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  • How to prevent linq-to-sql designer undo my changing

    - by anonim.developer
    Dear All, Thanks for your attention in advance, I’ve met an issue with LINQ-2-SQL designer in VS 2008 SP1 which has made me CRAZY. I use Linq2sql as my DAL. It seems Linq2sql speeds up coding in the first step but lots of issues arise in feature specifically with table or object inheritance. In this case I have a class Entity that all other entity classes generated by Linq2sql designer inherit from. public abstract class Entity { public virtual Guid ID { get; protected set; } } public partial class User : monius.Data.Entity { } And the following generated by L2S designer (DataModel.designer.cs) [Column(Storage = "_ID", AutoSync = AutoSync.OnInsert, DbType = "UniqueIdentifier NOT NULL", IsPrimaryKey = true, IsDbGenerated = true, UpdateCheck = UpdateCheck.Never)] [DataMember(Order = 1)] public System.Guid ID { get { return this._ID; } set { if ((this._ID != value)) { this.OnIDChanging(value); this.SendPropertyChanging(); this._ID = value; this.SendPropertyChanged("ID"); this.OnIDChanged(); } } } When I compile the code VS warns me that Warning 1 'User.ID' hides inherited member 'Entity.ID'. To make the current member override that mplementation, add the override keyword. Otherwise add the new keyword. That warning is obvious and I have to change the code generated by L2S designer (DataModel.designer.cs) to […] public override System.Guid ID { … protected set … } And the code compiled with no error or warning and everyone is happy. But that is not the end of story. As soon as I made changes to entities of the diagram (dbml) or even I open dbml file to view it, any change manually I made to designer has been vanished and POOF! Redo AGAIN. That is a painful job. Now I wonder if there is a way to force L2S designer not changing portions of auto-generated code. I’ll be appreciated if someone kindly helps me with this issue.

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  • Capturing time intervals when somebody was online? How would you impement this feature?

    - by Kirzilla
    Hello, Our aim is to build timelines saying about periods of time when user was online. (It really doesn't matter what user we are talking about and where he was online) To get information about onliners we can call API method, someservice.com/api/?call=whoIsOnline whoIsOnline method will give us a list of users currently online. But there is no API method to get information about who IS NOT online. So, we should build our timelines using information we got from whoIsOnline. Of course there will be a measurement error (we can't track information in realtime). Let's suppose that we will call whoIsOnline method every 2 minutes (yes, we will run our script by cron every 2 minutes). For example, calling whoIsOnline at 08:00 will return Peter_id Michal_id Andy_id calling whoIsOnline at 08:02 will return Michael_id Andy_id George_id As you can see, Peter has gone offline, but we have new onliner - George. Available instruments are Db(MySQL) / text files / key-value storage (Redis/memcache); feel free to choose any of them (or even all of them). So, we have to get information like this George_id was online... 12 May: 08:02-08:30, 12:40-12:46, 20:14-22:36 11 May: 09:10-12:30, 21:45-23:00 10 May: was not online And now question... How would you store information to implement such timelines? How would you query/calculate information about periods of time when user was online? Additional information.. You cannot update information about offline users, only users who are "currently" online. Solution should be flexible: timeline information could be represented relating to any timezone. We should keep information only for last 7 days. Every user seen online is automatically getting his own identifier in our database. Uff.. it was really hard for me to write it because my English is pretty bad, but I hope my question will be clear for you. Thank you.

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  • Is there a Boost (or other common lib) type for matrices with string keys?

    - by mohawkjohn
    I have a dense matrix where the indices correspond to genes. While gene identifiers are often integers, they are not contiguous integers. They could be strings instead, too. I suppose I could use a boost sparse matrix of some sort with integer keys, and it wouldn't matter if they're contiguous. Or would this still occupy a great deal of space, particularly if some genes have identifiers that are nine digits? Further, I am concerned that sparse storage is not appropriate, since this is an all-by-all matrix (there will be a distance in each and every cell, provided the gene exists). I'm unlikely to need to perform any matrix operations (e.g., matrix multiplication). I will need to pull vectors out of the matrix (slices). It seems like the best type of matrix would be keyed by a Boost unordered_map (a hash map), or perhaps even simply an STL map. Am I looking at this the wrong way? Do I really need to roll my own? I thought I saw such a class somewhere before. Thanks!

