayed return list; } else { return list; } } public static void Main(String[] args) { DBConnect db1 = new DBConnect(); Console.WriteLine("Initializing"); db1.Initialize(); Console.WriteLine("Search :"); Console.WriteLine("Enter the employee name"); db1.name = Console.ReadLine(); db1.Select(); Console.ReadLine(); } } }

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  • How to switch to a generic kernel in a headless Ubuntu Server 12.04?

    - by chmike
    I just got a dedicated server with Ubuntu 12.04 installed with a custom compiled kernel. Since I would like to install VirtualBox and this custom kernel doesn't support dynamic module loading (for security) I need to change the kernel. I'm running some Ubuntu servers for years but never palyed with grub and a headless computer. When the command update-grub is run it shows the different kernel it finds. Here is what I see Generating grub.cfg ... Found linux image: /boot/bzImage-3.2.13-xxxx-grs-ipv6-64 Found linux image: /boot/vmlinuz-3.2.0-34-generic Found initrd image: /boot/initrd.img-3.2.0-34-generic No volume groups found done The first one is the active one as seen with uname -r. To me it looks like the second kernel is the one I should use. But I don't know how to configure grub2 to use it. The computer is also configured with a software RAID using mdadm I guess. Never used that before. I don't know if playing with the grub of changing kernel could brake this. What must I do to set the generic kernel as the default one so that I can get VirtualBox running.

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  • How to prepare for a programming competition? Graphs, Stacks, Trees, oh my! [closed]

    - by Simucal
    Last semester I attended ACM's (Association for Computing Machinery) bi-annual programming competition at a local University. My University sent 2 teams of 3 people and we competed amongst other schools in the mid-west. We got our butts kicked. You are given a packet with about 11 problems (1 problem per page) and you have 4 hours to solve as many as you can. They'll run your program you submit against a set of data and your output must match theirs exactly. In fact, the judging is automated for the most part. In any case.. I went there fairly confident in my programming skills and I left there feeling drained and weak. It was a terribly humbling experience. In 4 hours my team of 3 people completed only one of the problems. The top team completed 4 of them and took 1st place. The problems they asked were like no problems I have ever had to answer before. I later learned that in order to solve them some of them effectively you have to use graphs/graph algorithms, trees, stacks. Some of them were simply "greedy" algo's. My question is, how can I better prepare for this semesters programming competition so I don't leave there feeling like a complete moron? What tips do you have for me to be able to answer these problems that involve graphs, trees, various "well known" algorithms? How can I easily identify the algorithm we should implement for a given problem? I have yet to take Algorithm Design in school so I just feel a little out of my element. Here are some examples of the questions asked at the competitions: ACM Problem Sets Update: Just wanted to update this since the latest competition is over. My team placed 1st for our small region (about 6-7 universities with between 1-5 teams each school) and ~15th for the midwest! So, it is a marked improvement over last years performance for sure. We also had no graduate students on our team and after reviewing the rules we found out that many teams had several! So, that would be a pretty big advantage in my own opinion. Problems this semester ranged from about 1-2 "easy" problems (ie bit manipulation, string manipulation) to hard (graph problems involving fairly complex math and network flow problems). We were able to solve 4 problems in our 5 hours. Just wanted to thank everyone for the resources they provided here, we used them for our weekly team practices and it definitely helped! Some quick tips that I have that aren't suggested below: When you are seated at your computer before the competition starts, quickly type out various data structures that you might need that you won't have access to in your languages libraries. I typed out a Graph data-structure complete with floyd-warshall and dijkstra's algorithm before the competition began. We ended up using it in our 2nd problem that we solved and this is the main reason why we solved this problem before anyone else in the midwest. We had it ready to go from the beginning. Similarly, type out the code to read in a file since this will be required for every problem. Save this answer "template" someplace so you can quickly copy/paste it to your IDE at the beginning of each problem. There are no rules on programming anything before the competition starts so get any boilerplate code out the way. We found it useful to have one person who is on permanent whiteboard duty. This is usually the person who is best at math and at working out solutions to get a head start on future problems you will be doing. One person is on permanent programming duty. Your fastest/most skilled "programmer" (most familiar with the language). This will save debugging time also. The last person has several roles between assessing the packet of problems for the next "easiest" problem, helping the person on the whiteboard work out solutions and helping the person programming work out bugs/issues. This person needs to be flexible and be able to switch between roles easily.

