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• What's are the best readings to start using WPF instead of WinForms?

  - by Ivan

  Keeping in mind what CannibalSmith once said - "All the answers are saying "WPF is different". That's a huge understatement. You not only have to learn lots of new stuff - you must forget everything you've learned from Forms. It's a completely new way of doing UI." .. and having many years of experience with visual Windows desktop applications development (VB6, Borland C++ Builder VCL, WinForms) (which is hard to forget), how do I quickly move to developing to say well-formed WPF applications with Visual Studio? I don't need boozy-woozy graphics to give my app look and feel of a Hollywood blockbuster or a million dollar pyjamas. I always loved tidiness of standard Windows common controls and UI design guidelines, end even more I enjoyed them under Vista Glass Aero Graphite sauce. I am perfectly satisfied with WinForms but I want to my applications to be built of the most efficient and up-to-date standard technologies and architectured according to the most efficient and flexible patterns of today and tomorrow, leveraging interface-based integration and functionality reuse and to take all advantages of modern hardware and APIs to maximize performance, usability, reliability, maintainability, extensibility, etc. I very much like the idea of separating view, logic and data, letting a view to take all advantages of the platform (may it run as a web browser applet on a thin client or as a desktop application on a PC with a latest GPU), letting logic be reused, parallelized and seamlessly evolve, storing data in a well structured format in a right place. But... while moving from VB6 to Borland C++ Builder was very easy (no books/tutorials needed to turn it on and start working) (assuming I already knew C++), moving from BCB to WinForms was the same seamless, it does not seem any obvious to me how to do with WPF. So how do I best convert myself from a WinForms developer into a right-way thinking and doing WPF developer?

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• 48-bit bitwise operations in Javascript?

  - by randomhelp

  I've been given the task of porting Java's Java.util.Random() to JavaScript, and I've run across a huge performance hit/inaccuracy using bitwise operators in Javascript on sufficiently large numbers. Some cursory research states that "bitwise operators in JavaScript are inherently slow," because internally it appears that JavaScript will cast all of its double values into signed 32-bit integers to do the bitwise operations (see https://developer.mozilla.org/En/Core_JavaScript_1.5_Reference/Operators/Bitwise_Operators for more on this.) Because of this, I can't do a direct port of the Java random number generator, and I need to get the same numeric results as Java.util.Random(). Writing something like this.next = function(bits) { if (!bits) { bits = 48; } this.seed = (this.seed * 25214903917 + 11) & ((1 << 48) - 1); return this.seed >>> (48 - bits); }; (which is an almost-direct port of the Java.util.Random()) code won't work properly, since Javascript can't do bitwise operations on an integer that size.) I've figured out that I can just make a seedable random number generator in 32-bit space using the Lehmer algorithm, but the trick is that I need to get the same values as I would with Java.util.Random(). What should I do to make a faster, functional port?

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• Best way to manipulate and compare strings

  - by vtortola

  I'm developing a REST service, so a request could be something like this: /Data/Main/Table=Customers/ I need to get the segments one by one, and for each segment I will decide wich object I'm going to use, after I'll pass to that object the rest of the query so it can decide what to do next. Basically, the REST query is a path on a tree :P This imply lots String operations (depending on the query complexity), but StringBuilder is useful just for concatenations and remove, you cannot perform a search with IndexOf or similar. I've developed this class that fulfill my requirement, but the problem is that is manipulating Strings, so every time I get one segment ... I'll create extra Strings because String is an inmutable data type: public class RESTQueryParser { String _query; public RESTQueryParser(String query) { _query = query; } public String GetNext() { String result = String.Empty; Int32 startPosition = _query.StartsWith("/", StringComparison.InvariantCultureIgnoreCase) ? 1 : 0; Int32 i = _query.IndexOf("/", startPosition, StringComparison.InvariantCultureIgnoreCase) - 1; if (!String.IsNullOrEmpty(_query)) { if (i < 0) { result = _query.Substring(startPosition, _query.Length - 1); _query = String.Empty; } else { result = _query.Substring(startPosition, i); _query = _query.Remove(0, i + 1); } } return result; } } The server should support a lot of calls, and the queries could be huge, so this is gonna be a very repetitive task. I don't really know how big is the impact on the memory and the performance, I've just readed about it in some books. Should I implement a class that manage a Char[] instead Strings and implement the methods that I want? Or should be ok with this one? Regular expressions maybe?

