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  • 'is instanceof' Interface bad design

    - by peterRit
    Say I have a class A class A { Z source; } Now, the context tells me that 'Z' can be an instance of different classes (say, B and C) which doesn't share any common class in their inheritance tree. I guess the naive approach is to make 'Z' an Interface class, and make classes B and C implement it. But something still doesn't convince me because every time an instance of class A is used, I need to know the type of 'source'. So all finishes in multiple 'ifs' making 'is instanceof' which doesn't sound quite nice. Maybe in the future some other class implements Z, and having hardcoded 'ifs' of this type definitely could break something. The escence of the problem is that I cannot resolve the issue by adding functions to Z, because the work done in each instance type of Z is different. I hope someone can give me and advice, maybe about some useful design pattern. Thanks

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  • In MS Access is there a way to allow forms to update while maintaning Read Only

    - by Alex
    I have several forms linked tables via queries. The form pull data such as sales and ratios by selecting a product from the main's form's combo box. I am however having to issues: 1- I would ultimately prefer the combo box to be a free entry; however by just entering in the box and hitting enter (not a button called “enter on a screen” which would initiate recalcs, just normal enter), while it does bring the new information in sub-forms it also changes the information in the original table. If I make the table read only that it just doesn't allow the form to work by saying that the table is read only. 2- The same Read only issue occurs when another user with read only rights tries to use the database. I understand that ready only is functioning as intended, however I am wondering if there is way to make some functions work while disallowing the updating. I am unfortunately learning on the go, so go easy plz. Thank you

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  • How does compiler use lib file ?

    - by Xinus
    I am curious about how c/c++ compiler analyse lib files ? I mean say I create a library containing some classes, I am using that library in my main program. How does compiler know what class names are there in that library. Of course that information is present in binary format, I want to use that functionality in my program, to be specific I have a binary lib file and I want to know all classes and properties/functions present in that lib file. Is it possible ? If compiler can do that why can't some library ? thanks for any clue

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  • how to link static library into dynamic library in gcc

    - by bob
    Under gcc (g++), I have compiled a static .a (call it some_static_lib.a) library. I want to link (is that the right phrase?) this .a file into another dynamic library (call it libsomeDyn.so) that I'm building. Though the .so compiles, I don't see content of .a under .so using nm command: /usr/bin/g++ -fPIC -g -O2 -Wall -Werror -pipe -march=pentium3 -mtune=prescott -MD -D_FILE_OFFSET_BITS=64 -DLINUX -D_GNU_SOURCE -D_THREAD_SAFE -DUSE_STD_YUTSTRING -DNO_FACTORY -I../../../../../../../../ -I../../../../../../../..//libraries -Wl,-rpath,/usr/lib -o libsomeDyn.so some.o another.o some_static_lib.a -shared -Wl -x -Wl,-soname,libsomeDyn.so I do not see functions under some_static_lib.a under libsomeDyn.so. What am I doing wrong?

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  • R: how to make a unique set of names from a vector of strings?

    - by Mike Dewar
    Hi, I have a vector of strings. Check out my vector, it's awesome: > awesome [1] "a" "b" "c" "d" "d" "e" "f" "f" I'd like to make a new vector that is the same length as awesome but where, if necessary, the strings have been uniqueified. For example, a valid output of my desired function would be > awesome.uniqueified [1] "a" "b" "c" "d.1" "d.2" "e" "f.1" "f.2" Is there an easy, R-thonic and beautiful way to do this? I should say my list in real life (it's not called awesome) contains 25000ish mircoarray probeset identifiers. I'm always nervous when I embark on writing little generic functions (which I'm sure I could do) as I'm sure some R guru has come across this problem in the past, nailed it with some incredible algorithm that doesn't even have to store more than half an element in the vector. I'm just not sure what they might have called it. Probably not uniqueify.

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  • What's the best way to call jQuery scripts, in HTML/PHP template, or seperate js file?

