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• getting a tiled image collection on the iPad (deepzoom)

  - by Chris B

  I have a set of tiled image collections created via microsoft's deep zoom composer, and a silverlight app that currently consumes them for display via MultiScaleImage - it's all working pretty well - I'd just like to get some experience with iPad programming and have a couple of ideas for some ipad applications. All my ideas rely on me being able to display/manipulate these tiled image sets (on the iPad). I just picked up a iMac to facilitate this. I'm not seeing any objective-c / cocoa-touch libraries for this though, so am assuming I will have to roll my own. (Saw the seadragon ajax component, which is pretty slick, but I'm dealing with collections here, which it doesn't support. I would also like to roll this as a native app just to get the experience). The only open source project I found for displaying/manipulating the tiled image sets was Openzoom -a flash component. I'm not to familiar with actionscript either (python, java, c#, and c are the only languages I have really used), but briefly inspecting the code I didn't really have any issues with it and can probably use it for hints on how to swap the tiles in and out, etc.. But, as I'm pretty new to obj-c/cocoa-touch, some pointers in the right direction would be appreciated. 1) Are there any other projects out there I am missing, or is openzoom my best bet for some reference? 2) Should I be trying to do this display in the UIKit framework, or should I do it as an OpenGL display? 3) Any other suggestions/pointers that I didn't think to ask.

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• Pointer Implementation Details in C

  - by Will Bickford

  I would like to know architectures which violate the assumptions I've listed below. Also I would like to know if any of the assumptions are false for all architectures (i.e. if any of them are just completely wrong). sizeof(int *) == sizeof(char *) == sizeof(void *) == sizeof(func_ptr *) The in-memory representation of all pointers for a given architecture is the same regardless of the data type pointed to. The in-memory representation of a pointer is the same as an integer of the same bit length as the architecture. Multiplication and division of pointer data types are only forbidden by the compiler. NOTE: Yes I know this is nonsensical. What I mean is - is there hardware support to forbid this incorrect usage? All pointer values can be casted to a single integer. In other words, what architectures still make use of segments and offsets? Incrementing a pointer is equivalent to adding sizeof(the pointed data type) to the memory address stored by the pointer. If p is an int32* then p+1 is equal to the memory address 4 bytes after p. I'm most used to pointers being used in a contiguous, virtual memory space. For that usage, I can generally get by thinking of them as addresses on a number line. See (http://stackoverflow.com/questions/1350471/pointer-comparison/1350488#1350488).

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• Design for a Debate club assignment application

  - by Amir Rachum

  Hi all, For my university's debate club, I was asked to create an application to assign debate sessions and I'm having some difficulties as to come up with a good design for it. I will do it in Java. Here's what's needed: What you need to know about BP debates: There are four teams of 2 debaters each and a judge. The four groups are assigned a specific position: gov1, gov2, op1, op2. There is no significance to the order within a team. The goal of the application is to get as input the debaters who are present (for example, if there are 20 people, we will hold 2 debates) and assign them to teams and roles with regards to the history of each debater so that: Each debater should debate with (be on the same team) as many people as possible. Each debater should uniformly debate in different positions. The debate should be fair - debaters have different levels of experience and this should be as even as possible - i.e., there shouldn't be a team of two very experienced debaters and a team of junior debaters. There should be an option for the user to restrict the assignment in various ways, such as: Specifying that two people should debate together, in a specific position or not. Specifying that a single debater should be in a specific position, regardless of the partner. etc... If anyone can try to give me some pointers for a design for this application, I'll be so thankful! Also, I've never implemented a GUI before, so I'd appreciate some pointers on that as well, but it's not the major issue right now.

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• C++ interpreter conceptual problem

  - by Jan Wilkins

  I've built an interpreter in C++ for a language created by me. One main problem in the design was that I had two different types in the language: number and string. So I have to pass around a struct like: class myInterpreterValue { myInterpreterType type; int intValue; string strValue; } Objects of this class are passed around million times a second during e.g.: a countdown loop in my language. Profiling pointed out: 85% of the performance is eaten by the allocation function of the string template. This is pretty clear to me: My interpreter has bad design and doesn't use pointers enough. Yet, I don't have an option: I can't use pointers in most cases as I just have to make copies. How to do something against this? Is a class like this a better idea? vector<string> strTable; vector<int> intTable; class myInterpreterValue { myInterpreterType type; int locationInTable; } So the class only knows what type it represents and the position in the table This however again has disadvantages: I'd have to add temporary values to the string/int vector table and then remove them again, this would eat a lot of performance again. Help, how do interpreters of languages like Python or Ruby do that? They somehow need a struct that represents a value in the language like something that can either be int or string.

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• Why i am getting NullPointerException for this btree method??

