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• Missing line number in stack trace eventhough the PDB files are included

  - by Farzad

  This is running me nuts. I have this web service implemented w/ C# using VS 2008. I publish it on IIS. I have modified the release build so the pdb files are copied along with the dlls into the target directory on inetpub. Also web.config file has debug=true. Then I call a web service that throws an exception. The stack trace does not contain the line numbers. I have no idea what I am missing here, any ideas? Additional Info: If I run the web app using VS built-in web server, it works and I get line numbers in stack trace. But if I copy the same files (pdb and dll) that the VS built-in web server is using to IIS, still the line numbers are missing in stack trace. It seems that there is something related to the IIS that ignores the pdb files! Update When I publish to IIS, all the pdb files are published under the bin directory and everything looks fine. But when I go to "C:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files" under the specific directory related to my project, I can see that the assembly (.dll) files are all there, but there is no pdb files. But this does not happen if I run the project using VS built-in web server. So if I copy the pdb files manually to the temp folder, I can see the line numbers. Any idea why the pdb files are not copied to the temp folder? BTW, when I attach to the worker process I can see that it says Symbols loaded!

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• Locate modules by stack address

  - by PaulH

  I have a Winodws Mobile 6.1 application running on an ARMV4I processor. Given a stack address (from unwinding an exception), I like to determine what module owns that address. Using the ToolHelpAPI, I'm able to determine most modules using the following method: HANDLE snapshot = ::CreateToolhelp32Snapshot( TH32CS_SNAPMODULE | TH32CS_GETALLMODS, 0 ); if( INVALID_HANDLE_VALUE != snapshot ) { MODULEENTRY32 mod = { 0 }; mod.dwSize = sizeof( mod ); if( ::Module32First( snapshot, &mod ) ) { do { if( stack_address > (DWORD)mod.modBaseAddr && stack_address < (DWORD)( mod.modBaseAddr + mod.modBaseSize ) ) { // Found the module! // offset = stack_address - mod.modBaseAddr break; } } while( ::Module32Next( snapshot, &mod ) ); } ::CloseToolhelp32Snapshot( snapshot ); } But, I don't always seem to be able to find a module that matches an address. For example: stack address module offset 0x03f65bd8 coredll.dll + 0x0001bbd8 0x785cab1c mylib.dll + 0x0002ab1c 0x785ca9e8 mylib.dll + 0x0002a9e8 0x785ca0a0 mylib.dll + 0x0002a0a0 0x785c8144 mylib.dll + 0x00028144 0x3001d95c ??? 0x3001dd44 ??? 0x3001db90 ??? 0x03f88030 coredll.dll + 0x0003e030 0x03f8e46c coredll.dll + 0x0004446c 0x801087c4 ??? 0x801367b4 ??? 0x8010ce78 ??? 0x801086dc ??? 0x03f8e588 coredll.dll + 0x00044588 0x785a56a4 mylib.dll + 0x000056a4 0x785bdd60 mylib.dll + 0x0001dd60 0x785bbd0c mylib.dll + 0x0001bd0c 0x785bdb38 mylib.dll + 0x0001db38 0x3001db20 ??? 0x3001dc40 ??? 0x3001a8a4 ??? 0x3001a79c ??? 0x03f67348 coredll.dll + 0x0001d348 Where do I find those stack addresses that are missing? Any suggestions? Thanks, PaulH

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• Flex: View Stack Navigator

  - by Deena

  Hi, I have a component mxml file in which i have a view stack, on click of a button i navigate to the first child, now i need to navigate to the second child during onclick of a button present in the second child. All the childs are component files included within the view stack. How could this be done, Sample code is present below, --------------------Application.mxml--------------------- <mx:Canvas xmlns:mx="http://www.adobe.com/2006/mxml" > <mx:Script> <![CDATA[ private function loadScreen():void { navigationViewStack.selectedChild=id_offering; } ]]> </mx:Script> <mx:Button label="Save" click="loadScreen();"/> </mx:Canvas> <mx:ViewStack id="navigationViewStack" width="100%" height="100%"> <components:dashboard id="id_dashboard" label="Dashboard" /> <components:offering id="id_offering" label="Offering" /> <components:IssueSec id="id_issueSec" label = "Issues"/> </mx:ViewStack> -------------------------Ends-------------------------------------- Now in my offering.mxml file if i try to access navigationViewStack i am getting an error stating 'Access of undefined property navigationViewStack. Help me on how to access the view stack from my component mxml file. Thanks! Cheers, Deena

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• stack overflow problem in program

