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  • small string optimization for vector?

    - by BuschnicK
    I know several (all?) STL implementations implement a "small string" optimization where instead of storing the usual 3 pointers for begin, end and capacity a string will store the actual character data in the memory used for the pointers if sizeof(characters) <= sizeof(pointers). I am in a situation where I have lots of small vectors with an element size <= sizeof(pointer). I cannot use fixed size arrays, since the vectors need to be able to resize dynamically and may potentially grow quite large. However, the median (not mean) size of the vectors will only be 4-12 bytes. So a "small string" optimization adapted to vectors would be quite useful to me. Does such a thing exist? I'm thinking about rolling my own by simply brute force converting a vector to a string, i.e. providing a vector interface to a string. Good idea?

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  • Samsung UMPC, Built in Camera doesn't support DirectX how can I use it?

    - by Markive
    The Samsung Q1 Ultra, is the perfect device for my software except that the built in camera seems to be incompatible with standard DirectX drivers, so my .Net camera implementation can't use the device. I have limited experience in this area.. Even Skype can't access this camera, but a little program from Samsung can.. I've looked at the program's assemblies and it's too obfuscated to see inside so I can't see anyway to use them.. What sort of camera could this be? Are there any .Net classes / implementations I can use to access this camera?

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  • Preventing dictionary attacks on a web application

    - by Kevin Pang
    What's the best way to prevent a dictionary attack? I've thought up several implementations but they all seem to have some flaw in them: Lock out a user after X failed login attempts. Problem: easy to turn into a denial of service attack, locking out many users in a short amount of time. Incrementally increase response time per failed login attempt on a username. Problem: dictionary attacks might use the same password but different usernames. Incrementally increase response time per failed login attempt from an IP address. Problem: easy to get around by spoofing IP address. Incrementally increase response time per failed login attempt within a session. Problem: easy to get around by creating a dictionary attack that fires up a new session on each attempt.

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  • getting started with qpid server

    - by London
    I'd like to get started with qpid, can anyone recommend some useful resources/links/code examples for me to study? I'm interested about java implementations?I'd like to create message sender/listener. I've already done messaging with jboss where I send the message to the queue and the listener picks it up from there, what is different with qpid? Is it the same only replacing jboss as a server with qpid or?I'm new to all of this it might sound weird when I ask it. Oh yes similar question: http://stackoverflow.com/questions/1693099/get-started-with-qpid Doesn't really help me much. Any hints would help me a lot. thank you

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  • In CQRS (event-sourced), do you need a global sequence counter in the event store?

    - by Jon M
    In trying to get my head around CQRS (and DDD in general) I have come across situations when two events occur on different aggregates but the order of them has domain meaning. If so then they could happen so close together that a timestamp (as used by the sample implementations I have seen) cannot differentiate them, meaning the event store doesn't contain a 'complete' representation of the domain as there is ambiguity over the order in which events occurred. As an example, the domain could fire a CustomerCreatedEvent which applies to the Customer aggregate, and then a CustomerAssignedToAgent event on the Agent aggregate. The CustomerAssignedToAgent event doesn't make sense if it occurs before the CustomerCreatedEvent, but typically both of these might be fired as a result of one operation which makes it likely that the timestamps would effectively be the same. So am I just modelling things badly? Should there ever be a situation where the sequence of events across different aggregates is important? Or should you keep a global sequence number on your event store, so that you can identify the exact sequence in which events occurred?

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  • Searching for a complex and well-designed PHP OOP application to learn from

    - by Raveren
    Basically, I am diving ever deeper into complex programming practices. I've almost no friends that are experienced (or more experienced than me) programmers to learn from, so I am looking for the next best thing - learning from the work of strangers. Can anyone recommend a real world finished and working application written well and OOP-centered. I'd like to take and analyze its source. Bonus if it's based on Zend Framework. What I am interested most in is objects that unlike desktop applications, have only one real operation done to them (or to their representation in DB or session) during their lifetime (or pageload), like user-logIn(). I'm interested in optimal and reusable design patterns and their real life implementations.

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  • Formating phone numbers

    - by Sven
    Our customers often fill out "incorrect" formated phone-numbers. Do anyone know if there is any lib or standard to convert numbers into a more international style? This is a Swedish example but we have customers around the globe and i don't what to manually handle implementations for everyone. input often is like this: 0555 11122 and the wanted result is something like this: +46(0)555-11122 I can do the formating myself but different countries have different variations and systems so a C/Java/C# lib or a standard method to handle this would be great.