    - by j-man86
    StackOverflow is telling me this is a subjective question, but I think it's a matter of fact! I have a number of scripts that I'm using on different parts of my site. In terms of making fewer http requests, I know it's better to combine all of these scripts into one .js file. However, isn't a waste of time for a page to call a .js full of 10 or 15 different functions when it's only using one? The other method I am using is to use PHP conditional statements... <?php if( is_page() ) { > $(document).ready(function(){ ... }); <?php } ?> What's the best method or comination of these methods?

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  • Why is the 'this' keyword not a reference type in C++ [closed]

    - by Dave Tapley
    Possible Duplicates: Why ‘this’ is a pointer and not a reference? SAFE Pointer to a pointer (well reference to a reference) in C# The this keyword in C++ gets a pointer to the object I currently am. My question is why is the type of this a pointer type and not a reference type. Are there any conditions under which the this keyword would be NULL? My immediate thought would be in a static function, but Visual C++ at least is smart enough to spot this and report static member functions do not have 'this' pointers. Is this in the standard?

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  • Simple wrapping of C code with cython

    - by Jose
    Hi, I have a number of C functions, and I would like to call them from python. cython seems to be the way to go, but I can't really find an example of how exactly this is done. My C function looks like this: void calculate_daily ( char *db_name, int grid_id, int year, double *dtmp, double *dtmn, double *dtmx, double *dprec, double *ddtr, double *dayl, double *dpet, double *dpar ) ; All I want to do is to specify the first three parameters (a string and two integers), and recover 8 numpy arrays (or python lists. All the double arrays have N elements). My code assumes that the pointers are pointing to an already allocated chunk of memory. Also, the produced C code ought to link to some external libraries.

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  • What to return as an iterator when there is no container?

    - by DaClown
    I have an inheritance structure of objects with begin() and end() as pure virtual member functions in the base class. From this objects I'm planning to build a composite structure. This inner objects have std::vector member the begin() and end() get their data from. But in a leaf class there is no vector. Now I try to find a return value for begin() and end() in the leaf classes. What would be a good way to do that? The easiest way would be to have a vector member in the leaf classes with no elements in it to fuel begin() and end(), but this just doesn't feel right.

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  • Java escape HTML - string replace slow?

    - by cpf
    Hi StackOverflow, I have a Java application that makes heavy use of a large file, to read, process and give through to SolrEmbeddedServer (http://lucene.apache.org/solr/). One of the functions does basic HTML escaping: private String htmlEscape(String input) { return input.replace("&", "&amp;").replace(">", "&gt;").replace("<", "&lt;") .replace("'", "&apos;").replaceAll("\"", "&quot;"); } While profiling the application, the program spends roughly 58% of the time in this function, a total of 47% in replace, and 11% in replaceAll. Now, is the Java replace that slow, or am I on the right path and should I consider the program efficient enough to have its bottleneck in Java and not in my code? (Or am I replacing wrong?) Thanks in advance!

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  • Visual Studio 2010 element names for theming

    - by Anthony Potts
    I am trying to figure out what the element name for the tooltip is in Visual studio so that I can change the style using the extension found here. Anyone know what that is? I am using the default theme which seems to have a white to light grey gradient on it. This is less than optimal since the text for the functions are also white. In a more general question (and perhaps better), is there anything that maps the names as they are found in the theme to where they are in the IDE.

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  • How often do you implement the big three?

    - by Neil Butterworth
    I was just musing about the number of questions here that either are about the "big three" (copy constructor, assignment operator and destructor) or about problems caused by them not being implemented correctly, when it occurred to me that I could not remember the last time I had implemented them myself. A swift grep on my two most active projects indicate that I implement all three in only one class out of about 150. That's not to say I don't implement/declare one or more of them - obviously base classes need a virtual destructor, and a large number of my classes forbid copying using the private copy ctor & assignment op idiom. But fully implemented, there is this single lonely class, which does some reference counting. So I was wondering am I unusual in this? How often do you implement all three of these functions? Is there any pattern to the classes where you do implement them?