  - by Jay

  So I am currently getting a strange stack overflow exception when i try to run this program, which reads numbers from a list in a data/text file and inserts it into a binary search tree. The weird thing is that when the program works when I have a list of 4095 numbers in random order. However when i have a list of 4095 numbers in increasing order (so it makes a linear search tree), it throws a stack overflow message. The problem is not the static count variable because even when i removed it, and put t=new BinaryNode(x,1) it still gave a stack overflow exception. I tried debugging it, and it broke at if (t == NULL){ t = new BinaryNode(x,count); Here is the insert function. BinaryNode *BinarySearchTree::insert(int x, BinaryNode *t) { static long count=0; count++; if (t == NULL){ t = new BinaryNode(x,count); count=0; } else if (x < t->key){ t->left = insert(x, t->left); } else if (x > t->key){ t->right = insert(x, t->right); } else throw DuplicateItem(); return t; }

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• Linux network stack : adding protocols with an LKM and dev_add_pack

  - by agent0range

  Hello, I have recently been trying to familiarize myself with the Linux Networking stack and device drivers (have both similarly named O'Reilly books) with the eventual goal of offloading UDP. I have already implemented UDP on the NIC but now the hard part... Rather than ask for assistance on this larger goal I was hoping someone could clarify for me a particular snippet I found that is part of a LKM which registeres a new protocol (OTP) that acts as a filter between the device driver and network stack. http://www.phrack.org/archives/55/p55_0x0c_Building%20Into%20The%20Linux%20Network%20Layer_by_lifeline%20&%20kossak.txt (Note: this Phrack article contains three different modules, code for the OTP is at the bottom of the page) In the init function of his example he has: otp_proto.type = htons(ETH_P_ALL); otp_proto.func = otp_func; dev_add_pack(&otp_proto); which (if I understand correctly) should register otp_proto as a packet sniffer and put it into the ptype_all data structure. My question is about the dev_add_pack. Is it the case that the protocol being registered as a filter will always be placed at this layer between L2 and the device driver? Or, for instance could I make such a filtering occur between the application and transport layers (analyze socket parameters) using the same process? I apologize if this is confusing - I am having some trouble wrapping my head around the bigger picture when it comes to modules altering kernel stack functionality. Thanks

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• Setting the default stack size on Linux globally for the program

  - by wowus

  So I've noticed that the default stack size for threads on linux is 8MB (if I'm wrong, PLEASE correct me), and, incidentally, 1MB on Windows. This is quite bad for my application, as on a 4-core processor that means 64 MB is space is used JUST for threads! The worst part is, I'm never using more than 100kb of stack per thread (I abuse the heap a LOT ;)). My solution right now is to limit the stack size of threads. However, I have no idea how to do this portably. Just for context, I'm using Boost.Thread for my threading needs. I'm okay with a little bit of #ifdef hell, but I'd like to know how to do it easily first. Basically, I want something like this (where windows_* is linked on windows builds, and posix_* is linked under linux builds) // windows_stack_limiter.c int limit_stack_size() { // Windows impl. return 0; } // posix_stack_limiter.c int limit_stack_size() { // Linux impl. return 0; } // stack_limiter.cpp int limit_stack_size(); static volatile int placeholder = limit_stack_size(); How do I flesh out those functions? Or, alternatively, am I just doing this entirely wrong? Remember I have no control over the actual thread creation (no new params to CreateThread on Windows), as I'm using Boost.Thread.

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• Struts2 Value Stack

  - by vipul12389

  I want to understand Struts 2 value stack vs request scope. I want the struts2 value stack to work same as request scope. for e.g. i have invoked action1 in struts 2, the action performs some db task and gets back. it performs some operation on a object called cases (type Cases, where Cases is bean class with getters and setters). cases object is declared at class level. action1 led a view to be rendered say jsp1. jsp1 again has some action called as action2. action2 leads to the same java file as of action1 but has different method. Now, i want to access the object which was used in action1. during action1 cases was pushed to Value Stack and was accessed on jsp1. I simply tried accessing its getter methods, but it returns a null value....!! any solution on how to do ??? or is it possible ?? i know if its possible then what is the difference between vs and request scope...

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• When are Getters and Setters Justified