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  • PyPy: What is all the buzz about?

    - by sub
    Note: The title is provocating (to make you click on it and want to close-vote the question) and I don't want to look preoccupated. Since some time now I read and heard more and more about PyPy. It's like a linear graph. Why is PyPy so special? As far as I know implementations of dynamic languages written in the languages itself aren't such a rare thing, or am I not getting something? Some even people call PyPy "the future" [of python], or see some sort of deep potential in this implementation. What exactly is the meaning of this?

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  • How can a language be interpreted by itself (like Rubinius)?

    - by japancheese
    I've been programming in Ruby for a while now with just the standard MRI implementation of Ruby, but I've always been curious about the other implementations I hear so much about. I was reading about Rubinius the other day, a Ruby interpreter written in Ruby. I tried looking it up in various places, but I was having a hard time figuring out exactly how something like this works. I've never had much experience in compilers or language writing but I'm really interested to figure it out. How exactly can a language be interpreted by itself? Is there a basic step in compiling that I don't understand where this makes sense? Can someone explain this to me like I'm an idiot (because that wouldn't be too far off base anyways)

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  • Should every class have its own namespace?

    - by thehouse
    Something that has been troubling me for a while: The current wisdom is that types should be kept in a namespace that only contains functions which are part of the type's non-member interface (see C++ Coding Standards Sutter and Alexandrescu or here) to prevent ADL pulling in unrelated definitions. Does this imply that all classes must have a namespace of their own? If we assume that a class may be augmented in the future by the addition of non-member functions, then it can never be safe to put two types in the same namespace as either one of them may introduce non-member functions that could interfere with the other. The reason I ask is that namespaces are becoming cumbersome for me. I'm writing a header-only library and I find myself using classes names such as project::component::class_name::class_name. Their implementations call helper functions but as these can't be in the same namespace they also have to be fully qualified!

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  • DDD Infrastructure services

    - by Zygimantas
    Hello, I am learning DDD and I am a little bit lost in Infrastructure layer: As I understand, "all good DDD applications" should have 4 layers: Presentation, Application, Domain and Infrastructure. Database should be accessed using Repositories. Repository interfaces should be in Domain layer and repository implementation - in Infrastructure (reference http://stackoverflow.com/questions/693221/ddd-where-to-keep-domain-interfaces-the-infrastructure). Application, Domain and Infrastructure layer should/may have services (reference www.lostechies.com/blogs/jimmy_bogard/archive/2008/08/21/services-in-domain-driven-design.aspx), in example EmailService in Infrastructure layer which sends Email messages. BUT, inside Infrastructure layer we have repository implementations, which are used to access database. So, in this case, repositories are database services? What is the difference between Infrastructure service and repository? Thanks in advance!

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  • super-space-optimized code

    - by Will
    There are key self-contained algorithms - particularly cryptography-related such as AES, RSA, SHA1 etc - which you can find many implementations of for free on the internet. Some are written to be nice and portable clean C. Some are written to be fast - often with macros, and explicit unrolling. As far as I can tell, none are trying to be especially super-small - so I'm resigned to writing my own - explicitly AES128 decryption and SHA1 for ARM THUMB2. What patterns and tricks can I use to do so? Are there compilers/tools that can roll-up code?

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  • Disposing a Bitmap through its Finalizer

    - by devoured elysium
    I have a complex program in which I have to first create, then use wrappers around bitmaps and send them across a lot of different classes. The problem in the end is deciding which classes should dispose the bitmaps. Most of the time the end classes don't know if they can indeed dispose the bitmap as the same bitmap can be used in several places. Also, I can't just copy the bitmaps because this is a kind of resource intensive algorithm and doing it would be dead slow. I looked up on reflector for Image/Bitmap's implementations and they seem to use the Dispose Pattern. So, even if I don't call Dispose(), the CLR will eventually call it some other time. Is it too bad if I just let the bitmaps be as they are, and let the finalizer take care of them?