  - by user306540

  hi, i am writing code for btree algorithms. i am getting NullPointerException . why???? please somebody help me...! public void insertNonFull(BPlusNode root,BPlusNode parent,String key) { int i=0; BPlusNode child=new BPlusNode(); BPlusNode node=parent; while(true) { i=node.numKeys-1; if(node.leaf) { while(i>=0 && key.compareTo(node.keys[i])<0) { node.keys[i+1]=node.keys[i]; i--; } node.keys[i+1]=key; node.numKeys=node.numKeys+1; } else { while(i>=0 && key.compareTo(node.keys[i])<0) { i--; } } i++; child=node.pointers[i]; if(child!=null && child.numKeys==7) { splitChild(root,node,i,child); if(key.compareTo(node.keys[i])>0) { i++; } } node=node.pointers[i]; } }

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• C++ destructos causing crash's

  - by larsonator

  ok, so i got a some what intricate program that simulates the uni systems of students, units, and students enrolling in units. Students are stored in a binary search tree, Units are stored in a standard list. Student has a list of Unit Pointers, to store which units he/she is enrolled in Unit has a list of Student pointers, to store students which are enrolled in that unit. The unit collections (storing units in a list) as made as a static variable where the main function is, as is the Binary search tree of students. when its finaly time to close the program, i call the destructors of each. but at some stage, during the destructors on the unit side, Unhandled exception at 0x002e4200 in ClassAllocation.exe: 0xC0000005: Access violation reading location 0x00000000. UnitCollection destructor: UnitCol::~UnitCol() { list<Unit>::iterator itr; for(itr = UnitCollection.begin(); itr != UnitCollection.end();) { UnitCollection.pop_front(); itr = UnitCollection.begin(); } } Unit Destructor Unit::~Unit() { } now i got the same sorta problem on the student side of things BST destructors void StudentCol::Destructor(const BTreeNode * r) { if(r!= 0) { Destructor(r->getLChild()); Destructor(r->getRChild()); delete r; } } StudentCol::~StudentCol() { Destructor(root); } Student Destructor Student::~Student() { } so yeah any help would be greatly appreciated

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• NES Programming - Nametables?

  - by Jeffrey Kern

  Hello everyone, I'm wondering about how the NES displays its graphical muscle. I've researched stuff online and read through it, but I'm wondering about one last thing: Nametables. Basically, from what I've read, each 8x8 block in a NES nametable points to a location in the pattern table, which holds graphic memory. In addition, the nametable also has an attribute table which sets a certain color palette for each 16x16 block. They're linked up together like this: (assuming 16 8x8 blocks) Nametable, with A B C D = pointers to sprite data: ABBB CDCC DDDD DDDD Attribute table, with 1 2 3 = pointers to color palette data, with < referencing value to the left, ^ above, and ' to the left and above: 1<2< ^'^' 3<3< ^'^' So, in the example above, the blocks would be colored as so 1A 1B 2B 2B 1C 1D 2C 2C 3D 3D 3D 3D 3D 3D 3D 3D Now, if I have this on a fixed screen - it works great! Because the NES resolution is 256x240 pixels. Now, how do these tables get adjusted for scrolling? Because Nametable 0 can scroll into Nametable 1, and if you keep scrolling Nametable 0 will wrap around again. That I get. But what I don't get is how to scroll the attribute table wraps around as well. From what I've read online, the 16x16 blocks it assigns attributes for will cause color distortions on the edge tiles of the screen (as seen when you scroll left to right and vice-versa in SMB3). The concern I have is that I understand how to scroll the nametables, but how do you scroll the attribute table? For intsance, if I have a green block on the left side of the screen, moving the screen to right should in theory cause the tiles to the right to be green as well until they move more into frame, to which they'll revert to their normal colors.

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• Getting started with open source

  - by lola

  Hi all, I'm an undergraduate who has decided that he wants to join the open source community and contribute. However, I have come to think that, once you have chosen an open source project, a lot of time is spent in learning the nitty gritties of that project in addition to stuff like subversion,etc which a typical undergraduate isn't exposed to. So, you have to stick with that project for a long time, say a year or two, before moving on to other projects. In this case, choosing the right(for you) initial project is very important since if you choose one,and say, the development in your field of interest(in that project) is a low priority and not exciting enough, you'll lose interest and stop contributing to open source all together. So what I wanted to know was, since there are thousands of open source projects, is all this being documented somewhere with tags,etc so that a beginner can choose his projects. The GSoc 2010 ideas list is a great starting point, but it only covers a handful. Hence, I thought why not ask this at stackoverflow: if you have any pointers as to where to start, when choosing a FOSS project or any other tips related to starting with FOSS. P.S. I'm interested in projects involving mobile ad hoc networks(those using TinyOS, preferably), so pointers related to these will be great. I'm looking through Freifunk and OLPC as of now, needed more ideas.

