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  • STLifying C++ classes

    - by shambulator
    I'm trying to write a class which contains several std::vectors as data members, and provides a subset of vector's interface to access them: class Mesh { public: private: std::vector<Vector3> positions; std::vector<Vector3> normals; // Several other members along the same lines }; The main thing you can do with a mesh is add positions, normals and other stuff to it. In order to allow an STL-like way of accessing a Mesh (add from arrays, other containers, etc.), I'm toying with the idea of adding methods like this: public: template<class InIter> void AddNormals(InIter first, InIter last); Problem is, from what I understand of templates, these methods will have to be defined in the header file (seems to make sense; without a concrete iterator type, the compiler doesn't know how to generate object code for the obvious implementation of this method). Is this actually a problem? My gut reaction is not to go around sticking huge chunks of code in header files, but my C++ is a little rusty with not much STL experience outside toy examples, and I'm not sure what "acceptable" C++ coding practice is on this. Is there a better way to expose this functionality while retaining an STL-like generic programming flavour? One way would be something like this: (end list) class RestrictedVector<T> { public: RestrictedVector(std::vector<T> wrapped) : wrapped(wrapped) {} template <class InIter> void Add(InIter first, InIter last) { std::copy(first, last, std::back_insert_iterator(wrapped)); } private: std::vector<T> wrapped; }; and then expose instances of these on Mesh instead, but that's starting to reek a little of overengineering :P Any advice is greatly appreciated!

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  • Implement abstract class as a local class? pros and cons

    - by sinec
    Hi, for some reason I'm thinking on implementing interface within a some function(method) as local class. Consider following: class A{ public: virtual void MethodToOverride() = 0; }; A * GetPtrToAImplementation(){ class B : public A { public: B(){} ~B(){} void MethodToOverride() { //do something } }; return static_cast<A *>(new B()); } int _tmain(int argc, _TCHAR* argv[]) { A * aInst = GetPtrToAImplementation(); aInst->MethodToOverride(); delete aInst; return 0; } the reason why I'm doing this are: I'm lazy to implement class (B) in separate files MethodToOverride just delegates call to other class Class B shouldn't be visible to other users no need to worry about deleting aInst since smart pointers are used in real implementation So my question is if I'm doing this right? Thanks in advance!

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  • UI to allow 700+ multiple choices

    - by Refracted Paladin
    In my desktop .NET application I have written(for internal use) where I need to allow my users to apply diagnosis's to a Member Plan. There are currently 700 in the system and growing. I need to allow them to add multiple diapnosis's at once. I currently am allowing this through a combo check list box. This works but is INSANELY unweildly for both myself and the users. What I am looking for is a how I could go about displaying these to the users. Ideally I would need to show two criteria for each each as well. Diagnosis Name and Diagnosis Code Ideas? How would you tackle this? I am using .Net 3.5sp1 and SQL 2005 for the backend. I don't care if the solution is WPF or Winforms.

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  • new Integer vs valueOf

    - by LB
    Hi, I was using Sonar to make my code cleaner, and it pointed that I'm using new Integer(1) instead of Integer.valueOf(1). Because it seems that valueOf does not instantiate a new object so is more memory-friendly. How can valueOf not instantiate a new object ? How does it work ? Is this true for all integers ? thanks.

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  • Am i using too much jquery? When i'm crossing the line?

    - by Andrea
    Lately i find myself using jquery and javascript a lot, often to do the same things that i did before using css. For example, i alternate table rows color or create buttons and links hover effects using javascript/jquery. Is this acceptable? Or should i keep using css for these kind of things? So the real question is: When i'm using too much jquery? How can i understand when i'm crossing the line? Thanks.

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  • Call a non member function on an instance before is constructed.

    - by Tom
    Hi everyone. I'm writing a class, and this doubt came up. Is this undef. behaviour? On the other hand, I'm not sure its recommended, or if its a good practice. Is it one if I ensure no exceptions to be thrown in the init function? //c.h class C{ float vx,vy; friend void init(C& c); public: C(); }; //c.cpp C::C() { init(*this); } void init(C& c) //throws() to ensure no exceptions ? { c.vx = 0; c.vy = 0; } Thanks in advance

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  • How should I use try...except while defining a function?

    - by SpawnCxy
    Hi all, I find I've been confused by the problem that when I needn't to use try..except.For last few days it was used in almost every function I defined which I think maybe a bad practice.For example: class mongodb(object): def getRecords(self,tname,conditions=''): try: col = eval("self.db.%s" %tname) recs = col.find(condition) return recs except Exception,e: #here make some error log with e.message What I thought is ,exceptions may be raised everywhere and I have to use try to get them. And my question is,is it a good practice to use it everywhere when defining functions?If not are there any principles for it?Help would be appreciated! Regards

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  • If you could remove one feature of php ti help newbies what would it be?