  - by Winston Ewert

  Getters and setters are often criticized as being not proper OO. On the other hand most OO code I've seen has extensive getters and setters. When are getters and setters justified? Do you try to avoid using them? Are they overused in general? If your favorite language has properties (mine does) then such things are also considered getters and setters for this question. They are same thing from an OO methodology perspective. They just have nicer syntax. Sources for Getter/Setter Criticism (some taken from comments to give them better visibility): http://www.javaworld.com/javaworld/jw-09-2003/jw-0905-toolbox.html http://typicalprogrammer.com/?p=23 http://c2.com/cgi/wiki?AccessorsAreEvil http://www.darronschall.com/weblog/2005/03/no-brain-getter-and-setters.cfm http://www.adam-bien.com/roller/abien/entry/encapsulation_violation_with_getters_and To state the criticism simply: Getters and Setters allow you to manipulate the internal state of objects from outside of the object. This violates encapsulation. Only the object itself should care about its internal state. And an example Procedural version of code. struct Fridge { int cheese; } void go_shopping(Fridge fridge) { fridge.cheese += 5; } Mutator version of code: class Fridge { int cheese; void set_cheese(int _cheese) { cheese = _cheese; } int get_cheese() { return cheese; } } void go_shopping(Fridge fridge) { fridge.set_cheese(fridge.get_cheese() + 5); } The getters and setters made the code much more complicated without affording proper encapsulation. Because the internal state is accessible to other objects we don't gain a whole lot by adding these getters and setters. The question has been previously discussed on Stack Overflow: http://stackoverflow.com/questions/565095/java-are-getters-and-setters-evil http://stackoverflow.com/questions/996179

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• Models, collections...and then what? Processes?

  - by Dan

  I'm a LAMP-stack dev who's been more on the JavaScript side the last few years and really enjoying the Model + Collection approach to data entities that BackboneJS, etc. uses. It's helped me organize my code in such a way that it is extremely portable, keeping all my properties and methods in the scope (model, collection, etc.) in which they apply. One thing that keeps bugging me though is how to organize the next level up, the 'process layer' as you might call it, that can potentially operate on instances of either models or collections or whatever else. Where should methods like find() (which returns a collection) and create() (which returns a model) reside? I know some people would put a create() in the Collection prototype, but while a collection operates on models I don't think it's exactly right to create them. And while a find() would return a collection I don't think it correct to have that action within the collection prototype itself (it should be a layer up). Can anyone offer some examples of any patterns that employ some kind of OOP-friendly 'process' layer? I'm sorry if this is a fairly well-known discussion but I'm afraid I can't seem to find the terminology to search for.

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• Should I build a multi-threaded system that handles events from a game and sorts them, independently, into different threads based on priority?

  - by JonathonG

  Can I build a multi-threaded system that handles events from a game and sorts them, independently, into different threads based on priority, and is it a good idea? Here's more info: I am about to begin work on porting a mid-sized game from Flash/AS3 to Java so that I can continue development with multi-threading capabilities. Here's a small bit of background about the game: The game contains numerous asynchronous activities, such as "world updating" (the game environment is constantly changing based on a set of natural laws and forces), procedural generation of terrain, NPCs, quests, items, etc., and on top of that, the effects of all of the player's interactions with his environment are programmatically calculated in real time, based on a set of constantly changing "stats" and once again, natural laws and forces. All of these things going on at once, in an asynchronous manner, seem to lend themselves to multi-threading very well. My question is: Can I build some kind of central engine that handles the "stacking" of all of these events as they are triggered, and dynamically sorts them out amongst the available threads, and would it be a good idea? As an example: Essentially, every time something happens (IE, a magic missile being generated by a spell, or a bunch of plants need to grow to their next stage), instead of just processing that task right then and adding the new object(s) to a list of managed objects, send a reference to that event to a core "event handler" that throws it into a stack of all other currently queued events, which then sorts them out and orders them according to urgency, splits them between a number of available threads for as-fast-as-possible multithreaded execution.

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• Best way to load application settings

  - by enzom83

  A simple way to keep the settings of a Java application is represented by a text file with ".properties" extension containing the identifier of each setting associated with a specific value (this value may be a number, string, date, etc..). C# uses a similar approach, but the text file must be named "App.config". In both cases, in source code you must initialize a specific class for reading settings: this class has a method that returns the value (as string) associated with the specified setting identifier. // Java example Properties config = new Properties(); config.load(...); String valueStr = config.getProperty("listening-port"); // ... // C# example NameValueCollection setting = ConfigurationManager.AppSettings; string valueStr = setting["listening-port"]; // ... In both cases we should parse strings loaded from the configuration file and assign the ??converted values to the related typed objects (parsing errors could occur during this phase). After the parsing step, we must check that the setting values ??belong to a specific domain of validity: for example, the maximum size of a queue should be a positive value, some values ??may be related (example: min < max), and so on. Suppose that the application should load the settings as soon as it starts: in other words, the first operation performed by the application is to load the settings. Any invalid values for the settings ??must be replaced automatically with default values??: if this happens to a group of related settings, those settings are all set with default values. The easiest way to perform these operations is to create a method that first parses all the settings, then checks the loaded values ??and finally sets any default values??. However maintenance is difficult if you use this approach: as the number of settings increases while developing the application, it becomes increasingly difficult to update the code. In order to solve this problem, I had thought of using the Template Method pattern, as follows. public abstract class Setting { protected abstract bool TryParseValues(); protected abstract bool CheckValues(); public abstract void SetDefaultValues(); /// <summary> /// Template Method /// </summary> public bool TrySetValuesOrDefault() { if (!TryParseValues() || !CheckValues()) { // parsing error or domain error SetDefaultValues(); return false; } return true; } } public class RangeSetting : Setting { private string minStr, maxStr; private byte min, max; public RangeSetting(string minStr, maxStr) { this.minStr = minStr; this.maxStr = maxStr; } protected override bool TryParseValues() { return (byte.TryParse(minStr, out min) && byte.TryParse(maxStr, out max)); } protected override bool CheckValues() { return (0 < min && min < max); } public override void SetDefaultValues() { min = 5; max = 10; } } The problem is that in this way we need to create a new class for each setting, even for a single value. Are there other solutions to this kind of problem? In summary: Easy maintenance: for example, the addition of one or more parameters. Extensibility: a first version of the application could read a single configuration file, but later versions may give the possibility of a multi-user setup (admin sets up a basic configuration, users can set only certain settings, etc..). Object oriented design.