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  • Using ARIMA to model and forecast stock prices using user-friendly stats program

    - by Brian
    Hi people, Can anyone please offer some insight into this for me? I'm coming from a functional magnetic resonance imaging research background where I analyzed a lot of time series data, and I'd like to analyze the time series of stock prices (or returns) by: 1) modeling a successful stock in a particular market sector and then cross-correlating the time series of this historically successful stock with that of other newer stocks to look for significant relationships; 2) model a stock's price time series and use forecasting (e.g., exponential smoothing) to predict future values of it. I'd like to use non-linear modeling methods (ARIMA and ARCH) to do this. Several questions: How often do ARIMA and ARCH modeling methods (given that the individual who implements them does so accurately) actually fit the stock time series data they target, and what is the optimal fit I can expect? Is the extent to which this model fits the data commensurate with the extent to which it predicts this stock time series' future values? Rather than randomly selecting stocks to compare or model, if profit is my goal, what is an efficient approach, if any, to selecting the stocks I'm going to analyze? Which stats program is the most user-friendly for this? Any thoughts on this would be great and would go a long way for me. Thanks, Brian

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  • Getting Error When Opening Files

    - by Nathan Campos
    I'm developing a simple Text Editor to understand better PocketC language, then I've done this: #include "\\Storage Card\\My Documents\\PocketC\\Parrot\\defines.pc" int filehandle; int file_len; string file_mode; initComponents() { createctrl("EDIT", "test", 2, 1, 0, 24, 70, 25, TEXTBOX); wndshow(TEXTBOX, SW_SHOW); guigetfocus(); } main() { filehandle = fileopen(OpenFileDlg("Plain Text Files (*.txt)|*.txt; All Files (*.*)|*.*"), 0, FILE_READWRITE); file_len = filegetlen(filehandle); if(filehandle = -1) { MessageBox("File Could Not Be Found!", "Error", 3, 1); } initComponents(); editset(TEXTBOX, fileread(filehandle, file_len)); } Then I tried to run the application, it opens the Open File Dialog, I select a file(that is at \test.txt) that I've created with notepad, then I got my MessageBox saying that the file wans't found. Then I want to know why I'm getting this if the file is all correct? *PS: When I click to exit the MessageBox, I saw that the TextBox is displaying where the file is(I've tested with many other files, and with all I got the error and this).

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  • Python IOError: Not a gzipped file (Gzip and Blowfish Encrypt/Compress)

    - by notbad.jpeg
    I'm having some problems with python's built-in library gzip. Looked through almost every other stack question about it, and none of them seem to work. MY PROBLEM IS THAT WHEN I TRY TO DECOMPRESS I GET THE IOError I'm Getting: Traceback (most recent call last): File "mymodule.py", line 61, in return gz.read() File "/usr/lib/python2.7/gzip.py", line 245, readself._read(readsize) File "/usr/lib/python2.7/gzip.py", line 287, in _readself._read_gzip_header() File "/usr/lib/python2.7/gzip.py", line 181, in _read_gzip_header raise IOError, 'Not a gzipped file'IOError: Not a gzipped file This is my code to send it over SMB, it might not make sense why i do things, but it's normally in a while loop and memory efficient, I just simplified it. buffer = cStringIO.StringIO(output) #output is from a subprocess call small_buffer = cStringIO.StringIO() small_string = buffer.read() #need a string to write to buffer gzip_obj = gzip.GzipFile(fileobj=small_buffer,compresslevel=6, mode='wb') gzip_obj.write(small_string) compressed_str = small_buffer.getvalue() blowfish = Blowfish.new('abcd', Blowfish.MODE_ECB) remainder = '|'*(8 - (len(compressed_str) % 8)) compressed_str += remainder encrypted = blowfish.encrypt(compressed_str) #i send it over smb, then retrieve it later Then this is the code that retrieves it: #buffer is a cStringIO object filled with data from smb retrieval decrypter = Blowfish.new('abcd', Blowfish.MODE_ECB) value = buffer.getvalue() decrypted = decrypter.decrypt(value) buff = cStringIO.StringIO(decrypted) buff.seek(0) gz = gzip.GzipFile(fileobj=buff) return gz.read() Here's the problem return gz.read()

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  • jsTree: How to create a new ID for the new added node?