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• Linq Query to Update Nested Array Items?

  - by Brett

  I have an object structure generated from xsd.exe. Roughly, it consists of 3 nested arrays: protocols, sources and reports. The xml looks like this: <protocols> <protocol> <source> <report /> <report /> </source> <source> <report /> <report /> </source> </protocol> <!-- more protocols --> </protocols> I need to update a single "Report" within the data structure. A brute force algorithm is shown below. I know that this could be done using XDocument and Linq, but I'd prefer to update the data structure and then serialize the structure back to disk. Thoughts? Brett bool updated = false; foreach (ProtocolsProtocol protocol in protocols.Protocol) { if (updated) break; foreach (ProtocolsProtocolSource source in protocol.Source) { if (updated) break; for (int i = 0; i < source.Report.Length; i++) { ProtocolsProtocolSourceReport currentReport = source.Report[i]; if (currentReport.Id == report.Id) { currentReport.Attribute1 = report.Attribute1; currentReport.Attribute2 = report.Attribute2; updated = true; break; } } } }

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• How do I cast <T> to varbinary and be still be able to perform a CONVERT on the sql side? Implicatio

  - by Biff MaGriff

  Hello, I'm writing this application that will allow a user to define custom quizzes and then allow another user to respond to the questions. Each question of the quiz has a corresponding datatype. All the responses to all the questions are stored vertically in my [Response] table. I currently use 2 fields to store the response. //Response schema ResponseID int QuizPersonID int QuestionID int ChoiceID int //maps to Choice table, used for drop down lists ChoiceValue varbinary(MAX) //used to store a user entered value I'm using .net 3.5 C# SQL Server 2008. I'm thinking that I would want to store different datatypes in the same field and then in my SQL report proc I would CONVERT to the proper datatype. I'm thinking this is ideal because I only have to check one field. I'm also thinking it might be more trouble than it is worth. I think my other options are to; store the data as strings in the db (yuck), or to have a column for each datatype I might use. So what I would like to know is, how would I format my datatypes in C# so that they can be converted properly in SQL? What is the performance hit for converting in SQL? Should I just make a whole wack of columns for each datatype?

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• Versioning friendly, extendible binary file format

  - by Bas Bossink

  In the project I'm currently working on there is a need to save a sizable data structure to disk (edit: think dozens of MB's). Being an optimist, I thought that there must be a standard solution for such a problem; however, up to now I haven't found a solution that satisfies the following requirements: .NET 2.0 support, preferably with a FOSS implementation Version friendly (this should be interpreted as: reading an old version of the format should be relatively simple if the changes in the underlying data structure are simple, say adding/dropping fields) Ability to do some form of random access where part of the data can be extended after initial creation (think of this as extending intermediate results) Space and time efficient (XML has been excluded as option given this requirement) Options considered so far: Protocol Buffers: was turned down by verdict of the documentation about Large Data Sets - since this comment suggested adding another layer on top, this would call for additional complexity which I wish to have handled by the file format itself. HDF5,EXI: do not seem to have .net implementations SQLite/SQL Server Compact edition: the data structure at hand would result in a pretty complex table structure that seems too heavyweight for the intended use BSON: does not appear to support requirement 3. Fast Infoset: only seems to have paid .NET implementations. Any recommendations or pointers are greatly appreciated. Furthermore if you believe any of the information above is not true, please provide pointers/examples to prove me wrong.

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• Detecting duplicate values in a column of a Datatable while traversing through It

  - by Ashish Gupta

  I have a Datatable with Id(guid) and Name(string) columns. I traverse through the data table and run a validation criteria on the Name (say, It should contain only letters and numbers) and then adding the corresponding Id to a List If name passes the validation. Something like below:- List<Guid> validIds=new List<Guid>(); foreach(DataRow row in DataTable1.Rows) { if(IsValid(row["Name"]) { validIds.Add((Guid)row["Id"]); } } In addition to this validation I should also check If the name is not repeating in the whole datatable (even for the case-sensitiveness), If It is repeating, I should not add the corresponding Id in the List. Things I am thinking/have thought about:- 1) I can have another List, check for the "Name" in the same, If It exists, will add the corresponding Guild 2) I cannot use HashSet as that would treat "Test" and "test" as different strings and not duplicates. 3) Take the DataTable to another one where I have the disctict names (this I havent tried and the code might be incorrect, please correct me whereever possible) DataTable dataTableWithDistinctName = new DataTable(); dataTableWithDistinctName.CaseSensitive=true CopiedDataTable=DataTable1.DefaultView.ToTable(true,"Name"); I would loop through the original datatable and check the existence of the "Name" in the CopiedDataTable, If It exists, I wont add the Id to the List. Are there any better and optimum way to achieve the same? I need to always think of performance. Although there are many related questions in SO, I didnt find a problem similar to this. If you could point me to a question similar to this, It would be helpful. Thanks

