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• DataType for storing a long serial number (10 bytes)

  - by CrimsonX

  We have a device which has a 10 byte serial number which must be read into our application and stored into a .net datatype. In the device it is stored as an unsigned 10-byte (80-bit) number. I don't expect we will be performing any mathematical operations on this number, but only displaying it to the user. The .NET framework doesn't have a built in UNIT128 to store this datatype. My suggestion for storing this datatype is to create a 10 element byte array and read in the data into this array. Are there any better solutions to this problem? Note: I have seen in this question that a GUID is a 128 byte signed integer, but it seems like a bad idea to use a GUID in this fashion. Any other suggestions?

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• Writing my own iostream utility class: Is this a good idea?

  - by Alex

  I have an application that wants to read word by word, delimited by whitespace, from a file. I am using code along these lines: std::istream in; string word; while (in.good()) { in>>word; // Processing, etc. ... } My issue is that the processing on the words themselves is actually rather light. The major time consumer is a set of mySQL queries I run. What I was thinking is writing a buffered class that reads something like a kilobyte from the file, initializes a stringstream as a buffer, and performs extraction from that transparently to avoid a great many IO operations. Thoughts and advice?

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• Tweak Data in Doctrine Migration (say, by running some arbitrary queries)

  - by timdev

  I've got a migration that creates a couple of columns that act as foreign keys. In particular, I'm adding a creator_id and owner_id column to a model. These foreign keys indicate who created, and who currently owns, a particular kind of domain object. Users are managed by sfDoctrineGuardPlugin. What I'd like to do, for the purpose of the migration, is look up the (active) user with the lowest id, and default creator_id/owner_id to that. I don't see any particularly obvious/proper way to run arbitrary operations on the database during a migration. Does anyone know how?

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• Why might different computers calculate different arithmetic results in VB.NET?

  - by Eyal

  I have some software written in VB.NET that performs a lot of calculations, mostly extracting jpegs to bitmaps and computing calculations on the pixels like convolutions and matrix multiplication. Different computers are giving me different results despite having identical inputs. What might be the reason? Edit: I can't provide the algorithm because it's proprietary but I can provide all the relevant operations: ULong \ ULong (Turuncating division) Bitmap.Load("filename.bmp') (Load a bitmap into memory) Bitmap.GetPixel(Integer, Integer) (Get a pixel's brightness) Double + Double Double * Double Math.Sqrt(Double) Math.PI Math.Cos(Double) ULong - ULong ULong * ULong ULong << ULong List.OrderBy(Of Double)(Func) Hmm... Is it possible that OrderBy is using a non-stable QuickSort and that QuickSort is using a random pivot? Edit: Just tested, nope. The sort is stable.

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• Typecasting a floating value or using the math.h floor* functions?

  - by nobody

  Hi, I am coding up an implementation of Interpolation Search in C. The question is actually rather simple, I need to use the floating operations to do linear interpolation to find the correct index which will eventually be an integer result. In particular my probe index is: t = i + floor((((k-low)/(high-low)) * (j-i))); where, i,j,k,t are unsigned ints, and high,low are doubles. Would this be equivalent to: t = i + (unsigned int)(((k-low)/(high-low)) * (j-i)); Is there any reason I would actually want to use math.h floor* functions over just a simple (int) typecast?

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• How atomic *should* I make an Ajax form?

  - by b. e. hollenbeck

  I have some web forms that I'm bringing over with AJAX, and as I was dealing with the database on the back end, I thought that it might be easier to just handle each input on the form atomically with AJAX, saving the form in 'real time' as the user edits it. The forms are ~20 fields of administrative settings. Would this create massive overhead with the app, cause it to be error-prone, or is this a feasible idea? Of course, contingent operations (like a checkbox that then requires a text entry) would be held until the textbox gained and lost focus. Comments?