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• Do Java or C++ lack any OO features?

  - by tsv

  I am interested in understanding object-oriented programming in a more academic and abstract way than I currently do, and want to know if there are any object-oriented concepts Java and C++ fail to implement. I realise neither of the languages are "pure" OO, but I am interested in what (if anything) they lack, not what they have extra.

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• Performance issues when using SSD for a developer notebook (WAMP/LAMP stack)?

  - by András Szepesházi

  I'm a web application developer using my notebook as a standalone development environment (WAMP stack). I just switched from a Core2-duo Vista 32 bit notebook with 2Gb RAM and SATA HDD, to an i5-2520M Win7 64 bit with 4Gb RAM and 128 GB SDD (Corsair P3 128). My initial experience was what I expected, fast boot, quick load of all the applications (Eclipse takes now 5 seconds as opposed to 30s on my old notebook), overall great experience. Then I started to build up my development stack, both as LAMP (using VirtualBox with a debian guest) and WAMP (windows native apache + mysql + php). I wanted to compare those two. This still all worked great out, then I started to pull in my projects to these stacks. And here came the nasty surprise, one of those projects produced a lot worse response times than on my old notebook (that was true for both the VirtualBox and WAMP stack). Apache, php and mysql configurations were practically identical in all environments. I started to do a lot of benchmarking and profiling, and here is what I've found: All general benchmarks (Performance Test 7.0, HDTune Pro, wPrime2 and some more) gave a big advantage to the new notebook. Nothing surprising here. Disc specific tests showed that read/write operations peaked around 380M/160M for the SSD, and all the different sized block operations also performed very well. Started apache performance benchmarking with Apache Benchmark for a small static html file (10 concurrent threads, 500 iterations). Old notebook: min 47ms, median 111ms, max 156ms New WAMP stack: min 71ms, median 135ms, max 296ms New LAMP stack (in VirtualBox): min 6ms, median 46ms, max 175ms Right here I don't get why the native WAMP stack performed so bad, but at least the LAMP environment brought the expected speed. Apache performance measurement for non-cached php content. The php runs a loop of 1000 and generates sha1(uniqid()) inisde. Again, 10 concurrent threads, 500 iterations were used for the benchmark. Old notebook: min 0ms, median 39ms, max 218ms New WAMP stack: min 20ms, median 61ms, max 186ms New LAMP stack (in VirtualBox): min 124ms, median 704ms, max 2463ms What the hell? The new LAMP performed miserably, and even the new native WAMP was outperformed by the old notebook. php + mysql test. The test consists of connecting to a database and reading a single record form a table using INNER JOIN on 3 more (indexed) tables, repeated 100 times within a loop. Databases were identical. 10 concurrent threads, 100 iterations were used for the benchmark. Old notebook: min 1201ms, median 1734ms, max 3728ms New WAMP stack: min 367ms, median 675ms, max 1893ms New LAMP stack (in VirtualBox): min 1410ms, median 3659ms, max 5045ms And the same test with concurrency set to 1 (instead of 10): Old notebook: min 1201ms, median 1261ms, max 1357ms New WAMP stack: min 399ms, median 483ms, max 539ms New LAMP stack (in VirtualBox): min 285ms, median 348ms, max 444ms Strictly for my purposes, as I'm using a self contained development environment (= low concurrency) I could be satisfied with the second test's result. Though I have no idea why the VirtualBox environment performed so bad with higher concurrency. Finally I performed a test of including many php files. The application that I mentioned at the beginning, the one that was performing so bad, has a heavy bootstrap, loads hundreds of small library and configuration files while initializing. So this test does nothing else just includes about 100 files. Concurrency set to 1, 100 iterations: Old notebook: min 140ms, median 168ms, max 406ms New WAMP stack: min 434ms, median 488ms, max 604ms New LAMP stack (in VirtualBox): min 413ms, median 1040ms, max 1921ms Even if I consider that VirtualBox reached those files via shared folders, and that slows things down a bit, I still don't see how could the old notebook outperform so heavily both new configurations. And I think this is the real root of the slow performance, as the application uses even more includes, and the whole bootstrap will occur several times within a page request (for each ajax call, for example). To sum it up, here I am with a brand new high-performance notebook that loads the same page in 20 seconds, that my old notebook can do in 5-7 seconds. Needless to say, I'm not a very happy person right now. Why do you think I experience these poor performance values? What are my options to remedy this situation?