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  • I have made two template classes,could any one tell me if these things are useful?

    - by soul
    Recently i made two template classes,according to the book "Modern C++ design". I think these classes are useful but no one in my company agree with me,so could any one tell me if these things are useful? The first one is a parameter wrapper,it can package function paramters to a single dynamic object.It looks like TypeList in "Modern C++ design". You can use it like this: some place of your code: int i = 7; bool b = true; double d = 3.3; CParam *p1 = CreateParam(b,i); CParam *p2 = CreateParam(i,b,d); other place of your code: int i = 0; bool b = false; double d = 0.0; GetParam(p1,b,i); GetParam(p2,i,b,d); The second one is a generic callback wrapper,it has some special point compare to other wrappers: 1.This template class has a dynamic base class,which let you use a single type object represent all wrapper objects. 2.It can wrap the callback together with it's parameters,you can excute the callback sometimes later with the parameters. You can use it like this: somewhere of your code: void Test1(int i) { } void Test2(bool b,int i) { } CallbackFunc * p1 = CreateCallback(Test1,3); CallbackFunc * p2 = CreateCallback(Test2,false,99); otherwhere of your code: p1->Excute(); p2->Excute(); Here is a part of the codes: parameter wrapper: class NullType; struct CParam { virtual ~CParam(){} }; template<class T1,class T2> struct CParam2 : public CParam { CParam2(T1 &t1,T2 &t2):v1(t1),v2(t2){} CParam2(){} T1 v1; T2 v2; }; template<class T1> struct CParam2<T1,NullType> : public CParam { CParam2(T1 &t1):v1(t1){} CParam2(){} T1 v1; }; template<class T1> CParam * CreateParam(T1 t1) { return (new CParam2<T1,NullType>(t1)); } template<class T1,class T2> CParam * CreateParam(T1 t1,T2 t2) { return (new CParam2<T1,T2>(t1,t2)); } template<class T1,class T2,class T3> CParam * CreateParam(T1 t1,T2 t2,T3 t3) { CParam2<T2,T3> t(t2,t3); return new CParam2<T1,CParam2<T2,T3> >(t1,t); } template<class T1> void GetParam(CParam *p,T1 &t1) { PARAM1(T1)* p2 = dynamic_cast<CParam2<T1,NullType>*>(p); t1 = p2->v1; } callback wrapper: #define PARAM1(T1) CParam2<T1,NullType> #define PARAM2(T1,T2) CParam2<T1,T2> #define PARAM3(T1,T2,T3) CParam2<T1,CParam2<T2,T3> > class CallbackFunc { public: virtual ~CallbackFunc(){} virtual void Excute(void){} }; template<class T> class CallbackFunc2 : public CallbackFunc { public: CallbackFunc2():m_b(false){} CallbackFunc2(T &t):m_t(t),m_b(true){} T m_t; bool m_b; }; template<class M,class T> class StaticCallbackFunc : public CallbackFunc2<T> { public: StaticCallbackFunc(M m):m_m(m){} StaticCallbackFunc(M m,T t):CallbackFunc2<T>(t),m_m(m){} virtual void Excute(void){assert(CallbackFunc2<T>::m_b);CallMethod(CallbackFunc2<T>::m_t);} private: template<class T1> void CallMethod(PARAM1(T1) &t){m_m(t.v1);} template<class T1,class T2> void CallMethod(PARAM2(T1,T2) &t){m_m(t.v1,t.v2);} template<class T1,class T2,class T3> void CallMethod(PARAM3(T1,T2,T3) &t){m_m(t.v1,t.v2.v1,t.v2.v2);} private: M m_m; }; template<class M> class StaticCallbackFunc<M,void> : public CallbackFunc { public: StaticCallbackFunc(M method):m_m(method){} virtual void Excute(void){m_m();} private: M m_m; }; template<class C,class M,class T> class MemberCallbackFunc : public CallbackFunc2<T> { public: MemberCallbackFunc(C *pC,M m):m_pC(pC),m_m(m){} MemberCallbackFunc(C *pC,M m,T t):CallbackFunc2<T>(t),m_pC(pC),m_m(m){} virtual void Excute(void){assert(CallbackFunc2<T>::m_b);CallMethod(CallbackFunc2<T>::m_t);} template<class T1> void CallMethod(PARAM1(T1) &t){(m_pC->*m_m)(t.v1);} template<class T1,class T2> void CallMethod(PARAM2(T1,T2) &t){(m_pC->*m_m)(t.v1,t.v2);} template<class T1,class T2,class T3> void CallMethod(PARAM3(T1,T2,T3) &t){(m_pC->*m_m)(t.v1,t.v2.v1,t.v2.v2);} private: C *m_pC; M m_m; }; template<class T1> CallbackFunc *CreateCallback(CallbackFunc *p,T1 t1) { CParam2<T1,NullType> t(t1); return new StaticCallbackFunc<CallbackFunc *,CParam2<T1,NullType> >(p,t); } template<class C,class T1> CallbackFunc *CreateCallback(C *pC,void(C::*pF)(T1),T1 t1) { CParam2<T1,NullType>t(t1); return new MemberCallbackFunc<C,void(C::*)(T1),CParam2<T1,NullType> >(pC,pF,t); } template<class T1> CParam2<T1,NullType> CreateCallbackParam(T1 t1) { return CParam2<T1,NullType>(t1); } template<class T1> void ExcuteCallback(CallbackFunc *p,T1 t1) { CallbackFunc2<CParam2<T1,NullType> > *p2 = dynamic_cast<CallbackFunc2<CParam2<T1,NullType> > *>(p); p2->m_t.v1 = t1; p2->m_b = true; p->Excute(); }