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• Contributing to a Linux distribution

  - by Big Al

  I'm interested in contributing to a Linux distro, but regarding the various distro's developer communities, I'm having a bit of trouble figuring out which one I'd most like to join. What languages I know: C, C++, Lua, Python, and fairly familiar with Perl (though I wouldn't say I "know" it). In particular, I have very little experience with x86 assembly besides hacking stuff together for performance tweaks, though that will be partially rectified soon. What I'm looking for: A community that provides plenty of opportunities for developers to work on various aspects of the distribution. To be honest I'm most interested in reading and working on the kernel source (in which case the distro doesn't matter), but it's pretty daunting and I figure getting into the Linux community and working with experienced Linux developers might give me a better idea of how to jump into the guts(let me know if this is bogus, or if you have any advice regarding that). So... Which distro has the "best" developer community in terms of organization, people who are fun to work with, and opportunities to contribute? I've read various "Contributing to XXX" pages and mailing lists for distros like Ubuntu, OpenSuse, Fedora, etc. but I'd rather get a more personal testament from an actual developer.

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• Recursively adding threads to a Java thread pool

  - by Leith

  I am working on a tutorial for my Java concurrency course. The objective is to use thread pools to compute prime numbers in parallel. The design is based on the Sieve of Eratosthenes. It has an array of n bools, where n is the largest integer you are checking, and each element in the array represents one integer. True is prime, false is non prime, and the array is initially all true. A thread pool is used with a fixed number of threads (we are supposed to experiment with the number of threads in the pool and observe the performance). A thread is given a integer multiple to process. The thread then finds the first true element in the array that is not a multiple of thread's integer. The thread then creates a new thread on the thread pool which is given the found number. After a new thread is formed, the existing thread then continues to set all multiples of it's integer in the array to false. The main program thread starts the first thread with the integer '2', and then waits for all spawned threads to finish. It then spits out the prime numbers and the time taken to compute. The issue I have is that the more threads there are in the thread pool, the slower it takes with 1 thread being the fastest. It should be getting faster not slower! All the stuff on the internet about Java thread pools create n worker threads the main thread then wait for all threads to finish. The method I use is recursive as a worker can spawn more worker threads. I would like to know what is going wrong, and if Java thread pools can be used recursively.

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• "Cannot open user default database" error with "User Instance=True"

  - by Keith

  I have a desktop application that uses Sql user instancing. This is my connection string: "Data Source=.\SqlExpress; AttachDbFilename=C:\path\file.mdf; Integrated Security=True; User Instance=True; Connect Timeout=100;" My application creates this DB, downloads a load of data into it from a web service and then does a lot of actions with it. The problem comes when I attempt to re-open the connection. I get a SqlException: "Cannot open user default database. Login failed. Login failed for user 'myDomain\myusername'." This error makes no sense in this context - I have no default database. I'm logging in to an instance created just for the current application, running separately from SqlExpress. There's no other way to connect to this DB. If I start the SqlExpress service and connect to the default instance it won't be visible. It only exists for this application. The file on disk is locked by the SqlExpress instance service running under the application. if I stop the app and restart it the connection works first time, but fails on re-opening. If I just stop the app I can delete the .mdf files and begin again, but it still crashes when I re-open the connection. As my app started the instance running as me my current user should have access to every DB in the instance. This doesn't happen for other users of the same code, which suggests that it's a SQL config issue. Does anyone have any idea what causes this and how to work around it?