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• How do I prove or disprove "god" objects are wrong?

  - by honestduane

  Problem Summary: Long story short, I inherited a code base and an development team I am not allowed to replace and the use of God Objects is a big issue. Going forward, I want to have us re-factor things but I am getting push-back from the teams who want to do everything with God Objects "because its easier" and this means I would not be allowed to re-factor. I pushed back citing my years of dev experience, that I'm the new boss who was hired to know these things, etc, and so did the third party offshore companies account sales rep, and this is now at the executive level and my meeting is tomorrow and I want to go in with a lot of technical ammo to advocate best practices because I feel it will be cheaper in the long run (And I personally feel that is what the third party is worried about) for the company. My issue is from a technical level, I know its good long term but I'm having trouble with the ultra short term and 6 months term, and while its something I "know" I cant prove it with references and cited resources outside of one person (Robert C. Martin, aka Uncle Bob), as that is what I am being asked to do as I have been told having data from one person and only one person (Robert C Martin) is not good enough of an argument. Question: What are some resources I can cite directly (Title, year published, page number, quote) by well known experts in the field that explicitly say this use of "God" Objects/Classes/Systems is bad (or good, since we are looking for the most technically valid solution)? Research I have already done: I have a number of books here and I have searched their indexes for the use of the words "god object" and "god class". I found that oddly its almost never used and the copy of the GoF book I have for example, never uses it (At least according to the index in front of me) but I have found it in 2 books per the below, but I want more I can use. I checked the Wikipedia page for "God Object" and its currently a stub with little reference links so although I personally agree with that it says, It doesn't have much I can use in an environment where personal experience is not considered valid. The book cited is also considered too old to be valid by the people I am debating these technical points with as the argument they are making is that "it was once thought to be bad but nobody could prove it, and now modern software says "god" objects are good to use". I personally believe that this statement is incorrect, but I want to prove the truth, whatever it is. In Robert C Martin's "Agile Principles, Patterns, and Practices in C#" (ISBN: 0-13-185725-8, hardcover) where on page 266 it states "Everybody knows that god classes are a bad idea. We don't want to concentrate all the intelligence of a system into a single object or a single function. One of the goals of OOD is the partitioning and distribution of behavior into many classes and many function." -- And then goes on to say sometimes its better to use God Classes anyway sometimes (Citing micro-controllers as an example). In Robert C Martin's "Clean Code: A Handbook of Agile Software Craftsmanship" page 136 (And only this page) talks about the "God class" and calls it out as a prime example of a violation of the "classes should be small" rule he uses to promote the Single Responsibility Principle" starting on on page 138. The problem I have is all my references and citations come from the same person (Robert C. Martin), and am from the same single person/source. I am being told that because he is just one guy, my desire to not use "God Classes" is invalid and not accepted as a standard best practice in the software industry. Is this true? Am I doing things wrong from a technical perspective by trying to keep to the teaching of Uncle Bob? God Objects and Object Oriented Programming and Design: The more I think of this the more I think this is more something you learn when you study OOP and its never explicitly called out; Its implicit to good design is my thinking (Feel free to correct me, please, as I want to learn), The problem is I "know" this, but but not everybody does, so in this case its not considered a valid argument because I am effectively calling it out as universal truth when in fact most people are statistically ignorant of it since statistically most people are not programmers. Conclusion: I am at a loss on what to search for to get the best additional results to cite, since they are making a technical claim and I want to know the truth and be able to prove it with citations like a real engineer/scientist, even if I am biased against god objects due to my personal experience with code that used them. Any assistance or citations would be deeply appreciated.