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  • Detecting coincident subset of two coincident line segments

    - by Jared Updike
    This question is related to: How do I determine the intersection point of two lines in GDI+? (great explanation of algebra but no code) How do you detect where two line segments intersect? (accepted answer doesn't actually work) But note that an interesting sub-problem is completely glossed over in most solutions which just return null for the coincident case even though there are three sub-cases: coincident but do not overlap touching just points and coincident overlap/coincident line sub-segment For example we could design a C# function like this: public static PointF[] Intersection(PointF a1, PointF a2, PointF b1, PointF b2) where (a1,a2) is one line segment and (b1,b2) is another. This function would need to cover all the weird cases that most implementations or explanations gloss over. In order to account for the weirdness of coincident lines, the function could return an array of PointF's: zero result points (or null) if the lines are parallel or do not intersect (infinite lines intersect but line segments are disjoint, or lines are parallel) one result point (containing the intersection location) if they do intersect or if they are coincident at one point two result points (for the overlapping part of the line segments) if the two lines are coincident

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  • Visual Studio IDE - how do you quickly find the implementation(s) of an interface's method?

    - by Jess
    Is there a quick way to find all of the implementations of, not references to, an interface's method/property/etc? Here's some sample code: public class SomeClass : IBaseClass { public Int32 GetInt() { return 1; } } public interface IBaseClass { public Int32 GetInt(); } public class SomeOtherClass { ISomeClass _someClass; private TestMethod() { _someClass = new SomeClass(); _someClass.GetInt(); } } I want to quickly get to SomeClass.GetInt() while reviewing SomeOtherClass.TestMethod(). If I right click on _someClass.GetInt() and click 'Go To Definition', it takes me to the interface. If I click 'Find All References', I could potentially see a list of all uses ... not just the classes that implement the GetInt() method. Is there a faster way to find this? Any tips from other developers? We are using D.I. for most of our dependencies, which means that tracing through deeply nested code takes forever.

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  • Is this a valid, lazy, thread-safe Singleton implementation for C#?

    - by Matthew
    I implemented a Singleton pattern like this: public sealed class MyClass { ... public static MyClass Instance { get { return SingletonHolder.instance; } } ... static class SingletonHolder { public static MyClass instance = new MyClass (); } } From Googling around for C# Singleton implementations, it doesn't seem like this is a common way to do things in C#. I found one similar implementation, but the SingletonHolder class wasn't static, and included an explicit (empty) static constructor. Is this a valid, lazy, thread-safe way to implement the Singleton pattern? Or is there something I'm missing?

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  • Static assembly initialization

    - by ph0enix
    I'm attempting to develop an Interceptor framework (in C#) where I can simply implement some interfaces, and through the use of some static initialization, register all my Interceptors with a common Dispatcher to be invoked at a later time. The problem lies in the fact that my Interceptor implementations are never actually referenced by my application so the static constructors never get called, and as a result, the Interceptors are never registered. If possible, I would like to keep all references to my Interceptor libraries out of my application, as this is my way of (hopefully) enforcing loose coupling across different modules. Hopefully this makes some sense. Let me know if there's anything I can clarify... Does anyone have any ideas, or perhaps a better way to go about implementing my Interceptor pattern? TIA, Jeremy

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  • Google App Engine, Java, and HTTP Performance

    - by polyclef
    A friend and I are currently working on a turn-based game with chat with both desktop browser and Android clients, with Google App Engine as the server. We're using the Java API for GAE and using HTTP for communication with the server. We've implemented simple chat functionality, and we're getting undesirable latencies 1-3 seconds from both the browser and Android clients while just posting simple one-word chat messages. My friend thought it would be best to use XMPP instead of HTTP, but we want to use a Google Accounts cookie for authentication from the Android client, and according to the GAE documentation, XMPP clients cannot use a Google Accounts cookie and must use the user's password. Does anyone have any suggestions as to where the latency might be coming from, how to troubleshoot it, and/or what to do about it? Also, is anyone aware of any opensource implementations of chat (or something similar) on GAE done in Java? Can't seem to find any.

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  • Do you know of a C dictionary that supports COW transactions?