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  • Are there deprecated practices for multithread and multiprocessor programming that I should no longer use?

    - by DeveloperDon
    In the early days of FORTRAN and BASIC, essentially all programs were written with GOTO statements. The result was spaghetti code and the solution was structured programming. Similarly, pointers can have difficult to control characteristics in our programs. C++ started with plenty of pointers, but use of references are recommended. Libraries like STL can reduce some of our dependency. There are also idioms to create smart pointers that have better characteristics, and some version of C++ permit references and managed code. Programming practices like inheritance and polymorphism use a lot of pointers behind the scenes (just as for, while, do structured programming generates code filled with branch instructions). Languages like Java eliminate pointers and use garbage collection to manage dynamically allocated data instead of depending on programmers to match all their new and delete statements. In my reading, I have seen examples of multi-process and multi-thread programming that don't seem to use semaphores. Do they use the same thing with different names or do they have new ways of structuring protection of resources from concurrent use? For example, a specific example of a system for multithread programming with multicore processors is OpenMP. It represents a critical region as follows, without the use of semaphores, which seem not to be included in the environment. th_id = omp_get_thread_num(); #pragma omp critical { cout << "Hello World from thread " << th_id << '\n'; } This example is an excerpt from: http://en.wikipedia.org/wiki/OpenMP Alternatively, similar protection of threads from each other using semaphores with functions wait() and signal() might look like this: wait(sem); th_id = get_thread_num(); cout << "Hello World from thread " << th_id << '\n'; signal(sem); In this example, things are pretty simple, and just a simple review is enough to show the wait() and signal() calls are matched and even with a lot of concurrency, thread safety is provided. But other algorithms are more complicated and use multiple semaphores (both binary and counting) spread across multiple functions with complex conditions that can be called by many threads. The consequences of creating deadlock or failing to make things thread safe can be hard to manage. Do these systems like OpenMP eliminate the problems with semaphores? Do they move the problem somewhere else? How do I transform my favorite semaphore using algorithm to not use semaphores anymore?

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  • Why do old programming languages continue to be revised?