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• How can I get PowerShell Added-Types to use Added References

  - by Scott Weinstein

  I'm working on a PoSh project that generates CSharp code, and then Add-Types it into memory. The new types use existing types in an on disk DLL, which is loaded via Add-Type. All is well and good untill I actualy try to invoke methods on the new types. Here's an example of what I'm doing: $PWD = "." rm -Force $PWD\TestClassOne* $code = " namespace TEST{ public class TestClassOne { public int DoNothing() { return 1; } } }" $code | Out-File tcone.cs Add-Type -OutputAssembly $PWD\TestClassOne.dll -OutputType Library -Path $PWD\tcone.cs Add-Type -Path $PWD\TestClassOne.dll $a = New-Object TEST.TestClassOne "Using TestClassOne" $a.DoNothing() "Compiling TestClassTwo" Add-Type -Language CSharpVersion3 -TypeDefinition " namespace TEST{ public class TestClassTwo { public int CallTestClassOne() { var a = new TEST.TestClassOne(); return a.DoNothing(); } } }" -ReferencedAssemblies $PWD\TestClassOne.dll "OK" $b = New-Object TEST.TestClassTwo "Using TestClassTwo" $b.CallTestClassOne() Running the above script gives the following error on the last line: Exception calling "CallTestClassOne" with "0" argument(s): "Could not load file or assembly 'TestClassOne,...' or one of its dependencies. The system cannot find the file specified." At AddTypeTest.ps1:39 char:20 + $b.CallTestClassOne <<<< () + CategoryInfo : NotSpecified: (:) [], MethodInvocationException + FullyQualifiedErrorId : DotNetMethodException What am I doing wrong?

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• Coherent access to mainframe files from Win32 application and IBM RDZ/Eclipse?

  - by Ira Baxter

  I have a suite of tools for processing IBM COBOL source code; these tools are built as Win32 applications and talk to Windows (including network) files using traditional Windows file system calls (open, close, read, write) and work just fine, thank you. I'd like to integrate these with Eclipse; we understand how to get Eclipse to do UI for us we think. The problem is that Eclipse/RDZ users access mainframe files through some IBM magic. In How does RDZ access mainframe files I tried to understand how Eclipse accessed files on a mainframe. Apparantly Eclipse/RDZ has a secret filesystem access backdoor not available to normal mortals. At issue is how our tools, reading some Windows-accessible file (local disk file, NFS to mainframe, ...) can associate such files with the files that Eclipse can access or is using? Ideally we'd like UI-integrated versions of our tools take an Eclipse file-name string for a mainframe file, pass it to our Windows application to process, have the Windows application open/read/process the file, and return results associated with that file to the Eclipse UI. Is there a canonical file name path that would be used with mainframe NFS that would be equivalent to the name or access object the Eclipse RDZ used to access the same file? Are all operations doable internally by Eclipse, doable by the mainframe NFS [for instance, can NFS read/update an element in a partitioned data set? Can Eclipse RDZ? Does it matter?] Is the mainframe file access available to custom Java code running under Eclipse RDZ (e.g., equivalents of open/close/read/write based on filename/path/something?) If so, can somebody steer me towards documentation describing the access methods? Anybody else already solve this problem or have a good suggestion?

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• Flash movies in inactive browser tabs pause or don't execute in real time

  - by ZenBlender

  I'm noticing some unexpected behavior. Some time in the last few months, a change in either Firefox, the Flash player, or both, has made it so that Flash movies that are in inactive browser tabs no longer execute in real time. They appear to still execute, but only in bursts, and not in a predictable way. This is a problem because I develop a Flash-based (Actionscript 2.0, Flash CS3) multiplayer game that maintains a network connection and allows players to chat, etc. Many of our players complain about Firefox crashing while playing the game. I have noticed it too, not too frequently, but it crashes several times a week. (Firefox crashes, I do not get a message from Flash player that indicates an infinite loop or problem in my code) My theory is that this new behavior is causing crashes when there is a lot of activity in my game, leading to lots of unhandled network traffic for my game getting buffered before Firefox/Flash will give it a chance to execute. Maybe this leads to a buffer overflow or missing packets, and as a result, something crashes. At times I will switch back to the tab that is running my game and discover a display bug, which looks as though Flash has simply failed to execute something that it was supposed to. I would assume this new behavior is on purpose, for example to prevent all the Flash-based advertisements in inactive tabs from executing and therefore killing performance. In a quick test on Chrome (5.0.342.9 beta), this "pausing" of Flash seems to be there as well, but somehow it seems much less of a problem. My users have only complained about Firefox crashing, not other browsers. My machine: Windows 7 x64 Firefox 3.6.3 Flash Player 10.1.50.426 My game: triplejack.com Any ideas? Ideally I'd like to disable this behavior for my Flash game so it can execute in real time even when in an inactive tab. Thanks for any help!