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• Upsert - Efficient Update or Insert in VB.Net, SQL Server

  - by HK1

  I'm trying to understand how to streamline the process of inserting a record if none exists or updating a record if it already exists. I'm not using stored procedures, although maybe that would be the most efficient way of doing this. The actual scenario in which this is necessary is saving a user preference/setting to my SettingsUser table. In MS Access I would typically pull a DAO recordset looking for the specified setting. If the recordset comes back empty then I know I need to add a new record which I can do with the same recordset object. On the other hand, if it isn't empty, I can just update the setting's value right away. In theory, this is only two database operations. What is the recommended way of doing this in .NET?

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• How many instructions to access pointer in C?

  - by Derek

  Hi All, I am trying to figure out how many clock cycles or total instructions it takes to access a pointer in C. I dont think I know how to figure out for example, p-x = d-a + f-b i would assume two loads per pointer, just guessing that there would be a load for the pointer, and a load for the value. So in this operations, the pointer resolution would be a much larger factor than the actual addition, as far as trying to speed this code up, right? This may depend on the compiler and architecture implemented, but am I on the right track? I have seen some code where each value used in say, 3 additions, came from a f2->sum = p1->p2->p3->x + p1->p2->p3->a + p1->p2->p3->m type of structure, and I am trying to define how bad this is

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• Implement a simple class in your favorite language.

  - by Oscar Reyes

  I'm doing this to learn syntax of different programming languages. So, how would you defined the following class along with with it's operations in your favorite programming language? Image generated by http://yuml.me/ And a main method or equivalent to invoke it: For instance, for Java it would be: ... public static void main( String [] args ) { Fraction f = new Fraction(); f.numerator( 2 ); f.denominator( 5 ); f.print(); } ....

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• Are there ways to improve NHibernate's performance regarding entity instantiation?

  - by denny_ch

  Hi folks, while profiling NHibernate with NHProf I noticed that a lot of time is spend for entity building or at least spend outside the query duration (database roundtrip). The project I'm currently working on prefetches some static data (which goes into the 2nd level cache) at application start. There are about 3000 rows in the result set (and maybe 30 columns) that is queried in 75 ms. The overall duration observed by NHProf is about 13 SECONDS! Is this typical beheviour? I know that NHibernate shouldn't be used for bulk operations, but I didn't thought that entity instantiation would be so expensive. Are there ways to improve performance in such situations or do I have to live with it? Thx, denny_ch

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• Interpreters: How much simplification?

  - by Ray

  In my interpreter, code like the following x=(y+4)*z echo x parses and "optimizes" down to four single operations performed by the interpreter, pretty much assembly-like: add 4 to y multiply <last operation result> with z set x to <last operation result> echo x In modern interpreters (for example: CPython, Ruby, PHP), how simplified are the "opcodes" for which are in end-effect run by the interpreter? Could I achieve better performance when trying to keep the structures and commands for the interpreter more complex and high-level? That would be surely a lot harder, or?

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• Custom User Management for Google App Engine Java

  - by Gopi

  I am using GAE Java for a multi-user application. There are multiple users with different roles. Each user can login, do some operations and logout. The business restricts me from using Google User Service and I need to implement my own for authentication and session management. Can anyone please share with me how should I go about implementing my own user management? I have read its very tricky to implement own user management. Any pointers in terms of best approaches/ design / existing frameworks if any ? I could see some similar posts but they are for python.

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• PHP: OOP and methods

  - by Pirkka

  Hello I`ve been wondering how to implement methods in a class. Could someone explain me what means if one does OOP in procedural style? Here is an example: class Fld extends Model { private $file; private $properties = array(); public function init($file) { $this->file = $file; $this->parseFile(); } private function parseFile() { // parses the file foreach($this->file as $line)...... .................. $this->properties = $result; } } I mean is it a good thing to have methods like these that do operations for the class properties like that. Or should I pass the class property as method parameter... I mean this would cause error if the file property wouldnt be declared.