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• forcing stack w/i 32bit when -m64 -mcmodel=small

  - by chaosless

  have C sources that must compile in 32bit and 64bit for multiple platforms. structure that takes the address of a buffer - need to fit address in a 32bit value. obviously where possible these structures will use natural sized void * or char * pointers. however for some parts an api specifies the size of these pointers as 32bit. on x86_64 linux with -m64 -mcmodel=small tboth static data and malloc()'d data fit within the 2Gb range. data on the stack, however, still starts in high memory. so given a small utility _to_32() such as: int _to_32( long l ) { int i = l & 0xffffffff; assert( i == l ); return i; } then: char *cp = malloc( 100 ); int a = _to_32( cp ); will work reliably, as would: static char buff[ 100 ]; int a = _to_32( buff ); but: char buff[ 100 ]; int a = _to_32( buff ); will fail the assert(). anyone have a solution for this without writing custom linker scripts? or any ideas how to arrange the linker section for stack data, would appear it is being put in this section in the linker script: .lbss : { *(.dynlbss) *(.lbss .lbss.* .gnu.linkonce.lb.*) *(LARGE_COMMON) } thanks!

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• C++ destructors causing crash's

  - by larsonator

  ok, so i got a some what intricate program that simulates the uni systems of students, units, and students enrolling in units. Students are stored in a binary search tree, Units are stored in a standard list. Student has a list of Unit Pointers, to store which units he/she is enrolled in Unit has a list of Student pointers, to store students which are enrolled in that unit. The unit collections (storing units in a list) as made as a static variable where the main function is, as is the Binary search tree of students. when its finaly time to close the program, i call the destructors of each. but at some stage, during the destructors on the unit side, Unhandled exception at 0x002e4200 in ClassAllocation.exe: 0xC0000005: Access violation reading location 0x00000000. UnitCollection destructor: UnitCol::~UnitCol() { list<Unit>::iterator itr; for(itr = UnitCollection.begin(); itr != UnitCollection.end();) { UnitCollection.pop_front(); itr = UnitCollection.begin(); } } Unit Destructor Unit::~Unit() { } now i got the same sorta problem on the student side of things BST destructors void StudentCol::Destructor(const BTreeNode * r) { if(r!= 0) { Destructor(r->getLChild()); Destructor(r->getRChild()); delete r; } } StudentCol::~StudentCol() { Destructor(root); } Student Destructor Student::~Student() { } so yeah any help would be greatly appreciated

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• C#. How to pass message from unsafe callback to managed code?

  - by maxima120

  Is there a simple example of how to pass messages from unsafe callback to managed code? I have a proprietary dll which receives some messages packed in structs and all is coming to a callback function. The example of usage is as follows but it calls unsafe code too. I want to pass the messages into my application which is all managed code. *P.S. I have no experience in interop or unsafe code. I used to develop in C++ 8 yrs ago but remember very little from that nightmarish times :) P.P.S. The application is loaded as hell, the original devs claim it processes 2mil messages per sec.. I need a most efficient solution.* static unsafe int OnCoreCallback(IntPtr pSys, IntPtr pMsg) { // Alias structure pointers to the pointers passed in. CoreSystem* pCoreSys = (CoreSystem*)pSys; CoreMessage* pCoreMsg = (CoreMessage*)pMsg; // message handler function. if (pCoreMsg->MessageType == Core.MSG_STATUS) OnCoreStatus(pCoreSys, pCoreMsg); // Continue running return (int)Core.CALLBACKRETURN_CONTINUE; } Thank you.

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• C callback functions defined in an unnamed namespace?

  - by Johannes Schaub - litb

  Hi all. I have a C++ project that uses a C bison parser. The C parser uses a struct of function pointers to call functions that create proper AST nodes when productions are reduced by bison: typedef void Node; struct Actions { Node *(*newIntLit)(int val); Node *(*newAsgnExpr)(Node *left, Node *right); /* ... */ }; Now, in the C++ part of the project, i fill those pointers class AstNode { /* ... */ }; class IntLit : public AstNode { /* ... */ }; extern "C" { Node *newIntLit(int val) { return (Node*)new IntLit(val); } /* ... */ } Actions createActions() { Actions a; a.newIntLit = &newIntLit; /* ... */ return a; } Now the only reason i put them within extern "C" is because i want them to have C calling conventions. But optimally, i would like their names still be mangled. They are never called by-name from C code, so name mangling isn't an issue. Having them mangled will avoid name conflicts, since some actions are called like error, and the C++ callback function has ugly names like the following just to avoid name clashes with other modules. extern "C" { void uglyNameError(char const *str) { /* ... */ } /* ... */ } a.error = &uglyNameError; I wondered whether it could be possible by merely giving the function type C linkage extern "C" void fty(char const *str); namespace { fty error; /* Declared! But i can i define it with that type!? */ } Any ideas? I'm looking for Standard-C++ solutions.