    - by marknt15
    Hi, I can normally get the ID of the default tree nodes but my problem is onCreate then jsTree will add a new node but it doesn't have an ID. My question is how can I add an ID to the newly created tree node? What I'm thinking to do is adding the ID HTML attribute to the newly created tree node but how? I need to get the ID of all of the nodes because it will serve as a reference for the node's respective div storage. HTML code: <div class="demo" id="demo_1"> <ul> <li id="phtml_1" class="file"><a href="#"><ins>&nbsp;</ins>Root node 1</a></li> <li id="phtml_2" class="file"><a href="#"><ins>&nbsp;</ins>Root node 2</a></li> </ul> </div> JS code: $("#demo_1").tree({ ui : { theme_name : "apple" }, callback : { onrename : function (NODE, TREE_OBJ) { alert(TREE_OBJ.get_text(NODE)); alert($(NODE).attr('id')); } } }); Cheers, Mark

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  • Database access through collections

    - by Mike
    Hi All, I have an 3 tiered application where I need to get database results and populated the UI. I have a MessagesCollection class that deals with messages. I load my user from the database. On the instantiation of a user (ie. new User()), a MessageCollection Messages = new MessageCollection(this) is performed. Message collection accepts a user as a parameter. User user = user.LoadUser("bob"); I want to get the messages for Bob. user.Messages.GetUnreadMessages(); GetUnreadMessages calls my Business Data provider which in turn calls the data access layer. The Business data provider returns List. My question is - I am not sure what the best practice is here - If I have a collection of messages in an array inside the MessagesCollection class, I could implement ICollection to provide GetEnumerator() and ability to traverse the messages. But what happens if the messages change and the the user has old messages loaded? What about big message collections? What if my user had 10,000 unread messages? I don't think accessing the database and returning 10,000 Message objects would be efficient.

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  • NSMutableObject from existing custom class

    - by A.S.
    Hello there. I have an existing class that has methods to deserialise from XML in my code. Now I need to create correct CoreData model from that class. It's objects will be created not only from CoreData storage but also by deserializing XML (somehow like instance->title = [[NSString stringWithUTF8String: (const char *)subNode->children->content] retain; ) without saving to CoreData, and sometimes I need to save it. What is the correct steps to modify existing class to do that except of adding CoreData framework and making my class an NSManagedObject instead of NSObject? Class sample: @interface TSTSong : NSManagedObject<NTSerializableObject> { NSString *identifier; NSString *title; float length; NSURL *previewURL; NSString *author; NSURL *coverURL; NSString *appStoreId; BOOL isPurchased; NSURL *bannerURL; NSDecimalNumber *priceValue; NSLocale *priceLocale; } P.S. I'm noob, so I'f I'm doing smth. wrong - please let me know. Sorry for my english.

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  • Get Last Friday of Month in Java

    - by Nick Klauer
    I am working on a project where the requirement is to have a date calculated as being the last Friday of a given month. I think I have a solution that only uses standard Java, but I was wondering if anyone knew of anything more concise or efficient. Below is what I tested with for this year: for (int month = 0; month < 13; month++) { GregorianCalendar d = new GregorianCalendar(); d.set(d.MONTH, month); System.out.println("Last Week of Month in " + d.getDisplayName(d.MONTH, Calendar.LONG, Locale.ENGLISH) + ": " + d.getLeastMaximum(d.WEEK_OF_MONTH)); d.set(d.DAY_OF_WEEK, d.FRIDAY); d.set(d.WEEK_OF_MONTH, d.getActualMaximum(d.WEEK_OF_MONTH)); while (d.get(d.MONTH) > month || d.get(d.MONTH) < month) { d.add(d.WEEK_OF_MONTH, -1); } Date dt = d.getTime(); System.out.println("Last Friday of Last Week in " + d.getDisplayName(d.MONTH, Calendar.LONG, Locale.ENGLISH) + ": " + dt.toString()); }

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  • Why is cell phone software is still so primitive?

    - by Tomislav Nakic-Alfirevic
    I don't do mobile development, but it strikes me as odd that features like this aren't available by default on most phones: full text search: searches all address book contents, messages, anything else being a plus better call management: e.g. a rotating audio call log, meaning you always have the last N calls recorded for your listening pleasure later (your little girl just said her first "da-da" while you were on a business trip, you had a telephone job interview, you received complex instructions to do something etc.) bluetooth remote control (like e.g. anyRemote, but available by default on a bluetooth phone) no multitasking capabilities worth mentioning and in general no e.g. weekly software updates, making the phone much more usable (even if it had to be done over USB, rather than over the network). I'm sure I was dumbfounded by the lack or design of other features as well, but they don't come to mind right now. To clarify, I'm not talking about smartphones here: my plain, 2-year old phone has a CPU an order of magnitude faster than my first PC, about as much storage space and it's ridiculous how bad (slow, unwieldy) the software is and it's not one phone or one manufacturer. What keeps the (to me) obvious software functionality vacuum on a capable hardware platform from being filled up?