    - by SunAvatar
    This question is not, "Why do people still use old programming languages?" I understand that quite well. In fact the two programming languages I know best are C and Scheme, both of which date back to the 70s. Recently I was reading about the changes in C99 and C11 versus C89 (which seems to still be the most-used version of C in practice and the version I learned from K&R). Looking around, it seems like every programming language in heavy use gets a new specification at least once per decade or so. Even Fortran is still getting new revisions, despite the fact that most people using it are still using FORTRAN 77. Contrast this with the approach of, say, the typesetting system TeX. In 1989, with the release of TeX 3.0, Donald Knuth declared that TeX was feature-complete and future releases would contain only bug fixes. Even beyond this, he has stated that upon his death, "all remaining bugs will become features" and absolutely no further updates will be made. Others are free to fork TeX and have done so, but the resulting systems are renamed to indicate that they are different from the official TeX. This is not because Knuth thinks TeX is perfect, but because he understands the value of a stable, predictable system that will do the same thing in fifty years that it does now. Why do most programming language designers not follow the same principle? Of course, when a language is relatively new, it makes sense that it will go through a period of rapid change before settling down. And no one can really object to minor changes that don't do much more than codify existing pseudo-standards or correct unintended readings. But when a language still seems to need improvement after ten or twenty years, why not just fork it or start over, rather than try to change what is already in use? If some people really want to do object-oriented programming in Fortran, why not create "Objective Fortran" for that purpose, and leave Fortran itself alone? I suppose one could say that, regardless of future revisions, C89 is already a standard and nothing stops people from continuing to use it. This is sort of true, but connotations do have consequences. GCC will, in pedantic mode, warn about syntax that is either deprecated or has a subtly different meaning in C99, which means C89 programmers can't just totally ignore the new standard. So there must be some benefit in C99 that is sufficient to impose this overhead on everyone who uses the language. This is a real question, not an invitation to argue. Obviously I do have an opinion on this, but at the moment I'm just trying to understand why this isn't just how things are done already. I suppose the question is: What are the (real or perceived) advantages of updating a language standard, as opposed to creating a new language based on the old?

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  • Summer Programming Plans

    - by Gabe
    I've wanted to start "hacking" for many months now. But I put it off in favor of school and other things. Now, though, I'm free for the summer and want to learn as much as I can. I have a rough idea of what I want to try my hand at, but need some guidance as to what specifically - and how - I should learn. This is my plan so far: 1) Get good at programming in general. I plan to read up on how to think/work like a programmer. I'm waiting for the Pragmatic Programmer to arrive, which will be the first book I read. Q: What other books/ebooks should I look at? What more can I do here? 2) Learn/Improve at HTML/CSS. My first project will be to make a personal website/blog for myself using HTML and CSS. ----Then I hope to write/design articles like Dustin Curtis. After I finish this (and learn a programming language) I'll try to create user-based a user-focused website. Q: It's my understanding that just trying to design/manage websites is a good way to learn/improve at HTML/CSS. Is that all correct? 3) Try music development. This might be a sort of stretch for stackoverflow, but I'm interested in mixing/making techno songs. (Think Justice, or Daft Punk, or MSTRKRFT.) Q: I have a Mac. Any ideas on how I could start/learn music making? Any programs I should download, for instance? 4) My main goal: Learning a web development language/framework. I'm a year into learning/using C++. But what I really want to do is develop websites and web apps. I've searched online, and there seems to be great debate over which language/framework to learn first (and which is best). I think I've narrowed it down to three: Ruby (Rails), Python (Django), and PHP (?). Q #1: Which should I learn and use first? (Reasons?) Q #2: One reason I was leaning towards PHP is that I'm taking a PHP development course next semester. Learning it now would make that course easy. If PHP was not the answer to Q #1, is it worth learning both? Or, would it be better to just focus on PHP for this summer and next semester, and then transition thereafter to a better language? 5) iPhone/iPad Programming (Maybe). I've a number of simple, useful app ideas that I'd like to eventually get too. I just bought a Mac, as well as a few app development books. Q #1: Am I spreading myself thin trying to learn all of the above, and objective-C? Q #2: How much harder/easier is objective-C compared to the above languages? Also, how easy is it to learn obj-C after learning a web development language (and some C++)? Q #3: Yes or no? Should I go for it, or just keeep with #1-4 for now? Also: If you have any tips on how I should learn (or how you learned to hack), I'm all ears. I'd be especially interested in how you planned out learning: did you just hack whenever you felt like it, or did you "study" the language a few hours a day, or something else? Thanks so much, guys.