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• Dealing with array of IntPtr

  - by Padu Merloti

  I think I'm close and I bet the solution is something stupid. I have a C++ native DLL where I define the following function: DllExport bool __stdcall Open(const char* filePath, int *numFrames, void** data); { //creates the list of arrays here... don't worry, lifetime is managed somewhere else //foreach item of the list: { BYTE* pByte = GetArray(i); //here's where my problem lives *(data + i * sizeofarray) = pByte; } *numFrames = total number of items in the list return true; } Basically, given a file path, this function creates a list of byte arrays (BYTE*) and should return a list of pointers via the data param. Each pointing to a different byte array. I want to pass an array of IntPtr from C# and be able to marshal each individual array in order. Here's the code I'm using: [DllImport("mydll.dll",EntryPoint = "Open")] private static extern bool MyOpen( string filePath, out int numFrames, out IntPtr[] ptr); internal static bool Open( string filePath, out int numFrames, out Bitmap[] images) { var ptrList = new IntPtr[512]; MyOpen(filePath, out numFrames, out ptrList); images = new Bitmap[numFrames]; var len = 100; //for sake of simplicity for (int i=0; i<numFrames;i++) { var buffer = new byte[len]; Marshal.Copy(ptrList[i], buffer, 0, len); images[i] = CreateBitmapFromBuffer(buffer, height, width); } return true; } Problem is in my C++ code. When I assign *(data + i * sizeofarray) = pByte; it corrupts the array of pointers... what am I doing wrong?

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• How are two-dimensional arrays formatted in memory?

  - by Chris Cooper

  In C, I know I can dynamically allocate a two-dimensional array on the heap using the following code: int** someNumbers = malloc(arrayRows*sizeof(int*)); for (i = 0; i < arrayRows; i++) { someNumbers[i] = malloc(arrayColumns*sizeof(int)); } Clearly, this actually creates a one-dimensional array of pointers to a bunch of separate one-dimensional arrays of integers, and "The System" can figure you what I mean when I ask for: someNumbers[4][2]; But when I statically declare a 2D array, as in the following line...: int someNumbers[ARRAY_ROWS][ARRAY_COLUMNS]; ...does a similar structure get created on the stack, or is it of another form completely? (i.e. is it a 1D array of pointers? If not, what is it, and how do references to it get figured out?) Also, when I said, "The System," what is actually responsible for figuring that out? The kernel? Or does the C compiler sort it out while compiling?

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• Automating Excel 2010 using F#

  - by Clive Norman

  I have been searching for a FAQ to tell me how to open a Excel Workbook/Worksheet and also how to Save the File once I have finished. I notice that in most FAQ and all the books I have purchased on F# one is show how to create a new Workbook/Worksheet but is never shown how to either open or Save it. Being a newbie to F# I would very much appreciate it if anyone could kindly provide me with either an answer or perhaps a few pointers? Update As for why F# and not C# or VB? I am pleased to say that inspite of being a newbie (with the exception of Forth, VBA & Excel 2003, 2007 & 2010 and Visual Basic) I can do this in both VB, VBA & C# and since I've been retired on medical grounds, with plenty of time unfortunately on my hands, I like to continually set myself challenges to keep my little grey cells active and being a sucker for trying new languages....well! F# is now an intergral part of Visual Studio 2010 so I thought - why not. Consider this - if we are not willing to use or at least try a new languages - I would always be wonder if I might have prefer it to VBA, VB, C# ..... and if you look at it from another point of view, if no one is going to use it - why create it in the first place? I suppose you can say if cave men hadn't experimented and made fire by rubbing two sticks together - where would we be now and would matches have been invented? Although an complete answer would be good, I prefer a few pointers, to keep my challenge going. And lastly but not least - thank you for taking the trouble to respond!

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• C++ Memory Leak, Can't find where

  - by Nicholas

  I'm using Visual Studio 2008, Developing an OpenGL window. I've created several classes for creating a skeleton, one for joints, one for skin, one for a Body(which is a holder for several joints and skin) and one for reading a skel/skin file. Within each of my classes, I'm using pointers for most of my data, most of which are declared using = new int[XX]. I have a destructor for each Class that deletes the pointers, using delete[XX]. Within my GLUT display function I have it declaring a body, opening the files and drawing them, then deleting the body at the end of the display. But there's still a memory leak somewhere in the program. As Time goes on, it's memory usage just keep increasing, at a consistent rate, which I'm interpreting as something that's not getting deleted. I'm not sure if it's something in the glut display function that's just not deleting the Body class, or something else. I've followed the steps for memory leak detection in Visual Studio 2008 and it doesn't report any leak, but I'm not 100% sure if it's working right for me. I'm not fluent in C++, so there maybe something I'm overlooking, can anyone see it?