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  • Calculating bounding box a certain distance away from a lat/long coordinate in Java

    - by Bryce Thomas
    Given a coordinate (lat, long), I am trying to calculate a square bounding box that is a given distance (e.g. 50km) away from the coordinate. So as input I have lat, long and distance and as output I would like two coordinates; one being the south-west (bottom-left) corner and one being the north-east (top-right) corner. I have seen a couple of answers on here that try to address this question in Python, but I am looking for a Java implementation in particular. Just to be clear, I intend on using the algorithm on Earth only and so I don't need to accommodate a variable radius. It doesn't have to be hugely accurate (+/-20% is fine) and it'll only be used to calculate bounding boxes over small distances (no more than 150km). So I'm happy to sacrifice some accuracy for an efficient algorithm. Any help is much appreciated. Edit: I should have been clearer, I really am after a square, not a circle. I understand that the distance between the center of a square and various points along the square's perimeter is not a constant value like it is with a circle. I guess what I mean is a square where if you draw a line from the center to any one of the four points on the perimeter that results in a line perpendicular to a side of the perimeter, then those 4 lines have the same length.

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  • If attacker has original data and encrypted data, can they determine the passphrase?

    - by Brad Cupit
    If an attacker has several distinct items (for example: e-mail addresses) and knows the encrypted value of each item, can the attacker more easily determine the secret passphrase used to encrypt those items? Meaning, can they determine the passphrase without resorting to brute force? This question may sound strange, so let me provide a use-case: User signs up to a site with their e-mail address Server sends that e-mail address a confirmation URL (for example: https://my.app.com/confirmEmailAddress/bill%40yahoo.com) Attacker can guess the confirmation URL and therefore can sign up with someone else's e-mail address, and 'confirm' it without ever having to sign in to that person's e-mail account and see the confirmation URL. This is a problem. Instead of sending the e-mail address plain text in the URL, we'll send it encrypted by a secret passphrase. (I know the attacker could still intercept the e-mail sent by the server, since e-mail are plain text, but bear with me here.) If an attacker then signs up with multiple free e-mail accounts and sees multiple URLs, each with the corresponding encrypted e-mail address, could the attacker more easily determine the passphrase used for encryption? Alternative Solution I could instead send a random number or one-way hash of their e-mail address (plus random salt). This eliminates storing the secret passphrase, but it means I need to store that random number/hash in the database. The original approach above does not require storage in the database. I'm leaning towards the the one-way-hash-stored-in-the-db, but I still would like to know the answer: does having multiple unencrypted e-mail addresses and their encrypted counterparts make it easier to determine the passphrase used?

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  • Reasons for & against a Database

    - by dbemerlin
    Hi, i had a discussion with a coworker about the architecture of a program i'm writing and i'd like some more opinions. The Situation: The Program should update at near-realtime (+/- 1 Minute). It involves the movement of objects on a coordinate system. There are some events that occur at regular intervals (i.e. creation of the objects). Movements can change at any time through user input. My solution was: Build a server that runs continously and stores the data internally. The server dumps a state-of-the-program at regular intervals to protect against powerfailures and/or crashes. He argued that the program requires a Database and i should use cronjobs to update the data. I can store movement information by storing startpoint, endpoint and speed and update the position in the cronjob (and calculate collisions with other objects there) by calculating direction and speed. His reasons: Requires more CPU & Memory because it runs constantly. Powerfailures/Crashes might destroy data. Databases are faster. My reasons against this are mostly: Not very precise as events can only occur at full minutes (wouldn't be that bad though). Requires (possibly costly) transformation of data on every run from relational data to objects. RDBMS are a general solution for a specialized problem so a specialized solution should be more efficient. Powerfailures (or other crashes) can leave the Data in an undefined state with only partially updated data unless (possibly costly) precautions (like transactions) are taken. What are your opinions about that? Which arguments can you add for any side?