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• Using datetime float representation as primary key

  - by devanalyst

  From my experience I have learn that using an surrogate INT data type column as primary key esp. an IDENTITY key column offers better performance than using GUID or char/varchar data type column as primary key. I try to use IDENTITY key as primary key wherever possible. But recently I came across a schema where the tables were horizontally partitioned and were managed via a Partitioned view. So the tables could not have an IDENTITY column since that would make the Partitioned View non updatable. One work around for this was to create a dummy 'keygenerator' table with an identity column to generate IDs for primary key. But this would mean having a 'keygenerator' table for each of the Partitioned View. My next thought was to use float as a primary key. The reason is the following key algorithm that I devised DECLARE @KEY FLOAT SET @KEY = CONVERT(FLOAT,GETDATE())/100000.0 SET @KEY = @EMP_ID + @KEY Heres how it works. CONVERT(FLOAT,GETDATE()) gives float representation of current datetime since internally all datetime are represented by SQL as a float value. CONVERT(FLOAT,GETDATE())/100000.0 converts the float representation into complete decimal value i.e. all digits are pushed to right side of ".". @KEY = @EMP_ID + @KEY adds the Employee ID which is an integer to this decimal value. The logic is that the Employee ID is guaranteed to be unique across sessions since an employee cannot connect to an application more than once at the same time. And for the same employee each time a key will be generated the current datetime will be unique. In all an unique key across all employee sessions and across time. So for Emp Ids 11 and 12, I have key values like 12.40046693321566357, 11.40046693542361111 But my concern whether float data type as primary key offer benefits compared to choosing GUID or char/varchar as primary keys. Also important thing is because of partitioning the float column is going to be part of a composite key.

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• Improve speed of own debug visualizer for Delphi 2010

  - by netcodecz

  I wrote Delphi debug visualizer for TDataSet to display values of current row, source + screenshot: http://delphi.netcode.cz/text/tdataset-debug-visualizer.aspx . Working good, but very slow. I did some optimalization (how to get fieldnames) but still for only 20 fields takes 10 seconds to show - very bad. Main problem seems to be slow IOTAThread90.Evaluate used by main code shown below, this procedure cost most of time, line with ** about 80% time. FExpression is name of TDataset in code. procedure TDataSetViewerFrame.mFillData; var iCount: Integer; I: Integer; // sw: TStopwatch; s: string; begin // sw := TStopwatch.StartNew; iCount := StrToIntDef(Evaluate(FExpression+'.Fields.Count'), 0); for I := 0 to iCount - 1 do begin s:= s + Format('%s.Fields[%d].FieldName+'',''+', [FExpression, I]); // FFields.Add(Evaluate(Format('%s.Fields[%d].FieldName', [FExpression, I]))); FValues.Add(Evaluate(Format('%s.Fields[%d].Value', [FExpression, I]))); //** end; if s<> '' then Delete(s, length(s)-4, 5); s := Evaluate(s); s:= Copy(s, 2, Length(s) -2); FFields.CommaText := s; { sw.Stop; s := sw.Elapsed; Application.MessageBox(Pchar(s), '');} end; Now I have no idea how to improve performance.

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• How to temporarily replace one primitive type with another when compiling to different targets in c#

  - by Keith

  How to easily/quickly replace float's for doubles (for example) for compiling to two different targets using these two particular choices of primitive types? Discussion: I have a large amount of c# code under development that I need to compile to alternatively use float, double or decimals depending on the use case of the target assembly. Using something like “class MYNumber : Double” so that it is only necessary to change one line of code does not work as Double is sealed, and obviously there is no #define in C#. Peppering the code with #if #else statements is also not an option, there is just too much supporting Math operators/related code using these particular primitive types. I am at a loss on how to do this apparently simple task, thanks! Edit: Just a quick comment in relation to boxing mentioned in Kyles reply: Unfortunately I need to avoid boxing, mainly since float's are being chosen when maximum speed is required, and decimals when maximum accuracy is the priority (and taking the 20x+ performance hit is acceptable). Boxing would probably rules out decimals as a valid choice and defeat the purpose somewhat. Edit2: For reference, those suggesting generics as a possible answer to this question note that there are many issues which count generics out (at least for our needs). For an overview and further references see Using generics for calculations

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• Passenger: "Missing these required gems redgreen"