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• Any utility to test expand C/C++ #define macros?

  - by Randy

  It seems I often spend way too much time trying to get a #define macro to do exactly what i want. I'll post my current delemia below and any help is appreciated. But really the bigger question is whether there is any utility someone could reccomend, to quickly display what a macro is actually doing? It seems like even the slow trial and error process would go much faster if I could see what is wrong. Currently, I'm dynamically loading a long list of functions from a DLL I made. The way I've set things up, the function pointers have the same nanes as the exported functions, and the typedef(s) used to prototyp them have the same names, but with a prepended underscor. So I want to use a define to simplfy assignments of a long long list of function pointers. For example, In the code statement below, 'hexdump' is the name of a typdef'd function point, and is also the name of the function, while _hexdump is the name of the typedef. If GetProcAddress() fails, a failure counter in incremented. if (!(hexdump = (_hexdump)GetProcAddress(h, "hexdump"))) --iFail; So lets say I'd like to rplace each line like the above with a macro, like this... GETADDR_FOR(hexdump ) Well this is the best I've come up with so far. It doesn't work (my // comment is just to prevent text formatting in the message)... // #define GETADDR_FOR(a) if (!(a = (#_#a)GetProcAddress(h, "/""#a"/""))) --iFail; And again, while I'd APPRECIATE an insight into what silly mistake I've made, it would make my day to have a utility that would show me the error of my ways, by simply plugging in my macro

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• in c# ,one array of class and two connected instance of it why ?

  - by Al0NE

  Hi I wrote the code below : 1. MyClass[] origArr=new MyClass[3]; 2. MyClass[] arr1; 3. // filled the array with objects and did some work on it . 4. dgv_1.DataSource=origArr; 5. 6. // Here is the problem : 7. arr1=origArr; 8. // do some work on arr1 ... 9. dgv_2.DataSource=arr1; For some reason the data in 'origArr' changed when data in 'arr1' change ... I thought that maybe this happened because 'origArr' and 'arr1' are pointers referring to the same object so I changed line '7' to : 7. origArr.CopyTo(arr1,0); but it didn't work ... what can i do to make the pointers referring to different objects?

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• C++ Storing variables and inheritance

  - by Kaa

  Hello Everyone, Here is my situation: I have an event driven system, where all my handlers are derived from IHandler class, and implement an onEvent(const Event &event) method. Now, Event is a base class for all events and contains only the enumerated event type. All actual events are derived from it, including the EventKey event, which has 2 fields: (uchar) keyCode and (bool)isDown. Here's the interesting part: I generate an EventKey event using the following syntax: Event evt = EventKey(15, true); and I ship it to the handlers: EventDispatch::sendEvent(evt); // void EventDispatch::sendEvent(const Event &event); (EventDispatch contains a linked list of IHandlers and calls their onEvent(const Event &event) method with the parameter containing the sent event. Now the actual question: Say I want my handlers to poll the events in a queue of type Event, how do I do that? x Dynamic pointers with reference counting sound like too big of a solution. x Making copies is more difficult than it sounds, since I'm only receiving a reference to a base type, therefore each time I would need to check the type of event, upcast to EventKey and then make a copy to store in a queue. Sounds like the only solution - but is unpleasant since I would need to know every single type of event and would have to check that for every event received - sounds like a bad plan. x I could allocate the events dynamically and then send around pointers to those events, enqueue them in the array if wanted - but other than having reference counting - how would I be able to keep track of that memory? Do you know any way to implement a very light reference counter that wouldn't interfere with the user? What do you think would be a good solution to this design? I thank everyone in advance for your time. Sincerely, Kaa

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• Toolbar to modify displayed html/content in IE / Firefox / Chrome.

  - by JP

  Hi, I want to create toolbar, whose functionality would be: Whenever the toolbar is "On/Activated", all pages should be parsed by a function, and the modified html should be displayed. [Example: i) There was this skype toolbar that would recognize phone-numbers in pages and automatically add skype links ii) If you have used MacAfee / Alexa toolbars, they modify the search results page displayed by Google My functionality would a lot simpler though] I want to create this for all browsers (though answers/pointers to any one platform would be appreciated). Please note that I am new to toolbar development, so detailed pointers from basics would be very helpful. I have heard to GreaseMonkey. However, if I can do it in a more "basic" way, it would be very helpful. (Alternately, tips to make a "custom" toolbar using GreaseMonkey would be welcome - though I would like to do away with ability to add scripts, etc. Also I installed greasemonkey and it does show up as a toolbar in FF/IE at all! In IE, there is separate executable to add scripts - I want a standalone toolbar with ON/OFF facility in the browser). Thanks much! Regards, JP

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• What would the destructor for this class look like?