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  • Embedded non-relational (nosql) data store

    - by Igor Brejc
    I'm thinking about using/implementing some kind of an embedded key-value (or document) store for my Windows desktop application. I want to be able to store various types of data (GPS tracks would be one example) and of course be able to query this data. The amount of data would be such that it couldn't all be loaded into memory at the same time. I'm thinking about using sqlite as a storage engine for a key-value store, something like y-serial, but written in .NET. I've also read about FriendFeed's usage of MySQL to store schema-less data, which is a good pointer on how to use RDBMS for non-relational data. sqlite seems to be a good option because of its simplicity, portability and library size. My question is whether there are any other options for an embedded non-relational store? It doesn't need to be distributable and it doesn't have to support transactions, but it does have to be accessible from .NET and it should have a small download size. UPDATE: I've found an article titled SQLite as a Key-Value Database which compares sqlite with Berkeley DB, which is an embedded key-value store library.

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  • FIFO dequeueing in python?

    - by Aaron Ramsey
    hello again everybody— I'm looking to make a functional (not necessarily optimally efficient, as I'm very new to programming) FIFO queue, and am having trouble with my dequeueing. My code looks like this: class QueueNode: def __init__(self, data): self.data = data self.next = None def __str__(self): return str(self.data) class Queue: def__init__(self): self.front = None self.rear = None self.size = 0 def enqueue(self, item) newnode = QueueNode(item) newnode.next = None if self.size == 0: self.front = self.rear = newnode else: self.rear = newnode self.rear.next = newnode.next self.size = self.size+1 def dequeue(self) dequeued = self.front.data del self.front self.size = self.size-1 if self.size == 0: self.rear = None print self.front #for testing if I do this, and dequeue an item, I get the error "AttributeError: Queue instance has no attribute 'front'." I guess my function doesn't properly assign the new front of the queue? I'm not sure how to fix it though. I don't really want to start from scratch, so if there's a tweak to my code that would work, I'd prefer that—I'm not trying to minimize runtime so much as just get a feel for classes and things of that nature. Thanks in advance for any help, you guys are the best.

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  • How to put large text data (~20mb) into sql cs 3.5 database?

    - by Anindya Chatterjee
    I am using following query to insert some large text data : internal static string InsertStorageItem = "insert into Storage(FolderName, MessageId, MessageDate, StorageData) values ('{0}', '{1}', '{2}', @StorageData)"; and the code I am using to execute this query is as follows : string content = "very very large data"; string query = string.Format(InsertStorageItem, "Inbox", "AXOGTRR1445/DSDS587444WEE", "4/19/2010 11:11:03 AM"); var command = new SqlCeCommand(query, _sqlConnection); var paramData = command.Parameters.Add("@StorageData", System.Data.SqlDbType.NText); paramData.Value = content; paramData.SourceColumn = "StorageData"; command.ExecuteNonQuery(); But at the last line I am getting this following error : System.Data.SqlServerCe.SqlCeException was unhandled by user code Message=The data was truncated while converting from one data type to another. [ Name of function(if known) = ] Source=SQL Server Compact ADO.NET Data Provider HResult=-2147467259 NativeError=25920 StackTrace: at System.Data.SqlServerCe.SqlCeCommand.ProcessResults(Int32 hr) at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommandText(IntPtr& pCursor, Boolean& isBaseTableCursor) at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommand(CommandBehavior behavior, String method, ResultSetOptions options) at System.Data.SqlServerCe.SqlCeCommand.ExecuteNonQuery() at Chithi.Client.Exchange.ExchangeClient.SaveItem(Item item, Folder parentFolder) at Chithi.Client.Exchange.ExchangeClient.DownloadNewMails(Folder folder) at Chithi.Client.Exchange.ExchangeClient.SynchronizeParentChildFolder(WellKnownFolder wellknownFolder, Folder parentFolder) at Chithi.Client.Exchange.ExchangeClient.SynchronizeFolders() at Chithi.Client.Exchange.ExchangeClient.WorkerThreadDoWork(Object sender, DoWorkEventArgs e) at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e) at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument) InnerException: Now my question is how am I supposed to insert such large data to sqlce db? Regards, Anindya Chatterjee http://abstractclass.org

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  • XML: what processing rules apply for values intertwined with tags?