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  • program crashes at CIN input | C++

    - by TimothyTech
    hello okay, so i made a DOS program however my game always crashes on my second time running to the cin function. #include <iostream> #include <string> #include <ctime> #include <cstdlib> using namespace std; //call functions int create_enemyHP (int a); int create_enemyAtk (int a); int find_Enemy(int a); int create_enemyDef (int a); // user information int userHP = 100; int userAtk = 10; int userDef = 5; string userName; //enemy Information int enemyHP; int enemyAtk; int enemyDef; string enemies[] = {"Raider", "Bandit", "Mugger"}; int sizeOfEnemies = sizeof(enemies) / sizeof(int); string currentEnemy; int chooseEnemy; // ACTIONS int journey; int test; int main() { // main menu cout << "welcome brave knight, what is your name? " ; cin >> userName; cout << "welcome " << userName << " to Darland" << endl; //TRAVELING MENU: cout << "where would you like to travel? " << endl; cout << endl << " 1.> Theives Pass " << endl; cout << " 2.> Humble Town " << endl; cout << " 3.> Mission HQ " << endl; cin >> journey; if (journey == 1) { // action variable; string c_action; cout << "beware your journey grows dangerous " << endl; //begins battle // Creating the enemy, HP ATK DEF AND TYPE. ; srand(time(0)); enemyHP = create_enemyHP(userHP); enemyAtk = create_enemyAtk(userAtk); enemyDef = create_enemyDef(userDef); chooseEnemy = find_Enemy(sizeOfEnemies); currentEnemy = enemies[chooseEnemy]; cout << " Here comes a " << currentEnemy << endl; cout << "stats: " << endl; cout << "HP :" << enemyHP << endl; cout << "Attack : " << enemyAtk << endl; cout << "Defense : " << enemyDef << endl; ACTIONS: cout << "Attack <A> | Defend <D> | Items <I>"; cin >> c_action; //if ATTACK/DEFEND/ITEMS choice if (c_action == "A" || c_action == "a"){ enemyHP = enemyHP - userAtk; cout << " you attack the enemy reducing his health to " << enemyHP << endl; userHP = userHP - enemyAtk; cout << "however he lashes back causing you to have " << userHP << "health left " << endl; //end of ATTACK ACTION } the last line "cin c_action crashes. i use two other pages. they just create the functions. is it a complier issue. also why does my complier always shutdown after it runs he app. is there a way to stop it?

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  • Low FPS in some games, but hardware not fully used

    - by Mario De Schaepmeester
    I just did a little funny experiment in the game/sim "Train Simulator 2013". I normally have good FPS in it (around 30) at full settings. What I did was make a really, really long train so that the calculations the sim needed to make were enormous (the sim is quite realistic, it takes all things into account like speed/acceleration, G-forces, comfort levels, possible wheel slip and many more, and most of those things on each carriage seperately). This resulted in only 14FPS as reported by the game, but it felt more like 8FPS or so. I have a Logitech G15 keyboard which has an LCD, and it allows me to monitor CPU/RAM and video card load on it. The strange thing is, all CPU cores were busy, but the total load was only about 60% maximum at all times. The video card was only on 30% load (possibly an important note, the memory was full, which is however not unusual for the game in question). The RAM had plenty of room and there weren't many operations as it didn't grow or shrink much. I just have the feeling that the game would run smoother if it used more of my hardware power. Why is it not doing so? I had the same in another game, The Elder Scrolls: Morrowind when using more than 100 mods (that all use scripting) and a few high res texture mods, + a full-on graphics improvement program. The engine is very old (2003), and so I thought this might be the cause (not being optimised for multithreading). I had thought of possible causes, like: The operating system doesn't let the games use all the resources. It doesn't make use of multi-threading appropriately. To eliminate the former, I tried a CPU stress tool and that got 100% CPU juice as I let it run, so the OS is not the problem. I gave its thread the "higher" priority though. My actual question In both games, I did things the engine was not really built to do or support. Can those games' framerate be limited cause of their own engine not being able to cope? What is the real reason and more importantly, can I help it? And in any case, could something actually be wrong with my hardware? It's all reasonably new, a couple of months, and I (almost) never experience any other trouble. Modern and much more demanding games work absolutely fine. Specs CPU: AMD Phenom II 965 X4 @ 3.4gHz RAM: 8GB of DDR3 RAM Video: MSI GTX560 (nVidia chip) with 1GB of GDDR5 memory OS: Windows 7 Ultimate 64 bit Nothing overclocked.