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• Design pattern to handle queries using multiple models

  - by coderkane

  I am presented with a dilemma while trying to re-designing the class structure for my PHP/MySQL application to make it more elegant and conform it to the SOLID principle. The problem goes like this: Let as assume, there is an abstract class called person which has certain properties to define a generic person, such as name, age, date of birth etc. There are two classes, student, and teacher, that implements this abstract class. They add their own unique properties to it. I have designed all the three classes to include all the operational logic (details of which are not relevant in context of the question). Now, I need to create views/reports/data grids which contain details from multiple classes, for example, say, a list of all students doing projects in Chemistry mentored by a teacher whose name is the parameter to the query. This is just one example of a view, there are many different views in the application, which uses data from 3-4 tables, and each of them have multiple input parameters to generate them. Considering this particular example, I have written the relevant query using JOIN and the results are as expected and proper, now here is the dilemma: Keeping in mind the single responsibility principle, where should I keep this query? It does not belong to either Student class, or Teacher class or any other classes currently present. a) Should I create a new class, say dataView class, and design it as a MVC pattern and keep the query there? What about the other views? how do they fit in this architecture? b) Should I not keep the query in code at all, and make it DB View ? c) Am I completely wrong in the approach? If so what is the right approach? My considerations are as follows: a) should be easy to add new views later on if requirement comes, without having to copy-paste-modify code b) would like to make it as loosely coupled as possible so that if minor db structure changes happen, it does not break I did google searches on report design and OOP report generators, but all the result seem to focus on the visual design of the report rather than fetching the data. I have already taken care of the visual aspect of the report using MVC with html templates. I am sure this is a very fundamental problem with known solution, but I am somehow not able to find it (maybe searching with wrong keyword). Edit1: Modified the title to make it more relevant Edit2: The accepted answer got me thinking in the right direction and identify my design flaws, which eventually led me to find this question and the solution in Stack Overflow which gave me the detailed answer to clear the confusion.

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• Avoiding coupling

  - by Seralize

  It is also true that a system may become so coupled, where each class is dependent on other classes that depend on other classes, that it is no longer possible to make a change in one place without having a ripple effect and having to make subsequent changes in many places.[1] This is why using an interface or an abstract class can be valuable in any object-oriented software project. Quote from Wikipedia Starting from scratch I'm starting from scratch with a project that I recently finished because I found the code to be too tightly coupled and hard to refactor, even when using MVC. I will be using MVC on my new project aswell but want to try and avoid the pitfalls this time, hopefully with your help. Project summary My issue is that I really wish to keep the Controller as clean as possible, but it seems like I can't do this. The basic idea of the program is that the user picks wordlists which is sent to the game engine. It will pick random words from the lists until there are none left. Problem at hand My main problem is that the game will have 'modes', and need to check the input in different ways through a method called checkWord(), but exactly where to put this and how to abstract it properly is a challenge to me. I'm new to design patterns, so not sure whether there exist any might fit my problem. My own attempt at abstraction Here is what I've gotten so far after hours of 'refactoring' the design plans, and I know it's long, but it's the best I could do to try and give you an overview (Note: As this is the sketch, anything is subject to change, all help and advice is very welcome. Also note the marked coupling points): Wordlist class Wordlist { // Basic CRUD etc. here! // Other sample methods: public function wordlistCount($user_id) {} // Returns count of how many wordlists a user has public function getAll($user_id) {} // Returns all wordlists of a user } Word class Word { // Basic CRUD etc. here! // Other sample methods: public function wordCount($wordlist_id) {} // Returns count of words in a wordlist public function getAll($wordlist_id) {} // Returns all words from a wordlist public function getWordInfo($word_id) {} // Returns information about a word } Wordpicker class Wordpicker { // The class needs to know which words and wordlists to exclude protected $_used_words = array(); protected $_used_wordlists = array(); // Wordlists to pick words from protected $_wordlists = array(); /* Public Methods */ public function setWordlists($wordlists = array()) {} public function setUsedWords($used_words = array()) {} public function setUsedWordlists($used_wordlists = array()) {} public function getRandomWord() {} // COUPLING POINT! Will most likely need to communicate with both the Wordlist and Word classes /* Protected Methods */ protected function _checkAvailableWordlists() {} // COUPLING POINT! Might need to check if wordlists are deleted etc. protected function _checkAvailableWords() {} // COUPLING POINT! Method needs to get all words in a wordlist from the Word class } Game class Game { protected $_session_id; // The ID of a game session which gets stored in the database along with game details protected $_game_info = array(); // Game instantiation public function __construct($user_id) { if (! $this->_session_id = $this->_gameExists($user_id)) { // New game } else { // Resume game } } // This is the method I tried to make flexible by using abstract classes etc. // Does it even belong in this class at all? public function checkWord($answer, $native_word, $translation) {} // This method checks the answer against the native word / translation word, depending on game mode public function getGameInfo() {} // Returns information about a game session, or creates it if it does not exist public function deleteSession($session_id) {} // Deletes a game session from the database // Methods dealing with game session information protected function _gameExists($user_id) {} protected function _getProgress($session_id) {} protected function _updateProgress($game_info = array()) {} } The Game /* CONTROLLER */ /* "Guess the word" page */ // User input $game_type = $_POST['game_type']; // Chosen with radio buttons etc. $wordlists = $_POST['wordlists']; // Chosen with checkboxes etc. // Starts a new game or resumes one from the database $game = new Game($_SESSION['user_id']); $game_info = $game->getGameInfo(); // Instantiates a new Wordpicker $wordpicker = new Wordpicker(); $wordpicker->setWordlists((isset($game_info['wordlists'])) ? $game_info['wordlists'] : $wordlists); $wordpicker->setUsedWordlists((isset($game_info['used_wordlists'])) ? $game_info['used_wordlists'] : NULL); $wordpicker->setUsedWords((isset($game_info['used_words'])) ? $game_info['used_words'] : NULL); // Fetches an available word if (! $word_id = $wordpicker->getRandomWord()) { // No more words left - game over! $game->deleteSession($game_info['id']); redirect(); } else { // Presents word details to the user $word = new Word(); $word_info = $word->getWordInfo($word_id); } The Bit to Finish /* CONTROLLER */ /* "Check the answer" page */ // ?????????????????? ( http://pastebin.com/cc6MtLTR ) Make sure you toggle the 'Layout Width' to the right for a better view. Thanks in advance. Questions To which extent should objects be loosely coupled? If object A needs info from object B, how is it supposed to get this without losing too much cohesion? As suggested in the comments, models should hold all business logic. However, as objects should be independent, where to glue them together? Should the model contain some sort of "index" or "client" area which connects the dots? Edit: So basically what I should do for a start is to make a new model which I can more easily call with oneliners such as $model->doAction(); // Lots of code in here which uses classes! How about the method for checking words? Should it be it's own object? I'm not sure where I should put it as it's pretty much part of the 'game'. But on another hand, I could just leave out the 'abstraction and OOPness' and make it a method of the 'client model' which will be encapsulated from the controller anyway. Very unsure about this.