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  • Primary language - C++/Qt, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Primary language - QtC++, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Any task-control algorithms programming practices?

    - by NumberFour
    Hi, I was just wondering if there's any field which concerns the task-control programming (or at least that's the way I call it). For a better explanation of task-control consider the following scenario: An application (master-thread) waits for a command - which might be a particular action or a set of actions the application should perform. When a command is received the master-thread creates a task (= spawns an independent thread which actually does the action) and adds a record in it's task-list - thus keeping track of the time of execution, thread handle, task priority...etc. The master-thread awaits for any other incoming commands while taking care of all the tasks - e.g: kills tasks running too long, prioritizes tasks with higher priorities, kills a task on a request of another task, limits the number of currently running tasks, allows task scheduling, cleans finished tasks (threads) and so on. The model is pretty similar to what we can see in OS dealing with running processes. Are there any good practices programming such task-models or is there some theoretical work done in this field? Maybe my question is too generalized, but at least I wanted to know whether there are any experiences working on such models or if there's a better approach. Thanks for any answers.

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  • General Web Programming/designing Question: ?

    - by Prasad
    hi, I have been in web programming for 2 years (Self taught - a biology researcher by profession). I designed a small wiki with needed functionalities and a scientific RTE - ofcourse lot is expected. I used mootools framework and AJAX extensively. I was always curious when ever I saw the query strings passed from URL. Long encrypted query string directly getting passed to the server. Especially Google's design is such. I think this is the start of providing a Web Service to a client - I guess. Now, my question is : is this a special, highly professional, efficient / advanced web design technique to communicate queries via the URL ? I always felt that direct URL based communication is faster. I tried my bit and could send a query through the URL directly. here is the link: http://sgwiki.sdsc.edu/getSGMPage.php?8 By this , the client can directly link to the desired page instead of searching and / or can automate. There are many possibilities. The next request: Can I be pointed to such technique of web programming? oops: I am sorry, If I have not been able to convey my request clearly. Prasad.

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  • Best cubicle toys for programming

    - by dlamblin
    I need some employee/co-worker Christmas gift ideas. Do you have any good cubicle toys that help you to do any of: think about programming problems solve programming problems by representing common abstractions can be directly programmed can interface with a PC based IDE to be programmed. it may present problems that can be solved, to kick start problem solving. Disallowed items are: reference material in book, pamphlet, poster or cheat-sheet form, even if it has kick ass pop-cultural references. edibles. [discuss separately] things that need their own lab-space and/or extensive tools to be worked with. So yes, Lego Mindstorms come to mind, but they aren't cubicle toys because they cost more than cubicle toys would, and they have too many losable parts. comments on the answers so far: The 20 Questions game sounds quite neat as it could get you thinking; The bean balls could be used as tokens in a problem, so I can see that working. The magnetic toys like ball of whacks or the ball-and-stick ones present hands on fun of a structural nature... now can there be a similar hands on fun toy that aids in representing a solution to a problem? The Gui Mags clearly could, but they're quite utility oriented. The AVR Butterfly is less of a toy but definitely priced attractively, cheaper and more responsive than a basic stamp. I'm not going to pick an answer; there's several great suggestions here. Thank you.

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  • How do people know so much about programming?

    - by Luciano
    I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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  • Programming Technique: How to create a simple card game

    - by Shyam
    Hi, As I am learning the Ruby language, I am getting closer to actual programming. So I was thinking of creating a simple card game. My question isn't Ruby orientated, but I do know want to learn how to solve this problem with a genuine OOP approach. In my card game I want to have four players. Using a standard deck with 52 cards, no jokers/wildcards. In the game I won't use the Ace as a dual card, it is always the highest card. So, the programming problems I wonder about are the following: How can I sort/randomize the deck of cards? There are four types, each having 13 values. Eventually there can be only unique values, so picking random values could generate duplicates. How can I implement a simple AI? As there are tons of card games, someone would have figured this part out already, so references would be great. I am a truly Ruby nuby, and my goal here is to learn to solve problems, so pseudo code would be great, just to understand how to solve the problem programmatically. I apologize for my grammar and writing style if it's unclear, for it is not my native language. Also pointers to sites where such challenges are explained, would be a great resource! Thank you for your comments, answers and feedback!