    - by Tim Post
    I'm looking for a key - value dictionary library written in C that supports a theoretically unlimited number of cheap transactions. I'd like to have one dictionary in memory, with hundreds of threads starting transactions, possibly modifying the dictionary, ending (completing) the transaction or potentially aborting the transaction. Only 50% of the time will these threads actually modify the dictionary. Most dictionary transaction implementations that I've seen copy always, instead of copying on write, whenever a transaction is started. Given the expected size ( 1GB) of the dictionary, I'm hoping to find something that COWs only when something is actually changed during a transaction. I'm also hoping for something that is packaged by most major GNU/Linux distributions. Any suggestions or links are very much appreciated.

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  • What is the best solution to replace a new memory allocator in an existing code?

    - by O. Askari
    During the last few days I've gained some information about memory allocators other than the standard malloc(). There are some implementations that seem to be much better than malloc() for applications with many threads. For example it seems that tcmalloc and ptmalloc have better performance. I have a C++ application that uses both malloc and new operators in many places. I thought replacing them with something like ptmalloc may improve its performance. But I wonder how does the new operator act when used in C++ application that runs on Linux? Does it use the standard behavior of malloc or something else? What is the best way to replace the new memory allocator with the old one in the code? Is there any way to override the behavior or new and malloc or do I need to replace all the calls to them one by one?

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  • Javascript : where are high level data structures?

    - by user355056
    Hi! I'm writing a client program for a game in Javascript but I'm new in Javascript world. Core Javascript lack of high level data structures. I've found code snippets on internet but I'm looking for a reference library (like commons-collection or google-collection in java world). I found this post: http://stackoverflow.com/questions/2523436/javascript-implementation-of-a-set-data-structure which refers to jshashtable and closure. Are they reference implementations? Do you know something else? Thanks

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  • Comapring pitches with digital audio

    - by user2250569
    I work on application which will compare musical notes with digital audio. My first idea was analyzes wav file (or sound in real-time) with some polyphonic pitch algorithms and gets notes and chords from this file and subsequently compared with notes in dataset. I went through a lot of pages and it seems to be a lot of hard work because existing implementations and algorithms are mainly/only focus on monophonic sound. Now, I got the idea to do this in the opposite way. In dataset I have for example note: A4 or better example chord: A4 B4 H4. And my idea is make some wave (or whatever I don't know what) from this note or chord and then compared with piece of digital audio. Is this good idea? Is it better/harder solution? If yes can you recommend me how to do it?

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  • Inheriting and overriding interfaces in C#

    - by Daniel A. White
    Please note: I am writing this question. I have these interfaces in a library/framework I am working on: interface IRepository<TKey,TModel> { void Remove(TModel entity); } interface IRepository<T> : IRepository<int, T> { } interface ISoftDeleteRepository<TKey,TModel> : IRepository<TKey, TModel> { } interface ISoftDeleteRepository<TModel> : ISoftDeleteRepository<int, TModel>, IRepository<TModel> { } and these implementations class Repository : IRepository { void Remove(TModel entity) { // actually Delete } } interface IRepository<T> : IRepository<int, T> { } interface ISoftDeleteRepository<TKey,TModel> : IRepository<TKey, TModel> { } interface ISoftDeleteRepository<TModel> : ISoftDeleteRepository<int, TModel>, IRepository<TModel> { }

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  • C++0x implementation guesstimates?

    - by dsimcha
    The C++0x standard is on its way to being complete. Until now, I've dabbled in C++, but avoided learning it thoroughly because it seems like it's missing a lot of modern features that I've been spoiled by in other languages. However, I'd be very interested in C++0x, which addresses a lot of my complaints. Any guesstimates, after the standard is ratified, as to how long it will take for major compiler vendors to provide reasonably complete, production-quality implementations? Will it happen soon enough to reverse the decline in C++'s popularity, or is it too little, too late? Do you believe that C++0x will become "the C++" within a few years, or do you believe that most people will stick to the earlier standard in practice and C++0x will be somewhat of a bastard stepchild, kind of like C99?

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  • Guidelines for solution source code organisation(OO/DDD)

    - by fearofawhackplanet
    I'm starting on my first business project (.NET) and am trying to follow DDD principles. Are there any guidelines or common patterns for orgaining source code and namespaces? For example, do your domain objects go in a namespace MyProject.Domain or whatever? Would you separate the concrete implementations and the interfaces? In different namespaces? Different folders? Different solutions? I know a lot of this is subjective and dependent on project size, but a few pointers or suggestions to get started on a relatively small but extensible n-tier project would be useful.

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