    - by Chris
    If you could remove one feature from PHP so as to discourage, prevent or otherwise help stop newer programmers develop bad habits or practices, or, to stop them falling into traps that might hinder their development skills what would it be and why? Now, before the votes to close it's not as open-ended as you might think. I'm not asking purely what is the worst feature or what feature would you really like to remove purely arbitrarily. Yes, there may not be one correct answer but I suspect there will be many similar answers which will provide me with a good idea of things I might be doing wrong, even inadvertently.

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  • Correct approach to validate attributes of an instance of class

    - by systempuntoout
    Having a simple Python class like this: class Spam(object): __init__(self, description, value): self.description = description self.value = value Which is the correct approach to check these constraints: "description cannot be empty" "value must be greater than zero" Should i: 1.validate data before creating spam object ? 2.check data on __init__ method ? 3.create an is_valid method on Spam class and call it with spam.isValid() ? 4.create an is_valid static method on Spam class and call it with Spam.isValid(description, value) ? 5.check data on setters declaration ? 6.... Could you recommend a well designed\Pythonic\not verbose (on class with many attributes)\elegant approach?

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  • Best way to support large dropdowns

    - by JustAProgrammer
    Say I have a report that can be restricted by specifying some value in a dropdown. This dropdown list references a table with 30,000 records. I don't think this would be feasible to populate a dropdown with! So, what is the best way to provide the user the ability to select a value given this situation? These values do not really have categories and even if I subdivided (by having some nesting dropdown situation) by the first letter of the value, that may still leave a few thousand entries. What's the best way to deal with this?

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  • Is it bad practice to initialize a variable to a dummy value?

    - by froadie
    This question is a result of the answers to this question that I just asked. It was claimed that this code is "ugly" because it initializes a variable to a value that will never be read: String tempName = null; try{ tempName = buildFileName(); } catch(Exception e){ ... System.exit(1); } FILE_NAME = tempName; Is this indeed bad practice? Should one avoid initializing variables to dummy values that will never actually be used? (EDIT - And what about initializing a String variable to "" before a loop that will concatenate values to the String...? Or is this in a separate category? e.g. String whatever = ""; for(String str : someCollection){ whatever += str; } )

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  • When using Sessions is bad thing, and whats wrong with it?

    - by Amr ElGarhy
    I know that in community server which means that you can't use Sessions, and few years ago i remember i was working on a website where we were not allowed to use sessions. In my point of view sessions are a very helpful tool if we managed how to use the right way, but is using session variable in a website is something bad, when its bad and when its not?

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  • Flexible array members in C - bad?

    - by Lionel
    I recently read that using flexible array members in C was poor software engineering practice. However, that statement was not backed by any argument. Is this an accepted fact? (Flexible array members are a C feature introduced in C99 whereby one can declare the last element to be an array of unspecified size. For example: ) struct header { size_t len; unsigned char data[]; };

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  • Do I need to cast the result of strtol to int?

    - by Kristo
    The following code does not give a warning with g++ 4.1.1 and -Wall. int octalStrToInt(const std::string& s) { return strtol(s.c_str(), 0, 8); } I was expecting a warning because strtol returns a long int but my function is only returning a plain int. Might other compilers emit a warning here? Should I cast the return value to int in this case as a good practice?

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  • list all files from directories and subdirectories in Java

    - by Adnan
    What would be the fastest way to list the names of files from 1000+ directories and sub-directories? EDIT; The current code I use is: import java.io.File; public class DirectoryReader { static int spc_count=-1; static void Process(File aFile) { spc_count++; String spcs = ""; for (int i = 0; i < spc_count; i++) spcs += " "; if(aFile.isFile()) System.out.println(spcs + "[FILE] " + aFile.getName()); else if (aFile.isDirectory()) { System.out.println(spcs + "[DIR] " + aFile.getName()); File[] listOfFiles = aFile.listFiles(); if(listOfFiles!=null) { for (int i = 0; i < listOfFiles.length; i++) Process(listOfFiles[i]); } else { System.out.println(spcs + " [ACCESS DENIED]"); } } spc_count--; } public static void main(String[] args) { String nam = "D:/"; File aFile = new File(nam); Process(aFile); } }

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  • Avoiding repetition with libraries that use a setup + execute model