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  • c# web extracting programming, which libraries, examples samples please

    - by user287745
    I have just started programming and have made a few small applications in C and C#. My understanding is that programming for web and thing related to web is nowadays a very easy task. Please note this is for personnel learning, not for rent a coder or any money making. An application which can run on any Windows platform even Windows 98. The application should start automatically at a scheduled time and do the following. Connect to a site which displays stock prices summary (high low current open). Capture the data (excluding the other things in the site.) And save it to disk (an SQL database) Please note:- Internet connection is assumed to be there always. Do not want to know how to make database schema or database. The stock exchange has no law prohibiting the use of the data provided on its site, but I do not want to mention the name in case I am wrong, but it's for personal private use only. The data of summary of pricing is arranged in a table such that when copied pasted to MS Excel it automatically forms a table. need steps guidance please, examples, lbraries

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  • How do I get an overview and a methodology for programming in Python

    - by Peter Nielsen
    I've started to learn Python and programming from scratch. I have not programmed before so it's a new experience. I do seem to grasp most of the concepts, from variables to definitions and modules. I still need to learn a lot more about what the different libraries and modules do and also I lack knowledge on OOP and classes in Python. I see people who just program in Python like that's all they have ever done and I am still just coming to grips with it. Is there a way, some tools, a logical methodology that would give me an overview or a good hold of how to handle programming problems ? For instance, I'm trying to create a parser which we need at the office . I also need to create a spider that would collect links from various websites. Is there a formidable way of studying the various modules to see what is needed ? Or is it just nose to the grind stone and understand what the documentation says ? Sorry for the lengthy question..

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  • An Ideal Keyboard Layout for Programming

    - by Jon Purdy
    I often hear complaints that programming languages that make heavy use of symbols for brevity, most notably C and C++ (I'm not going to touch APL), are difficult to type because they require frequent use of the shift key. A year or two ago, I got tired of it myself, downloaded Microsoft's Keyboard Layout Creator, made a few changes to my layout, and have not once looked back. The speed difference is astounding; with these few simple changes I am able to type C++ code around 30% faster, depending of course on how hairy it is; best of all, my typing speed in ordinary running text is not compromised. My questions are these: what alternate keyboard layouts have existed for programming, which have gained popularity, are any of them still in modern use, do you personally use any altered layout, and how can my layout be further optimised? I made the following changes to a standard QWERTY layout. (I don't use Dvorak, but there is a programmer Dvorak layout worth mentioning.) Swap numbers with symbols in the top row, because long or repeated literal numbers are typically replaced with named constants; Swap backquote with tilde, because backquotes are rare in many languages but destructors are common in C++; Swap minus with underscore, because underscores are common in identifiers; Swap curly braces with square brackets, because blocks are more common than subscripts; and Swap double quote with single quote, because strings are more common than character literals. I suspect this last is probably going to be the most controversial, as it interferes the most with running text by requiring use of shift to type common contractions. This layout has significantly increased my typing speed in C++, C, Java, and Perl, and somewhat increased it in LISP and Python.

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  • What programming language is this?

    - by Richard M.
    I recently stumbled over a very odd source listing on a rather old programming-related site (lost it somewhere in my browser history as I didn't care about it at first). I think that this is part of a simple (console-based?) snake game. I searched and searched but didn't find a language that looked somwhat like this. This seems like a mix of Python, Ruby and C++. What the hell? What programming-language is the below source listing written in? Maybe you can figure it out? my Snake.hasProps { length parts xDir yDir } & hasMethods { init: length = 0 parts[0].x,y = 5 move: parts[ 0 ].x,y.!add xDir | yDir # Move the head map parts(i,v): parts[ i ] = parts[ i + 1 ] checkBiteSelf checkFeed checkBiteSelf: part } my SnakePart.hasProps { x y } fork SnakePart to !Feed my Game.hasProps { frameTime = 30 } & hasMethods { init: mainloop mainloop: sys.util.sleep frameTime Snake.move Field.getInput -> Snake.xDir | Snake.yDir Field.reDraw with Snake & Feed & Game # For FPS } main.isMethod { game.init }