  - by Michael Stum

  Hello, total ruby newbie, trying to setup a Rails/MongoDB application on Mac OS X Snow leopard. Installed Ruby 1.9.1 and RubyGems 1.3.7, which ruby and which gem point to the same directory. I'm using the Snow Leopard built-in apache and Passenger 2.2.11. I'm using the rails template from the mongo-site which seems to work okay overall. The exact error that passenger gives me is: /Users/User/Sites/feuerapp/vendor/rails/railties/lib/rails/gem_dependency.rb:119:Warning: Gem::Dependency#version_requirements is deprecated and will be removed on or after August 2010. Use #requirement **Notice: C extension not loaded. This is required for optimum MongoDB Ruby driver performance. You can install the extension as follows: gem install bson_ext If you continue to receive this message after installing, make sure that the bson_ext gem is in your load path and that the bson_ext and mongo gems are of the same version. Missing these required gems: redgreen You're running: ruby 1.9.1.376 at /usr/local/bin/ruby rubygems 1.3.7 at /Users/User/.gem/ruby/1.9.1, /usr/local/lib/ruby/gems/1.9.1 Runrake gems:installto install the missing gems. The weird thing is that redgreen is installed and looks fine to me: Dahlia:feuerapp User$ ls -la vendor/gems/ total 0 drwxr-xr-x 7 User staff 238 May 18 22:56 . drwxr-xr-x 5 User staff 170 May 18 23:00 .. drwxr-xr-x 11 User staff 374 May 18 22:56 factory_girl-1.2.4 drwxr-xr-x 11 User staff 374 May 18 22:56 mocha-0.9.8 drwxr-xr-x 7 User staff 238 May 18 22:56 mongo_mapper-0.7.6 drwxr-xr-x 7 User staff 238 May 18 22:56 redgreen-1.2.2 drwxr-xr-x 11 User staff 374 May 18 22:56 shoulda-2.10.3 Commenting out this line in environment.rb "solves" the issue, but that's not really want I want: config.gem 'redgreen' I don't understand anything of gems yet, but from my limited understanding, redgreen should be there and found?

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• PHP Frameworks: Codeigniter vs. Yii vs. Custom?

  - by Industrial

  Hi everybody, I have used codeigniter for a some years now. Why I chosed to work with codeigniter back then? Pretty much for the extensive documentation that were available and the big user community. It made me as a totally newbie to the MVC pattern able to get a site up and running really fast. I think what is priorited from my side is that the framework doesn't affect performance too much, which Codeigniter seems to be pretty good at (when compared to other frameworks out there) and Yii, an even better option. Since the time has gone from when I started out with codeigniter, the project sizes have also increased and thereby the demand of the framework and it's footprint on the code. I have thought a few times about writing a whole new MVC framework to do only the thing's I want it to do, but it feels like reinventing the wheel and I cannot yet justify it. I am not sure whether or not it's a good solution to build a site that have the potential to become really big on either Yii or Codeigniter. I have tried to find as much as possible documentation about this comparision/issue online before posting here, but have found very few real-life arguments and stories from people that have shifted between the two PHP frameworks or have been in the same situation as me. So - what's your thoughts about Codeigniter vs. Yii vs. going custom? References: http://daniel.carrera.bz/2009/01/comparison-of-php-frameworks-part-i/ http://www.beyondcoding.com/2009/03/02/choosing-a-php-framework-round-2-yii-vs-kohana-vs-codeigniter/

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• Best pattern for storing (product) attributes in SQL Server

  - by EdH

  We are starting a new project where we need to store product and many product attributes in a database. The technology stack is MS SQL 2008 and Entity Framework 4.0 / LINQ for data access. The products (and Products Table) are pretty straightforward (a SKU, manufacturer, price, etc..). However there are also many attributes to store with each product (think industrial widgets). These may range from color to certification(s) to pipe size. Every product may have different attributes, and some may have multiples of the same attribute (Ex: Certifications). The current proposal is that we will basically have a name/value pair table with a FK back to the product ID in each row. An example of the attributes Table may look like this: ProdID AttributeName AttributeValue 123 Color Blue 123 FittingSize 1.25 123 Certification AS1111 123 Certification EE2212 123 Certification FM.3 456 Pipe 11 678 Color Red 999 Certification AE1111 ... Note: Attribute name would likely come from a lookup table or enum. So the main question here is: Is this the best pattern for doing something like this? How will the performance be? Queries will be based on a JOIN of the product and attributes table, and generally need many WHEREs to filter on specific attributes - the most common search will be to find a product based on a set of known/desired attributes. If anyone has any suggestions or a better pattern for this type of data, please let me know. Thanks! -Ed