    - by iCE-9
    I've started working on a simple XML pull-parser, and as I've just defuzzed my mind on what's correct syntax in XML with regards to certain characters/sequences, ignorable whitespace and such (thank you, http://www.w3schools.com/xml/xml_elements.asp), I realized that I still don't know squat about what can be sketched up as the following case (which Validome finds well-formed very much; note that I only want to use xml files for data storage, no entities, DTD or Schemas needed): <bookstore> <book id="1"> <author>Kurt Vonnegut Jr.</author> <title>Slapstick</title> </book> We drop a pie here. <book id="2">Who cares anyway? <author>Stephen King</author> <title>The Green Mile</title> </book> And another one here. <book id="3"> <author>Next one</author> <title>This time with its own title</title> </book> </bookstore> "We drop a pie here." and "And another one here." are values of the 'bookstore' element. "Who cares anyway?" is a value related to the second 'book' element. How are these processed, if at all? Will "We drop a pie here." and "Another one here." be concatenated to form one value for the 'bookstore' element, or are they treated separately, stored somewhere, affecting the outcome of the parsing of the element they belong to, or...?

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  • Drawing only part of a texture OpenGL ES iPhone

    - by Ben Reeves
    ..Continued on from my previous question I have a 320*480 RGB565 framebuffer which I wish to draw using OpenGL ES 1.0 on the iPhone. - (void)setupView { glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_CROP_RECT_OES, (int[4]){0, 0, 480, 320}); glEnable(GL_TEXTURE_2D); } // Updates the OpenGL view when the timer fires - (void)drawView { // Make sure that you are drawing to the current context [EAGLContext setCurrentContext:context]; //Get the 320*480 buffer const int8_t * frameBuf = [source getNextBuffer]; //Create enough storage for a 512x512 power of 2 texture int8_t lBuf[2*512*512]; memcpy (lBuf, frameBuf, 320*480*2); //Upload the texture glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 512, 512, 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, lBuf); //Draw it glDrawTexiOES(0, 0, 1, 480, 320); [context presentRenderbuffer:GL_RENDERBUFFER_OES]; } If I produce the original texture in 512*512 the output is cropped incorrectly but other than that looks fine. However using the require output size of 320*480 everything is distorted and messed up. I'm pretty sure it's the way I'm copying the framebuffer into the new 512*512 buffer. I have tried this routine int8_t lBuf[512][512][2]; const char * frameDataP = frameData; for (int ii = 0; ii < 480; ++ii) { memcpy(lBuf[ii], frameDataP, 320); frameDataP += 320; } Which is better, but the width appears to be stretched and the height is messed up. Any help appreciated.

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  • Hybrid EAV/CR model via WCF (and statically-typed language)?

    - by Pat
    Background I'm working on the architecture for a cloud-based LOB application, using Silverlight for the client, WCF, ASP.NET/C# for server and SQL Server for storage. The data model requires some flexibility per user (ability to add custom properties and define validation rules for them, for example), and a hybrid EAV/CR persistence model on the server side will suit nicely. Problem I need an efficient and maintainable technology and approach to handle the transformation from the persisted EAV model to/from WCF (and similarly allow the client to bind to the resulting data - DataGrid is a key UI element)? Admission: I don't yet know enough about WCF to understand if it supports ExpandoObject directly, but I suspect it will. Options I started off looking at WCF RIA services, but quickly discovered they're heavily dependent upon both static type data and compile-time code generation. Neither of these appeal. The options I'm considering include: Using WCF RIA services and pass the data over the network directly in EAV form (i.e. Dictionary), and handle the binding issue purely on the client side (like this) Using a dynamic language (probably IronPython) to handle both ends of the communication, with plumbing to generate the necessary CLR type data on the client to allow binding, and transform to/from EAV form on the server (spam preventer stopped me from posting a URL here, I'll try it in a comment). Dynamic LINQ (CreateClass() and friends), although I'm way out of my depth there and don't know what the limitations on that approach might be yet. I'm interested in comments on these approaches as well as alternative approaches that might solve the problem. Other Notes The Silverlight client will not be the only consumer of the service, making me slightly uncomfortable with option #1 above. While the data model is flexible, it's not expected to be modified heavily. For argument's sake, we could assume that we might have 25 distinct data models active at a given time, with something like 10-20 unique data fields/rules each. Modifications to the data model will happen infrequently (typically when a new user is initially configured).

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  • Would it be possible to have a UTF-8-like encoding limited to 3 bytes per character?