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  • removing dependancy of a private function inside a public function using Rhino Mocks

    - by L G
    Hi All, I am new to mocking, and have started with Rhino Mocks. My scenario is like this..in my class library i have a public function and inside it i have a private function call, which gets output from a service.I want to remove the private function dependency. public class Employee { public virtual string GetFullName(string firstName, string lastName) { string middleName = GetMiddleName(); return string.Format("{0} {2} {1}", firstName, lastName,middleName ); } private virtual string GetMiddleName() { // Some call to Service return "George"; } } This is not my real scenario though, i just wanted to know how to remove dependency of GetMiddleName() function and i need to return some default value while unit testing. Note : I won't be able to change the private function here..or include Interface..Keeping the functions as such, is there any way to mock this.Thank

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  • How to correctly hook and return GetDlgItemTextA from C++ to C# to C++ from EasyHook

    - by Gbps
    I'm using EasyHook, a C# library for injecting and detouring functions from unmanaged applications. I'm trying to hook onto GetDlgItemTextA, which takes the arguments: UINT WINAPI GetDlgItemText( __in HWND hDlg, __in int nIDDlgItem, __out LPTSTR lpString, __in int nMaxCount );` In my hook, I am casting it as: [DllImport("user32.dll", // CharSet = CharSet.Unicode, SetLastError = true, CallingConvention = CallingConvention.StdCall)] static extern uint GetDlgItemTextA(IntPtr hWin, int nIDDlgItem, StringBuilder text, int MaxCount); And my hook is: static uint DGetDlgItemText_Hooked(IntPtr hWin, int nIDDlgItem, StringBuilder text, int MaxCount) { // call original API... uint ret = GetDlgItemTextA(hWin, nIDDlgItem, text, MaxCount); MessageBox.Show(text.ToString()); return ret; } Unfortunately, the moment this is called, the hooked application crashes. Is there a better cast I can use to successfully hook onto this function? Thanks! I've compiled, editted, and confirmed the working condition of my EasyHook setup. This is just casing and hooking only.

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  • How to maintain fixed size of C variable types over different machines?

    - by Alex
    I've all this kind of functions. ssize_t fuc1(int var1, void *buf, size_t count); int func2(char *charPtr, int mode, int dev); short func3( long var2); problem is that data types in C has different sizes when compiled on different machines(64bit & 32bit). This is true for even void*. For some reasons. I need to ensure that these sizes all are same on every machine(64bit & 32bit). So, how should I modify these ?

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  • Adapting methods which return true/false

    - by James P.
    What's the best practise when adapting C-style functions which return a true/false to Java? Here's a simple method to illustrate where the problem lies. public static boolean fileNameEndsWithExtension( String filename, String fileExtension) { return filename.endsWith( fileExtension ); } Note that there's probably a more elegant way of filtering files (feel free to comment on this). Anyway, if filename is a null value, does one: Return a false if filename is null? If so, how does one go about distinguishing between the case where filename is null and the case where the String or file name doesn't end with a given file extension? Change the return type to the wrapper class Boolean which allows a null value. Throw an Exception and force the programmer to make sure that a null value is never passed to the method? Use another solution?

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  • Ways to optimize Android App code based on function call stack?

    - by K-RAN
    I've been told that Android OS stores all function calls in a stack. This can lead to many problems and cause the 'hiccups' during runtime, even if a program is functionalized properly, correct? So the question is, how can we prevent this from happening? The obvious solution is to functionalize less, along with other sensible acts such as refraining from excessively/needlessly creating objects, performing static calls to functions that don't access fields, etc... Is there another way though? Or can this only be done through careful code writing on the programmers' part? Does the JVM/JIT automatically optimize the bytecode during compile time to account for this?? Thanks a lot for your responses!!

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  • F# powerpack and distribution

    - by rwallace
    I need arbitrary precision rational numbers, which I'm given to understand are available in the F# powerpack. My question is about the mechanics of distribution; my program needs to be able to compile and run both on Windows/.Net and Linux/Mono at least, since I have potential users on both platforms. As I understand it, the best procedure is: Download the powerpack .zip, not the installer. Copy the DLL into my program directory. Copy the accompanying license file into my program directory, to make sure everything is above board. Declare references and go ahead and use the functions I need. Ship the above files along with my source and binary, and since the DLL uses byte code, it will work fine on any platform. Is this the correct procedure? Am I missing anything?