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  • Non-english domain naming issues in programming

    - by Svend
    Most programming code, I imagine is written in english. But I'm curious how people handling the issue of naming herein. Alot of programming is done within some bussiness domain, usually with well established terms for certain procedures, items. I'm from Denmark for instance, and something I work alot with has a term called "indblikskode", which sorta translates to "insight code". So, do I use the line "string indblikskode = ..." in the C# code for some webservice related to this? Or do I try to use a translation, such as "insightcode"? The bussiness I'm in isn't even consistent in it's language, for instance using the term "organisatorisk enhed" (organizatorical unit), but just as often using the abbreviation "OU", which is obviously abbreviated from the english. How do other people handle this naming issue, while keeping consistent, and sane (in everything from simple variable names in your code, to database tables, to server names)? Duplicates: Should identifiers and comments be always in English or in the native language of the application and developers? Do you use another language instead of english ?

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  • Need an Overview of Possibilities for multicolumn programming

    - by Sam
    Hi folks, From source1 and source2 i gather that IE9 will NOT support multi-column css3!! Since it is still the most popular browser (another thing i cannot understand), i am left but no other choice than to use Programming Power to make multi-columns work. Now, I use three divs that float to left, and which are manually filled with text. Please don't laugh i know its stupid! But I would wish to not to have to worry about the columns and just have a one piece of (un-interrupted) text which all goes into only 1 div, and then have a program smart enough to split it up into X equally wide columns. Question: before i start reinvent the wheel, what methods of programming power have you known that tackle this elegantly? Please suggest your best working multi-column layout sources so I can evaluate which option is the best (I will update the below table). Exploring all possibilities 2011 and further, to enable multi column text user experience: Language Author SourceCodeUsage WorksOnAllMajorBrowser? ================================================================================= html manual labour put text manually in separate left-floating divs "Y" // Upside: control! Downside: few changes necessitates to reflow 3 divs manually! CSS3 w3c css3.info/preview/multi-column-layout/ "N" // {-moz-column-count: 3; -webkit-column-count: 3; } Thats all! javascript a list apart will add url soon ? // php ? ? ? //

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  • Three most critical programming concepts

    - by Todd
    I know this has probably been asked in one form or fashion but I wanted to pose it once again within the context of my situation (and probably others here @ SO). I made a career change to Software Engineering some time ago without having an undergrad or grad degree in CS. I've supplemented my undergrad and grad studies in business with programming courses (VB, Java,C, C#) but never performed academic coursework in the other related disciplines (algorithms, design patterns, discrete math, etc.)...just mostly self-study. I know there are several of you who have either performed interviews and/or made hiring decisions. Given recent trends in demand, what would you say are the three most essential Comp Sci concepts that a developer should have a solid grasp of outside of language syntax? For example, I've seen blog posts of the "Absolute minimum X that every programmer must know" variety...that's what I'm looking for. Again if it's truly a redundancy please feel free to close; my feelings won't be hurt. (Closest ones I could find were http://stackoverflow.com/questions/164048/basic-programming-algorithmic-concepts- which was geared towards a true beginner, and http://stackoverflow.com/questions/648595/essential-areas-of-knowledge-which I didn't feel was concrete enough). Thanks in advance all! T.

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  • Begin game programming basics

    - by AJ
    My 14 year old kid brother wants to learn to program games. He has never programmed but would like to learn programming. His interest lies with games and game programming and he understands that it can be difficult but he wants to do that. So, obviously, I turned to SO folks to know what you feel on how he should go about it. Remember, please suggest on Areas that beginners can choose, how to begin in that area, what to read in the beginning, initial languages in the beginning etc. Once the beginning part is taken care of, you may also suggest the intermediate and advanced stuff but this question is about very beginning level. If there are areas like Web games Vs. console games Vs generic computer games, then please advice on the areas. As I said he has never programmed, he might want to try all the areas and choose the one he likes the best. I hope this is not too much to ask for someone who is in this field but if this question is huge, please advice on how to break it into multiple questions. ~Thanks.

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