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• mySQL need to merge fields and get unique rows

  - by jiudev

  i have a database with +1 million rows and the stuktur looks like: CREATE TABLE IF NOT EXISTS `Performance` ( `id` int(11) NOT NULL AUTO_INCREMENT, `CIDs` varchar(100) DEFAULT NULL, `COLOR` varchar(100) DEFAULT NULL, `Name` varchar(255) DEFAULT NULL, `XT` bigint(16) DEFAULT NULL, `MP` varchar(100) DEFAULT NULL, PRIMARY KEY (`id`), KEY `CIDs` (`CIDs`), KEY `COLOR` (`COLOR`), KEY `Name` (`Name`), KEY `XT` (`XT`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=0 ; insert into `Performance` (`id`, `CIDs`, `COLOR`, `Name`, `XT`, `MP`) VALUES (1, '1253374160', 'test test test test test', 'Load1', '89421331221', ''), (2, '1271672029', NULL, 'Load1', '19421331221', NULL), (3, '1188959688', NULL, 'Load2', '39421331221', NULL), (4, '1271672029', NULL, 'Load3', '49421341221', 'Description'), (5, '1271888888', NULL, 'Load4', '59421331221', 'Description'); The Output should look like: +----+------------+--------------------------+-------------+-------------+-------+-----------+---------+ | id | CIDs | COLOR | XT | MP | Name | PIDs | unqName | +----+------------+--------------------------+-------------+-------------+-------+-----------+---------+ | 1 | 1253374160 | test test test test test | 89421331221 | | Load1 | 1,2 | Load1 | | 3 | 1188959688 | NULL | 39421331221 | NULL | Load2 | 3 | Load2 | | 4 | 1271672029 | NULL | 49421341221 | Description | Load3 | 4,5 | Load3 | +----+------------+--------------------------+-------------+-------------+-------+-----------+---------+ any ideas, how i could do this as fast as possible? I have tried with some group by, but it takes some Minutes :/ Thanks Advance //edit: for the solution with the group by, i needed 4 subquerys :/ //edit2: as requested: select id, CIDs, COLOR, XT, MP, Name, concat(PIDs,",",GROUP_CONCAT(DISTINCT id)) as PIDs, IFNULL(Name,id) as unqName from ( select id, CIDs, COLOR, XT, MP, Name, concat(PIDs,",",GROUP_CONCAT(DISTINCT id)) as PIDs, IFNULL(MP,id) as unqMP from ( select id, CIDs, COLOR, XT, MP, Name, concat(PIDs,",",GROUP_CONCAT(DISTINCT id)) as PIDs, IFNULL(XT,id) as unqXT from ( select id, CIDs, COLOR, XT, MP, Name, GROUP_CONCAT(DISTINCT id) as PIDs, IFNULL(COLOR,id) as unqCOLOR from Performance group by unqCOLOR ) m group by unqXT ) x group by unqMP ) y group by unqName

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• choosing row (from group) with max value in a SQL Server Database

  - by sriehl

  I have a large database and am putting together a report of the data. I have aggregated and summed the data from many tables to get two tables that look like the following. id | code | value id | code | value 13 | AA | 0.5 13 | AC | 2.0 13 | AB | 1.0 14 | AB | 1.5 14 | AA | 2.0 13 | AA | 0.5 15 | AB | 0.5 15 | AB | 3.0 15 | AD | 1.5 15 | AA | 1.0 I need to get a list of id's, with the code (sumed from both tables) with the largest value. 13 | AC 14 | AA 15 | AB There are 4-6 thousand records and it is not possible to change the original tables. I'm not too worried about performance as I only need to run it a few times a year. edit: Let me see if I can explain a bit more clearly, imagine the id is the customer id, the code is who they ordered from and the value is how much they spent there. I need a list of the all the customer id's and the store that customer spent the most money at (and if they spent the same at two different stores, put a value such as 'ZZ' in for the store name).