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  • What is the best way to organize Java code since you can't pass by reference?

    - by Adam
    I'm learning how to code in Java after after coming from C. In C I always separated everything into individual functions to make the code easier to follow and edit. I was trying to do this in java but now since I realized that you can't use pointers, I am a bit confused as to what the best way to do this is. So for example I want to have a method that creates four alerts for me. So I pass it an alert builder that can then create the alerts. I can return them in an array, but in my code I already have the alerts individually named, and I would like to keep it that way so I wouldn't need to refer to them as alert[1], alert[2]... etc. So that means I would have to rename them, which would add additional code which would probably be longer than the code in the actual method! Am I thinking about this the right way? Is there anything I can do?

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  • F# replace ref variable with something fun

    - by Stephen Swensen
    I have the following F# functions which makes use of a ref variable to seed and keep track of a running total, something tells me this isn't in the spirit of fp or even particular clear on its own. I'd like some direction on the clearest (possible fp, but if an imperative approach is clearer I'd be open to that) way to express this in F#. Note that selectItem implements a random weighted selection algorithm. type WeightedItem(id: int, weight: int) = member self.id = id member self.weight = weight let selectItem (items: WeightedItem list) (rand:System.Random) = let totalWeight = List.sumBy (fun (item: WeightedItem) -> item.weight) items let selection = rand.Next(totalWeight) + 1 let runningWeight = ref 0 List.find (fun (item: WeightedItem) -> runningWeight := !runningWeight + item.weight !runningWeight >= selection) items let items = [new WeightedItem(1,100); new WeightedItem(2,50); new WeightedItem(3,25)] let selection = selectItem items (new System.Random())

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  • MacOSX: OSAtomic vs OSAtomicBarrier

    - by anon
    For the functions here: #include <libkern/OSAtomic.h> there are OSAtomic and OSAtomicBarrier versions. However, the documentation does not show sample code for: When is it safe to use just OSAtomic, without the OSAtomicBarrier version When is it that OSAtomic would be unsafe, but OSAtomiBarrier would be safe. Can anyone provide explainations + sample codes? [Random ramblings of "your opinion" without actual code is useless. Readers: please down vote such answers; and vigrously upvote answers with actual code.] [C/C++ code preferred; Assembly okay too.]

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  • How to make schema and code dynamic?

    - by Jonarch
    I want to make my database schema and application code as dynamic as possible to handle "unknown" use cases and changes. Developing in PHP and MySQL. Twice now I have had to change my entire schema including table and column names and this means the developers have to go back to the application code and modify all the SQL queries and table/columns names. So to prevent this I want to if just like we do on pages where we have page content, title bar etc dynamic like a %variable%, can we do it for the schema and maybe even for the php code functions and classes somehow? It takes weeks to re-do all changes like this vs if it is dynamic it can be done in under a day.

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  • Parsing plain data with Javascript (JQuery)

    - by Angelus
    Well , I have this text in a Javascript Var: GIMP Palette Name: Named Colors Columns: 16 # 255 250 250 snow (255 250 250) 248 248 255 ghost white (248 248 255) 245 245 245 white smoke (245 245 245) 220 220 220 gainsboro (220 220 220) 255 250 240 floral white (255 250 240) 253 245 230 old lace (253 245 230) 250 240 230 linen (250 240 230) 250 235 215 antique white (250 235 215) 255 239 213 papaya whip (255 239 213) And What I need is to cut it in lines and put them in one Array , after that i must separate each number and the rest in an string. I'm getting crazy searching functions to do that but now i can't see anyone in Javascript. modified End expected format will be first the next: array[0]='255 250 250 snow (255 250 250)' Then i wanna take it and extract each line into some vars to use them: colour[0]=255; colour[1]=250; colour[2]=250; string=snow (255 250 250); (the vars will be reused with each line)

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