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• Looking for solution to persist rows sequence in a database table that allow efficient reordering at

  - by Chau Chee Yang

  I have a database table. There is a field name "Sequence" that indicate sequence when user presents the rows in report or grid visually. When the rows are retrieved and presented in a grid, there are few UI gadget that allow user to reorder the rows arbitrary. The new sequence will be persist in database table when user commit the changes. Here are some UI operations: Move to first Move to last Move up 1 row Move down 1 row multi-select rows and move up or down multi-select rows and drag to new position For operation like "Move to first" or "Move to Last", it usually involve many rows and the sequence those rows would need to be updated accordingly. This may not be efficient enough at runtime. It is a common practice to use INTEGER as sequence's data type. Other solution is using "DOUBLE" or "FLOAT" that could overcome the mass update of row sequence but we will face problem if we reach the limit of precision.

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• Want procmail to run a custom python script, everytime a new mail shows up

  - by Maddy

  I have a pretty usual requirement with procmail but I am unable to get the results somehow. I have procmailrc file with this content: :0 * ^To.*@myhost | /usr/bin/python /work/scripts/privilege_emails_forward.py Wherein my custom python script(privilege_emails_forward.py) will be scanning through the email currently received and do some operations on the mail content. But I am unable to get the script getting executed at the first shot(let alone scanning through the mail content). Is this a correct way of invoking an external program(python) as soon as new mail arrives? And how does my python program(privilege_emails_forward.py) will receive the mail as input? I mean as sys.argv or stdin????

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• Prolog - Finding the current directory, relative directory for 'tell' predicate

  - by Bharat

  I'm having trouble trying to figure out how to get prolog to spit out a text file where I want it to. I'm currently doing a bunch of operations and then using tell('output.txt') to record the output. Now the problem is that when I do this, it creates this file in the SWI \bin\ folder. I was wondering if there's a way to make it create this file in the directory containing the actual .pl file. So even if the file was moved (and it will be), the text file gets created right where the source file is. Long story short, is there a way to get the location of the source file once the source file has been consulted? Many Thanks!

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• How should I port this Prototype to JQuery?

  - by blu

  There is currently this Prototype code that does a PUT: new Ajax.Request(someUrl, { method: 'put', parameters: { 'foo': bar }, onSuccess: function(response) { } .bind(this) }); I found this post but the solution uses an extra parameter supported by RoR, however I am targeting an ASP.NET backend. I searched a bit and found that not all browsers support PUT operations so apparently this could fail in certain browsers? This is already in prod, so a direct port would be fine for now I suppose. As an aside, what is the deal with the bind(this) in the onSuccess function?

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• C++ threaded class design from non-threaded class

  - by macs

  I'm working on a library doing audio encoding/decoding. The encoder shall be able to use multiple cores (i.e. multiple threads, using boost library), if available. What i have right now is a class that performs all encoding-relevant operations. The next step i want to take is to make that class threaded. So i'm wondering how to do this. I thought about writing a thread-class, creating n threads for n cores and then calling the encoder with the appropriate arguments. But maybe this is an overkill and there is no need for another class, so i'm going to make use of the "user interface" for thread-creation. I hope there are any suggestions.

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• Genetic programming in c++, library suggestions?

  - by shuttle87

  I'm looking to add some genetic algorithms to an Operations research project I have been involved in. Currently we have a program that aids in optimizing some scheduling and we want to add in some heuristics in the form of genetic algorithms. Are there any good libraries for generic genetic programming/algorithms in c++? Or would you recommend I just code my own? I should add that while I am not new to c++ I am fairly new to doing this sort of mathematical optimization work in c++ as the group I worked with previously had tended to use a proprietary optimization package. We have a fitness function that is fairly computationally intensive to evaluate and we have a cluster to run this on so parallelized code is highly desirable. So is c++ a good language for this? If not please recommend some other ones as I am willing to learn another language if it makes life easier. thanks!

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• SmartGWT Server File Browser

  - by jluzwick

  Hi All: I have been looking for a SmartGWT example that would show me how to build a File Browser widget that takes the files from the local server's root directory. The user would be shown the files through the browser which they could then select to perform some processing operations. So far I have thought of using SmartGWT's Tree-Data Binding-Load from Local Data Widget and then grabbing a list of the directories using: new File("\").listFiles(); My Question is: Is there a better way to do this? Has someone already thought of this and has an example of their code that I can see? PS: I'm fairly new to GWT and Web Services but fairly competent with Java. If you believe there is a better way to do this (while still doing this through the web and not using Applets, please tell me). Thanks

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• How can i add an image in html email from lotus domino agent?