    - by dan04
    UTF-8 requires 4 bytes to represent characters outside the BMP. That's not bad; it's no worse than UTF-16 or UTF-32. But it's not optimal (in terms of storage space). There are 13 bytes (C0-C1 and F5-FF) that are never used. And multi-byte sequences that are not used such as the ones corresponding to "overlong" encodings. If these had been available to encode characters, then more of them could have been represented by 2-byte or 3-byte sequences (of course, at the expense of making the implementation more complex). Would it be possible to represent all 1,114,112 Unicode code points by a UTF-8-like encoding with at most 3 bytes per character? If not, what is the maximum number of characters such an encoding could represent? By "UTF-8-like", I mean, at minimum: The bytes 0x00-0x7F are reserved for ASCII characters. Byte-oriented find / index functions work correctly. You can't find a false positive by starting in the middle of a character like you can in Shift-JIS.

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  • Storing Arbitrary Contact Information in Ruby on Rails

    - by Anthony Chivetta
    Hi, I am currently working on a Ruby on Rails app which will function in some ways like a site-specific social networking site. As part of this, each user on the site will have a profile where they can fill in their contact information (phone numbers, addresses, email addresses, employer, etc.). A simple solution to modeling this would be to have a database column per piece of information I allow users to enter. However, this seems arbitrary and limited. Further, to support allowing users to enter as many phone numbers as they would like requires the addition of another database table and joins. It seems to me that a better solution would be to serialize all the contact information entered by a user into a single field in their row. Since I will never be conditioning a SQL query on this information, such a solution wouldn't be any less efficient. Ideally, I would like to use a vCard as my serialization format. vCards are the standard solution to storing contact information across the web, and reusing tested solutions is a Good Thing. Alternative serialization formats would include simply marshaling a ruby hash, or YAML. Regardless of serialization format, supporting the reading and updating of this information in a rails-like way seems to be a major implementation challenge. So, here's the question: Has anyone seen this approach used in a rails application? Are there any rails plugins or gems that make such a system easy to implement? Ideally what I would like is an acts_as_vcard to add to my model object that would handle editing the vcard for me and saving it back to the database.

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  • error C3662: override specifier 'new' only allowed on member functions of managed classes

    - by William
    Okay, so I'm trying to override a function in a parent class, and getting some errors. here's a test case #include <iostream> using namespace std; class A{ public: int aba; void printAba(); }; class B: public A{ public: void printAba() new; }; void A::printAba(){ cout << "aba1" << endl; } void B::printAba() new{ cout << "aba2" << endl; } int main(){ A a = B(); a.printAba(); return 0; } And here's the errors I'm getting: Error 1 error C3662: 'B::printAba' : override specifier 'new' only allowed on member functions of managed classes c:\users\test\test\test.cpp 12 test Error 2 error C2723: 'B::printAba' : 'new' storage-class specifier illegal on function definition c:\users\test\test\test.cpp 19 test How the heck do I do this?

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  • question about MySQL database migration

    - by WilliamLou
    Hi there: If I have a MySQL database with several tables on a live server, now I would like to migrate this database to another server. Of course, the migration I mean here involves some database tables, for example: add some new columns to several tables, add some new tables etc.. Now, the only method I can think of is to use some php/python(two scripts I know) script, connect two databases, dump the data from the old database, and then write into the new database. However, this method is not efficient at all. For example: in old database, table A has 28 columns; in new database, table A has 29 columns, but the extra column will have default value 0 for all the old rows. My script still needs to dump the data row by row and insert each row into the new database. Is there any tools or a better method than writing a script yourself? Here, I dont need to worry about multithread writing problems etc.., I mean the old database will be down (not open to public usage etc.., only for upgrade ) for a while. Thanks!!

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  • Database design and foreign keys: Where should they be added in related tables?

    - by Carvell Fenton
    I have a relatively simple subset of tables in my database for tracking something called sessions. These are academic sessions (think offerings of a particular program). The tables to represent a sessions information are: sessions session_terms session_subjects session_mark_item_info session_marks All of these tables have their own primary keys, and are like a tree, in that sessions have terms, terms have subjects, subjects have mark items, etc. So each on would have at least its "parent's" foreign key. My question is, design wise is it a good idea to include the sessions primary key in the other tables as a foreign key to easily select related session items, or is that too much redundency? If I include the session foreign key (or all parent foreign keys from tables up the heirarchy) in all the tables, I can easily select all the marks for a session. As an example, something like SELECT mark FROM session_marks WHERE sessionID=... If I don't, then I would have to combine selects with something like WHERE something IN (SELECT... Which approach is "more correct" or efficient? Thanks in advance!

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