  - by cam

  class Equipment { std::vector<Armor*> vEquip; Weapon* mainWeapon; int totalDefense; int totalAttack; public: unsigned int GetWeight(); int * GetDefense(); bool EquipArmor(Armor* armor); bool UnequipArmor(Armor* armor); bool EquipWeapon(Weapon* wep); bool UnequipWeapon(Weapon* wep); Equipment(); virtual ~Equipment(); }; It seems like there should be no destructor. The vector of pointers will take care of itself when it goes out of scope, and the actual objects the pointers point to don't need to be deleted as there will be other references to it. All of the objects in this refer to the main Container: class Container { int weightLimit; unsigned int currWeight; std::vector<Item*> vItems; public: bool AddItem(Item* item); bool RemoveItem(Item* item); Container(); Container(int weightLim); Container(int weightLim, std::vector<Item*> items); ~Container(); }; Now here I can see it being necessary to delete all objects in the container, because this is where all the objects are assigned via AddItem(new Item("Blah")) (Armor and Weapon inherit from Item)

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• possible solutions of the warning

  - by lego69

  Hello, I have a very large code, that's why I can't post here all my code, can somebody explain what might be a problem if I have an error incompatible pointer type and give me several ways to solve it, thanks in advance just small clarification: I'm workin with pointers to functions ptrLine createBasicLine(){ DECLARE_RESULT_ALLOCATE_AND_CHECK(ptrLine, Line); result->callsHistory = listCreate(copyCall,destroyCall); <-here result->messagesHistory = listCreate(copyMessage,destroyMessage); <-and here result->linesFeature = NULL; result->strNumber = NULL; result->lastBill = 0; result->lineType = MTM_REGULAR_LINE; result->nCallTime = 0; result->nMessages = 0; result->rateForCalls = 0; result->rateForMessage = 0; return result; } copyCall,destroyCall - pointers to functions /** * Allocates a new List. The list starts empty. * * @param copyElement * Function pointer to be used for copying elements into the list or when * copying the list. * @param freeElement * Function pointer to be used for removing elements from the list * @return * NULL - if one of the parameters is NULL or allocations failed. * A new List in case of success. */ List listCreate(CopyListElement copyElement, FreeListElement freeElement); definitions of the functions ptrCall (*createCall)() = createNumberContainer; void (*destroyCall)(ptrCall) = destroyNumberContainer; ptrCall (*copyCall)(ptrCall) = copyNumberContainer;

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• List of values as keys for a Map

  - by thr

  I have lists of variable length where each item can be one of four unique, that I need to use as keys for another object in a map. Assume that each value can be either 0, 1, 2 or 3 (it's not integer in my real code, but a lot easier to explain this way) so a few examples of key lists could be: [1, 0, 2, 3] [3, 2, 1] [1, 0, 0, 1, 1, 3] [2, 3, 1, 1, 2] [1, 2] So, to re-iterate: each item in the list can be either 0, 1, 2 or 3 and there can be any number of items in a list. My first approach was to try to hash the contents of the array, using the built in GetHashCode() in .NET to combine the hash of each element. But since this would return an int I would have to deal with collisions manually (two equal int values are identical to a Dictionary). So my second approach was to use a quad tree, breaking down each item in the list into a Node that has four pointers (one for each possible value) to the next four possible values (with the root node representing [], an empty list), inserting [1, 0, 2] => Foo, [1, 3] => Bar and [1, 0] => Baz into this tree would look like this: Grey nodes nodes being unused pointers/nodes. Though I worry about the performance of this setup, but there will be no need to deal with hash collisions and the tree won't become to deep (there will mostly be lists with 2-6 items stored, rarely over 6). Is there some other magic way to store items with lists of values as keys that I have missed?