  - by mike_x_

  i want to add a simple image into an email which i want to send from a lotus agent. I paste below a part of the code: StringBuilder sb = new StringBuilder(); sb.append("<div><img src=\"http://goo.gl/lziMZN\"></div>"); email.setHTMLPart(sb.toString()); email.send("[email protected]"); I also tried to use an image from my image resources in the nsf. Whatever i tried i get an empty image area (browser-no-image icon) in the email i receive. I also have checked "Allow restricted operations" in my agent. I would prefer it if there is a solution to use an image from my resources and not an external link. Any solutions?

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• Domain Model and Contracts

  - by devoured elysium

  I am modelling a DVD Rental Store: A Client gives its clientNumber to the System. The System checks whenever the given clientNumber is valid. The Client gives the name of the DVD he wants to rent. ... n. ...I will later have to form an association between a new instance of "RentDVD" class concept to the current Client c. My Domain Model is something like: I've made the Contract for the first and second operations as: Preconditions: none Postconditions: there exists a Client c such that c.clientNumber = clientNumber. Now, I don't know if I should form an association between this Client c and the DVDStore(that I intend to use as front-end). If I don't make the association, how will I later be able to "reference" this same Client? Should I be making an association between Client and a different concept? Thanks

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• App engine downtime

  - by DutrowLLC

  I've noticed that google app engine seems to have a fair amount of downtime where they place the datastore into read-only mode. Frequently this downtime is in the middle of the day. Is this something that is happening only during early development, or is this something that I can expect to be always be occurring? I've developing an application that helps small businesses handle their operations. One thing that it does is take appointments, another is route phone calls. I'd like some suggestions on how to handle times when the datastore is in read-only such as: What if our client is on the phone with the customer and is taking down an appointment and the datastore is in read-only? It would not be acceptable to ask the client to come back later to save, especially if its in the middle of the day. What if there is an incoming call and the application can not store the record or properly route the call due to database writes being unavailable? How are these types of issues normally handled?

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• How to replace values in multi-valued ESE column?

  - by Soonts

  I have a multi-valued short ASCII text column in one of the tables in my ESE database, that holds the person's phone numbers. I have the new set of values, and I'd like to wipe the old values completely, and only use the new values. The JET_bitSetRevertToDefaultValue bit doesn't seem to work. While the MSDN documentation says "It causes the column to return the default column value on subsequent retrieve column operations. All existing column values are removed.", I found that it does nothing (no return value is returned). Or, is there an easy way to find out how many values does the column contain (this could be zero, e.g. when I'm doing an insertion, not update)? If it was, I could just run a loop from 'nValues' to 1, erasing the value by setting it to the null while providing the itagSequence value, to achieve what I want. I'm programming C#, and using the latest version of ManagedEsent library. Thanks in advance!

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• Strategies for generating Zend Cache Keys

  - by emeraldjava

  ATM i'm manually generating a cache key based on the method name and parameters, then follow to the normal cache pattern. This is all done in the Controller and i'm calling a model class that 'extends Zend_Db_Table_Abstract'. public function indexAction() { $cache = Zend_Registry::get('cache'); $individualleaguekey = sprintf("getIndividualLeague_%d_%s",$leagueid,$division->code); if(!$leaguetable = $cache->load($individualleaguekey)) { $table = new Model_DbTable_Raceresult(); $leaguetable = $table->getIndividualLeague($leagueid,$division,$races); $cache->save($leaguetable, $individualleaguekey); } $this->view->leaguetable = $leaguetable; .... I want to avoid the duplication of parameters to the cache creation method and also to the model method, so i'm thinking of moving the caching logic away from my controller class and into model class packaged in './model/DbTable', but this seems incorrect since the DB model should only handle SQL operations. Any suggestions on how i can implement a clean patterned solution?

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