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• Per-pixel per-component alpha blending in Windows

  - by Crend King

  I have a 24-bit bitmaps with R, G, B color channels and a 24-bit bitmap with R, G, B alpha channels. I want to alpha blend the first bitmap to a HDC in GDI or RenderTarget in Direct2D with the alpha channels respectively. For example, suppose for one pixel, the bitmap color is (192, 192, 192), the HDC color is (0, 255, 255) and the alpha channels are (30, 40, 50). The final HDC color should be (22, 245, 242). I know I can BitBlt the HDC to a memory HDC first, do alpha blending by manually calculating the color of each pixel and finally BitBlt back. I just want to avoid the additional blitting and leave APIs do their job (faster since they are in kernel space). The first idea comes to my mind is to split the source bitmap into 3 red-only, green-only and blue-only 8-bit bitmaps, do normal alpha blending, then composite the 3 output bitmaps into the HDC. But I don't find a way to do the splitting and composition natively in Windows (would Direct2D layer help?). Also, the splitting and compositing may require many additional copying. The performance overhead would be too high. Or maybe do the alpha blending in 3 passes. Each pass apply the blending for one channel, while maintaining the other 2 unchanged. Thanks for any comment. EDIT: I found this question, and the answer should be good reference to this problem. However, besides AC_SRC_OVER, there is no other blending operation supported. Why don't Microsoft improve their API?

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• Creating customized .dmg files upon download

  - by Marten

  I want to distribute a cross-platform application for which the executable file is slightly different, depending on the user who downloaded it. This is done by having a placeholder string somewhere in the executable that is replaced with something user-specific upon download. The webserver that has to do these string replacements is a Linux machine. For Windows, the executable is not compressed in the installer .exe, so the string replacement is easy. For uncompressed Mac OS X .dmg files, this is also easy. However, .dmg files that are compressed with either gzip or bzip2 are not so easy. For example, in the latter case, the compressed .dmg is not one big bzip2-compressed disk image, but instead consists of a few different bzip2-compressed parts (with different block sizes) and a plist suffix. Also, decompressing and recompressing the different parts with bzip2 does not result in the original data, so I'm guessing Apple uses some different parameters to bzip2 than the command-line tool. Is there a way to generate a compressed .dmg from an uncompressed one on Linux (which does not have hdiutil)? Or maybe another suggestion for creating customized applications without pregenerating them? It should work without any input by the user.

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• What is more viable to use? Javascript libraries or UI Programming tools?

  - by Haresh Karkar

  What is more viable to use:- Javascript Libraries: YUI, jQuery, ExtJs OR UI Programming tools: GWT, ExtGWT, SmartGWT It has become very difficult to choose between them as they are constantly increasing their capabilities to meet newer requirements. We all know the power of jQuery in UI manipulations. The latest news from Microsoft about jQuery being officially part of .Net developr’s toolkit will definitely make jQuery a preferred choice against other JavaScript libraries [See link: http://weblogs.asp.net/scottgu/archive/2008/09/28/jquery-and-microsoft.aspx]. But on the other hand, GWT is building a framework which could be used on client as well as on the sever side. This is definitely going to make developers’ life easy as it does not require developer to be an expert in browser quirks, XMLHttpRequest, and JavaScript in order to develop high-performance web applications. It includes SDK (Java API libraries, compiler, and development server which allows to write client-side applications in Java and deploy them as JavaScript), Speed Tracer and plug-in for Eclipse. GWT is used by many products like Google Wave and AdWords. So question is still un-answered, what is more viable to use? Any thoughts?

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• C# file write permission issue under "Program Files" folder

  - by George2

  Hello everyone, I am using inno setup to make a installation package for my application, and my application is written by C# + .Net 2.0 + VSTS 2008. Inno setup = http://www.jrsoftware.org/isinfo.php and I install my application under Program Files/Foo folder (Foo is my application name). My application is targeting to Windows Vista. The issue I found is my program cannot write to the folder Program Files/Foo. And I need the permission of write to this folder in order to save some configuration files. The strange thing I notice is the folder Program Files/Foo is marked as readonly and I have checked all folders under Program Files are marked with read only, such as Office. My questions are, Why all folders are marked as read only under Program Files? It means we should not write to individual application folders under Program Files? If not, where should we write information to disk like user last selected configuration information of an individual application? If we could write to individual application folders under Program Files, what is the solution? I do not want my application to Run As administrator to solve this issue, and if there are solution to write to this folder, I want to require minimal permission if possible. thanks in advance, George

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