    - by lijie
    Some libraries offer the ability to separate setup and execution, esp if the setup portion has undesirable characteristics such as unbounded latency. If the program needs to have this reflected in its structure, then it is natural to have: void setupXXX(...); // which calls the setup stuff void doXXX(...); // which calls the execute stuff The problem with this is that the structure of setupXXX and doXXX is going to be quite similar (at least textually -- control flow will prob be more complex in doXXX). Wondering if there are any ways to avoid this. Example: Let's say we're doing signal processing: filtering with a known kernel in the frequency domain. so, setupXXX and doXXX would probably be something like... void doFilter(FilterStuff *c) { for (int i = 0; i < c->N; ++i) { doFFT(c->x[i], c->fft_forward_setup, c->tmp); doMultiplyVector(c->tmp, c->filter); doFFT(c->tmp, c->fft_inverse_setup, c->x[i]); } } void setupFilter(FilterStuff *c) { setupFFT(..., &(c->fft_forward_setup)); // assign the kernel to c->filter ... setupFFT(..., &(c->fft_inverse_setup)); }

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  • When using out parameters in a function, is it good practice to initialize them in the function?

    - by adambox
    I have a function that uses out parameters to return multiple values to the caller. I would like to initialize them in the function, but I wasn't sure if that's a bad idea since you don't know when you call the function that it's going to change the values right away. The caller might assume that after the function returns, if whatever it was doing didn't work, the values would be whatever they were initialized to in the caller. Is it ok / good for me to initialize in the function? Example: public static void SomeFunction(int ixID, out string sSomething) { sSomething = ""; sSomething = something(ixID); if (sSomething = "") { somethingelse(); sSomething = "bar" } }

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  • Should I create a new extension for an xml file?

    - by macleojw
    I'm working with a data model stored in XML files. I want to create some metadata for the model and store it alongside, but would like to be able to distinguish between the two. The data model is imported into some software from time to time and we don't want it to try to import the meta data files. To get round this, I've been thinking of creating a new extension for the metadata xml files (say .mdml). Is this good practice?

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  • Secrets of delivering .NET size large products?

    - by Joan Venge
    In software companies I have seen it's really hard to work on very large products where everything depends on everything else. For instance Microsoft works on C#, F#, .NET, WPF, Visual Studio where these things are interconnected. I don't know how many people are involved, but if it's in 100s, how do they keep in sync with everything, so they design and implement features without conflicting with other dependencies and future plans of other products? I am wondering that if MS is able to do this, they must have a very good system. Any guidelines or secrets for MS or non-MS very large software product delivering?

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  • Creating and Compiling a C++ project on Windows

    - by sc_ray
    I need to work on C++ project on my windows machine. My project will consist of various classes(.h and .cpp) as well as the startup file to start the application. The preliminary design is simple but the application has the potential to gain complexity as time goes by. What I need here is ideas to set up the C++ project compiler/IDE/Makefile etc..etc. as well as some standard tools besides Visual C++ to compile/build/link projects such as these on a Windows OS. Thanks

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  • Fastest way to check for value existance.

    - by Itay Moav
    I have a list of values I have to check my input against it for existence. What is the faster way? This is really out of curiosity on how the internals work, not any stuff about premature optimization etc... 1. $x=array('v'=>'','c'=>'','w'=>); .. .. array_key_exists($input,$x); 2. $x=array('v','c','w'); .. .. in_array($input,$x);

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  • Defining implicit and explicit casts for C# interfaces

    - by ehdv
    Is there a way to write interface-based code (i.e. using interfaces rather than classes as the types accepted and passed around) in C# without giving up the use of things like implicit casts? Here's some sample code - there's been a lot removed, but these are the relevant portions. public class Game { public class VariantInfo { public string Language { get; set; } public string Variant { get; set; } } } And in ScrDictionary.cs, we have... public class ScrDictionary: IScrDictionary { public string Language { get; set; } public string Variant { get; set; } public static implicit operator Game.VariantInfo(ScrDictionary s) { return new Game.VariantInfo{Language=sd.Language, Variant=sd.Variant}; } } And the interface... public interface IScrDictionary { string Language { get; set; } string Variant { get; set; } } I want to be able to use IScrDictionary instead of ScrDictionary, but still be able to implicitly convert a ScrDictionary to a Game.VariantInfo. Also, while there may be an easy way to make this work by giving IScrDictionary a property of type Game.VariantInfo my question is more generally: Is there a way to define casts or operator overloading on interfaces? (If not, what is the proper C# way to maintain this functionality without giving up interface-oriented design?)

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