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• Stack Overflow problem in a recursive program in C

  - by Adi

  Hi all, I am getting a stack overflow in one of the recursive functions i am running.. Here is the code.. void* buddyMalloc(int req_size) { // Do something here return buddy_findout(original_index,req_size); // This is the recursive call } void *buddy_findout(int current_index,int req_size) { char *selected = NULL; if(front!=NULL) { if(current_index==original_index) { // Do something here return selected; } else { // Do Something here return buddy_findout(current_index+1,req_size); } } else { return buddy_findout(current_index-1,req_size); } } Consider the initial value of index to be 4. and it first do index-1 till it reaches 0 index. and then it comes back to index 4 by incrementing..This is wht i want to implement. But it gives a stack overflow with memory map in the command prompt : Here is the output from my shell : * glibc detected * ./473_mem: free(): invalid pointer: 0x00c274c0 * ======= Backtrace: ========= /lib/tls/i686/cmov/libc.so.6[0xb50ff1] /lib/tls/i686/cmov/libc.so.6[0xb526f2] /lib/tls/i686/cmov/libc.so.6(cfree+0x6d)[0xb557cd] ./473_mem[0x8048b44] ./473_mem[0x8048b74] ./473_mem[0x8048b74] ./473_mem[0x8048944] ./473_mem[0x8048c87] ./473_mem[0x8048d31] ./473_mem[0x8048f79] /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe6)[0xafcb56] ./473_mem[0x8048671] ======= Memory map: ======== 0017c000-00198000 r-xp 00000000 08:01 5224 /lib/libgcc_s.so.1 00198000-00199000 r--p 0001b000 08:01 5224 /lib/libgcc_s.so.1 00199000-0019a000 rw-p 0001c000 08:01 5224 /lib/libgcc_s.so.1 00260000-00284000 r-xp 00000000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 00284000-00285000 r--p 00023000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 00285000-00286000 rw-p 00024000 08:01 1927 /lib/tls/i686/cmov/libm-2.10.1.so 006cd000-006e8000 r-xp 00000000 08:01 6662 /lib/ld-2.10.1.so 006e8000-006e9000 r--p 0001a000 08:01 6662 /lib/ld-2.10.1.so 006e9000-006ea000 rw-p 0001b000 08:01 6662 /lib/ld-2.10.1.so 00aa9000-00aaa000 r-xp 00000000 00:00 0 [vdso] 00ae6000-00c24000 r-xp 00000000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c24000-00c25000 ---p 0013e000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c25000-00c27000 r--p 0013e000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c27000-00c28000 rw-p 00140000 08:01 1900 /lib/tls/i686/cmov/libc-2.10.1.so 00c28000-00c2b000 rw-p 00000000 00:00 0 08048000-0804a000 r-xp 00000000 00:14 2176 /media/windows-share/OS/Project2/473_mem 0804a000-0804b000 r--p 00001000 00:14 2176 /media/windows-share/OS/Project2/473_mem 0804b000-0804c000 rw-p 00002000 00:14 2176 /media/windows-share/OS/Project2/473_mem 08483000-084a4000 rw-p 00000000 00:00 0 [heap] b7600000-b7621000 rw-p 00000000 00:00 0 b7621000-b7700000 ---p 00000000 00:00 0 b7716000-b7819000 rw-p 00000000 00:00 0 b7827000-b782a000 rw-p 00000000 00:00 0 bfb96000-bfbab000 rw-p 00000000 00:00 0 [stack] Aborted Thanks in advance adi