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• Windows 7 Phone Database – Querying with Views and Filters

  - by SeanMcAlinden

  I’ve just added a feature to Rapid Repository to greatly improve how the Windows 7 Phone Database is queried for performance (This is in the trunk not in Release V1.0). The main concept behind it is to create a View Model class which would have only the minimum data you need for a page. This View Model is then stored and retrieved rather than the whole list of entities. Another feature of the views is that they can be pre-filtered to even further improve performance when querying. You can download the source from the Microsoft Codeplex site http://rapidrepository.codeplex.com/. Setting up a view Lets say you have an entity that stores lots of data about a game result for example: GameScore entity public class GameScore : IRapidEntity {     public Guid Id { get; set; }     public string GamerId {get;set;}     public string Name { get; set; }     public Double Score { get; set; }     public Byte[] ThumbnailAvatar { get; set; }     public DateTime DateAdded { get; set; } }   On your page you want to display a list of scores but you only want to display the score and the date added, you create a View Model for displaying just those properties. GameScoreView public class GameScoreView : IRapidView {     public Guid Id { get; set; }     public Double Score { get; set; }     public DateTime DateAdded { get; set; } }   Now you have the view model, the first thing to do is set up the view at application start up. This is done using the following syntax. View Setup public MainPage() {     RapidRepository<GameScore>.AddView<GameScoreView>(x => new GameScoreView { DateAdded = x.DateAdded, Score = x.Score }); } As you can see, using a little bit of lambda syntax, you put in the code for constructing a single view, this is used internally for mapping an entity to a view. *Note* you do not need to map the Id property, this is done automatically, a view model id will always be the same as it’s corresponding entity.   Adding Filters One of the cool features of the view is that you can add filters to limit the amount of data stored in the view, this will dramatically improve performance. You can add multiple filters using the fluent syntax if required. In this example, lets say that you will only ever show the scores for the last 10 days, you could add a filter like the following: Add single filter public MainPage() {     RapidRepository<GameScore>.AddView<GameScoreView>(x => new GameScoreView { DateAdded = x.DateAdded, Score = x.Score })         .AddFilter(x => x.DateAdded > DateTime.Now.AddDays(-10)); } If you wanted to further limit the data, you could also say only scores above 100: Add multiple filters public MainPage() {     RapidRepository<GameScore>.AddView<GameScoreView>(x => new GameScoreView { DateAdded = x.DateAdded, Score = x.Score })         .AddFilter(x => x.DateAdded > DateTime.Now.AddDays(-10))         .AddFilter(x => x.Score > 100); }   Querying the view model So the important part is how to query the data. This is done using the repository, there is a method called Query which accepts the type of view as a generic parameter (you can have multiple View Model types per entity type) You can either use the result of the query method directly or perform further querying on the result is required. Querying the View public void DisplayScores() {     RapidRepository<GameScore> repository = new RapidRepository<GameScore>();     List<GameScoreView> scores = repository.Query<GameScoreView>();       // display logic } Further Filtering public void TodaysScores() {     RapidRepository<GameScore> repository = new RapidRepository<GameScore>();     List<GameScoreView> todaysScores = repository.Query<GameScoreView>().Where(x => x.DateAdded > DateTime.Now.AddDays(-1)).ToList();       // display logic }   Retrieving the actual entity Retrieving the actual entity can be done easily by using the GetById method on the repository. Say for example you allow the user to click on a specific score to get further information, you can use the Id populated in the returned View Model GameScoreView and use it directly on the repository to retrieve the full entity. Get Full Entity public void GetFullEntity(Guid gameScoreViewId) {     RapidRepository<GameScore> repository = new RapidRepository<GameScore>();     GameScore fullEntity = repository.GetById(gameScoreViewId);       // display logic } Synchronising The View If you are upgrading from Rapid Repository V1.0 and are likely to have data in the repository already, you will need to perform a synchronisation to ensure the views and entities are fully in sync. You can either do this as a one off during the application upgrade or if you are a little more cautious, you could run this at each application start up. Synchronise the view public void MyUpgradeTasks() {     RapidRepository<GameScore>.SynchroniseView<GameScoreView>(); } It’s worth noting that in normal operation, the view keeps itself in sync with the entities so this is only really required if you are upgrading from V1.0 to V2.0 when it gets released shortly.   Summary I really hope you like this feature, it will be great for performance and I believe supports good practice by promoting the use of View Models for specific pages. I’m hoping to produce a beta for this over the next few days, I just want to add some more tests and hopefully iron out any bugs. I would really appreciate any thoughts on this feature and would really love to know of any bugs you find. You can download the source from the following : http://rapidrepository.codeplex.com/ Kind Regards, Sean McAlinden.