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• Android - Calling getJSONArray throwing JSONException with no stack trace

  - by Agathron

  Hi all, I'm currently working on an android app that pulls a list of forums from a JSON feed. I'm trying to parse the feed and immediately upon calling getJSONArray a JSON exception is being thrown with no stack trace. The JSON being returned is stored in an JSONObject jobj with the format as follows: { "Forum": [ {"ForumName":"CEC Employee Communications Forum","ForumId":"105"}, {"ForumName":"CEC External Stakeholder Relations Forum","ForumId":"109"}, {"ForumName":"See All...","ForumId":"0"} ] } However when running the following code, I get an immediate exception without a stack trace: JSONArray jarray = new JSONArray(); jarray = jobj.getJSONArray("Forum"); Running jobj.GetJSONArray("Forum").toString(); returns what looks to be a correct array of the format: [ {"ForumName":"CEC Employee Communications Forum","ForumId":"105"}, {"ForumName":"CEC External Stakeholder Relations Forum","ForumId":"109"}, {"ForumName":"See All...","ForumId":"0"} ] I also tried JSONArray jarray = new JSONArray(jobj.GetJSONArray("Forum").toString()); and had the exception thrown immediately. Any help would be greatly appreciated. Thanks!

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• XCode 3.2.1 and Instruments: Useless Stack Trace

  - by Jason George

  I've reached the stage where it's time to start tracking down memory leaks and, to my dismay, Instruments is giving me very little to go on (other than the fact that I definitely have leaks). My stack trace contains no information other than memory addresses. Since I'm working on a new project and I've transitioned to version 3.2.1 of XCode in tandem, I'm not sure if it's my program configuration or XCode that's causing the problem. I have found one reference to the issue coupled with a post on the dyld leak that seems to be prevalent with the 3.2.1 release. Since I haven't been able to find much on the problem I'm guessing it's something I've created rather than a systematic issue with XCode. If someone has any idea where I might have thrown a wrench in the works, I would love some pointers. Also, if someone could just verify that the stack trace is indeed functioning properly in 3.2.1 that would be useful as well.

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• activities stack

  - by klaus-vlad

  Is there a way to vizualise the activity stack, at some moment during debug, or normal run ?

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• Ur mom is so fat

  - by FuckThisShit

  the recursive function to calculate her mass causes a stack overflow

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• Stack Allocation in C

  - by JT

  Is it bad style to design your simple C programs to allocate everything, or most everything, on the stack?

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• OpenID like Stack Overflow

  - by eWolf

  I want to create an OpenID login with PHP just like it can be found on Stack Overflow. I know there are many questions for this, but mine is different. If I understood it correctly, every OpenID is defined by a unique URL. But: If I hit the Google button on the Stack Overflow login page, one generic URL is inserted in the text field. Is this the direct URL to the OpenID server? And if it is, how do I have to pass the URL to this class?

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• How does a virtual machine work?

  - by Martin

  I've been looking into how programming languages work, and some of them have a so-called virtual machines. I understand that this is some form of emulation of the programming language within another programming language, and that it works like how a compiled language would be executed, with a stack. Did I get that right? With the proviso that I did, what bamboozles me is that many non-compiled languages allow variables with "liberal" type systems. In Python for example, I can write this: x = "Hello world!" x = 2**1000 Strings and big integers are completely unrelated and occupy different amounts of space in memory, so how can this code even be represented in a stack-based environment? What exactly happens here? Is x pointed to a new place on the stack and the old string data left unreferenced? Do these languages not use a stack? If not, how do they represent variables internally?

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• Assembly stack persistency

  - by user246100

  Hello. I would like to know if after calling functions the data I have in the stack is persistent. Like, I would like to know if (assuming cdecl convention) can I do this (independently of function X and independently of optimizations): push 1 push 2 push 3 call X call X call X add 12 esp ? Also, let's say that before the calls I save the address of where the pushed values are in a global variable. Can I, inside X, alter the values it contain by acessing the global variable? Like, for some reason I want that in X I'm able to alter the values in stack so that the second and third call to X receive different values.

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