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• Hibernate unable to instantiate default tuplizer - cannot find getter

  - by ZeldaPinwheel

  I'm trying to use Hibernate to persist a class that looks like this: public class Item implements Serializable, Comparable<Item> { // Item id private Integer id; // Description of item in inventory private String description; // Number of items described by this inventory item private int count; //Category item belongs to private String category; // Date item was purchased private GregorianCalendar purchaseDate; public Item() { } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } public int getCount() { return count; } public void setCount(int count) { this.count = count; } public String getCategory() { return category; } public void setCategory(String category) { this.category = category; } public GregorianCalendar getPurchaseDate() { return purchaseDate; } public void setPurchasedate(GregorianCalendar purchaseDate) { this.purchaseDate = purchaseDate; } My Hibernate mapping file contains the following: <property name="puchaseDate" type="java.util.GregorianCalendar"> <column name="purchase_date"></column> </property> When I try to run, I get error messages indicating there is no getter function for the purchaseDate attribute: 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Using Hibernate built-in connection pool (not for production use!) 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Hibernate connection pool size: 20 577 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - autocommit mode: false 592 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost:3306/home_inventory 592 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - connection properties: {user=root, password=****} 1078 [main] INFO org.hibernate.cfg.SettingsFactory - RDBMS: MySQL, version: 5.1.45 1078 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC driver: MySQL-AB JDBC Driver, version: mysql-connector-java-5.1.12 ( Revision: ${bzr.revision-id} ) 1103 [main] INFO org.hibernate.dialect.Dialect - Using dialect: org.hibernate.dialect.MySQLDialect 1107 [main] INFO org.hibernate.engine.jdbc.JdbcSupportLoader - Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4 1109 [main] INFO org.hibernate.transaction.TransactionFactoryFactory - Using default transaction strategy (direct JDBC transactions) 1110 [main] INFO org.hibernate.transaction.TransactionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended) 1110 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic flush during beforeCompletion(): disabled 1110 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic session close at end of transaction: disabled 1110 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch size: 15 1110 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch updates for versioned data: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Scrollable result sets: enabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC3 getGeneratedKeys(): enabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Connection release mode: auto 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Maximum outer join fetch depth: 2 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Default batch fetch size: 1 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Generate SQL with comments: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL updates by primary key: disabled 1111 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL inserts for batching: disabled 1112 [main] INFO org.hibernate.cfg.SettingsFactory - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory 1113 [main] INFO org.hibernate.hql.ast.ASTQueryTranslatorFactory - Using ASTQueryTranslatorFactory 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Query language substitutions: {} 1113 [main] INFO org.hibernate.cfg.SettingsFactory - JPA-QL strict compliance: disabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Second-level cache: enabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Query cache: disabled 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Cache region factory : org.hibernate.cache.impl.NoCachingRegionFactory 1113 [main] INFO org.hibernate.cfg.SettingsFactory - Optimize cache for minimal puts: disabled 1114 [main] INFO org.hibernate.cfg.SettingsFactory - Structured second-level cache entries: disabled 1117 [main] INFO org.hibernate.cfg.SettingsFactory - Echoing all SQL to stdout 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Statistics: disabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Deleted entity synthetic identifier rollback: disabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Default entity-mode: pojo 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Named query checking : enabled 1118 [main] INFO org.hibernate.cfg.SettingsFactory - Check Nullability in Core (should be disabled when Bean Validation is on): enabled 1151 [main] INFO org.hibernate.impl.SessionFactoryImpl - building session factory org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer] at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:110) at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:135) at org.hibernate.tuple.entity.EntityEntityModeToTuplizerMapping.<init>(EntityEntityModeToTuplizerMapping.java:80) at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:323) at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:475) at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:133) at org.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:84) at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:295) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1385) at service.HibernateSessionFactory.currentSession(HibernateSessionFactory.java:53) at service.ItemSvcHibImpl.generateReport(ItemSvcHibImpl.java:78) at service.test.ItemSvcTest.testGenerateReport(ItemSvcTest.java:226) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at junit.framework.TestCase.runTest(TestCase.java:164) at junit.framework.TestCase.runBare(TestCase.java:130) at junit.framework.TestResult$1.protect(TestResult.java:106) at junit.framework.TestResult.runProtected(TestResult.java:124) at junit.framework.TestResult.run(TestResult.java:109) at junit.framework.TestCase.run(TestCase.java:120) at junit.framework.TestSuite.runTest(TestSuite.java:230) at junit.framework.TestSuite.run(TestSuite.java:225) at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:107) ... 29 more Caused by: org.hibernate.PropertyNotFoundException: Could not find a getter for puchaseDate in class domain.Item at org.hibernate.property.BasicPropertyAccessor.createGetter(BasicPropertyAccessor.java:328) at org.hibernate.property.BasicPropertyAccessor.getGetter(BasicPropertyAccessor.java:321) at org.hibernate.mapping.Property.getGetter(Property.java:304) at org.hibernate.tuple.entity.PojoEntityTuplizer.buildPropertyGetter(PojoEntityTuplizer.java:299) at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:158) at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:77) ... 34 more I'm new to Hibernate, so I don't know all the ins and outs, but I do have the getter and setter for the purchaseDate attribute. I don't know what I'm missing here - does anyone else? Thanks!

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