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Search found 1086 results on 44 pages for 'representation'.

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• How do I maintain coherency between model and view-model in MVVM pattern?

  - by Mike Garrett

  Problem Statement I'm writing a very basic WPF application to alter the contents of a configuration file. The data format is an XML file with a schema. I want to use it as a learning project for MVVM, so I have duly divided the code into Model: C# classes auto-generated from xsd.exe View-Model: View-friendly representation of the Model. View: Xaml and empty code behind I understand how the View-Model can make View-binding a breeze. However, doesn't that leave the View-Model <- Model semantics very awkward? Xsd.exe generates C# classes with arrays for multiple XML elements. However, at the V-VM level you need Observable Collections. Questions: Does this really mean I have to keep two completely different collection types representing the same data in coherence? What are the best practices for maintaining coherence between the Model and the View-Model?

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• Libraries/Solutions for using XSL to create interactive web forms from XML

  - by Brabster

  This seems like a pretty straightforward thing to do, but I can't find anything off the open-source shelf. Is there a solution already out there that does the following: can be configured with an arbitrary XSL stylesheet generates a web form based on an arbitrary XML document and the XSL creates edit functionality in appropriate places in the rendered form updates the local representation of the XML document provides capabilities to view, save the new XML document Ideally, one that plugs into a Java web application. Even better if it can generate the XSL based on schema documents - but that might not be feasible, not really thought it through. For context, I'm thinking things like pleasant-for-humans editing of Maven POMs, ANT build.xml, etc. Cheers,

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• Expression Tree : C#

  - by nettguy

  My understanding of expression tree is : Expression trees are in-memory representation of expression like arithmetic or boolean expression.The expressions are stored into the parsed tree.so we can easily transalate into any other language. Linq to SQL uses expression tree.Normally when our LINQ to SQL query compiler translates it to parsed expression trees.These are passed to Sql Server as T-SQL Statements.The Sql server executes the T-SQL query and sends down the result back.That is why when you execute LINQ to SQL you gets IQueryable<T> not IEnumetrable<T>.Because IQuerybale contains public IQueryable:IEnumerable { Type Element {get;} Expression Expression {get;} IQueryaleProvider Provider {get;} } Questions : Microsoft uses Expression trees to play with LINQ-to-Sql.What are the different ways can i use expression trees to boost my code. Apart from LINQ to SQL,Linq to amazon ,who used expression trees in their applications? Linq to Object return IEnumerable,Linq to SQL return IQueryable ,What does LINQ to XML return?

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• Testing perceived performance

  - by Josh Kelley

  I recently got a shiny new development workstation. The only disadvantage of this is that the desktop apps I'm developing now run very, very fast, and so I fear that parts of the code that would be annoyingly slow on end users' machines will go unnoticed during my testing. Is there a good way to slow down an application for testing? I've tried searching around, but all of the results I've been able to find seem pretty fiddly to set up (e.g., manually setting up a high-priority CPU-bound task on the same CPU core as the target app, or running a background process that rapidly interrupts and resumes the target app), and I don't know if the end result is actually a good representation of running on a slower computer (with its slower CPU, slower RAM, slower disk I/O...). I don't think that this is a job for a profiler; I'm interested in the user's perception of end-to-end performance rather than in where the time goes for particular operations.

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• Double Negation in C++ code.

  - by Brian Gianforcaro

  I just came onto a project with a pretty huge code base. I'm mostly dealing with C++ and a lot of the code they write uses double negation for their boolean logic. if (!!variable && (!!api.lookup("some-string"))) { do_some_stuff(); } I know these guys are intelligent programmers, it's obvious they aren't doing this by accident. I'm no seasoned C++ expert, my only guess at why they are doing this is that they want to make absolutely positive that the value being evaluated is the actual boolean representation. So they negate it, then negate that again to get it back to its actual boolean value. Is this a correct? or am I missing something else? Thanks, Brian Gianforcaro

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• What exactly is REST architecture and how is it implemented in Rails?

  - by Jagira

  This is what I think of REST architecture. For every resource, there is an unique URI. We can manipulate that object using its URI and HTTP actions [POST, GET, PUT and DELETE]. The HTTP request transfers the representation of the state of that object. In all the texts I have read, REST is explained in a weird and confusing manner. One more thing, RESTFUL implementation in rails produces different urls for different purposes. Like /teams - for 'index' method... /teams/new - for 'new' method and so on. Ain't this moving away from rest, which defines that each resource has one unique URI???

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• Python Imaging: YCbCr problems

  - by daver

  Hi, I'm doing some image processing in Python using PIL, I need to extract the luminance layer from a series of images, and do some processing on that using numpy, then put the edited luminance layer back into the image and save it. The problem is, I can't seem to get any meaningful representation of my Image in a YCbCr format, or at least I don't understand what PIL is giving me in YCbCr. PIL documentation claims YCbCr format gives three channels, but when I grab the data out of the image using np.asarray, I get 4 channels. Ok, so I figure one must be alpha. Here is some code I'm using to test this process: import Image as im import numpy as np pengIm = im.open("Data\\Test\\Penguins.bmp") yIm = pengIm.convert("YCbCr") testIm = np.asarray(yIm) grey = testIm[:,:,0] grey = grey.astype('uint8') greyIm = im.fromarray(grey, "L") greyIm.save("Data\\Test\\grey.bmp") I'm expecting a greyscale version of my image, but what I get is this jumbled up mess: http://i.imgur.com/zlhIh.png Can anybody explain to me where I'm going wrong? The same code in matlab works exactly as I expect.

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• NSBitmapImageRep data Format as application icon image??

  - by Joe

  i have a char* array of data that was in RGBA and then moved to ARGB Bottom line is the set application image looks totally messed up and i cant put my finger on why? //create a bitmap representation of the image data. //The data is expected to be unsigned char** NSBitmapImageRep *bitmap = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes : (unsigned char**) &dest pixelsWide:width pixelsHigh:height bitsPerSample:8 samplesPerPixel:4 hasAlpha:YES isPlanar:NO colorSpaceName:NSDeviceRGBColorSpace bitmapFormat:NSAlphaFirstBitmapFormat bytesPerRow: 0 bitsPerPixel:0 ]; NSImage *image = [[NSImage alloc] initWithSize:NSMakeSize(width, height)]; [image addRepresentation:bitmap]; if( image == NULL) { printf("image is null\n"); fflush(stdout); } [NSApp setApplicationIconImage :image]; What in these values is off? the image looks very multicolored and pixelated, with transparent parts/lines as well.

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• Most efficient way to save tile data of an isometric game

  - by Harmen

  Hello, I'm working on an isometric game for fast browsers that support <canvas>, which is great fun. To save information of each tile, I use a two-dimensional array which contains numbers representing a tile ID, like: var level = [[1, 1, 1, 2, 1, 0], [0, 1, 1, 2, 0, 1], [0, 1, 1, 2, 1, 1]]; var tiles = [ {name: 'grass', color: 'green'}, {name: 'water', color: 'blue'}, {name: 'forest', color: 'ForestGreen'} ]; So far it works great, but now I want to work with heights and slopes like in this picture: For each tile I need to save it's tile ID, height and information about which corners are turned upward. I came up with a simple idea about a bitwise representation of all four corners, like this: 1011 // top, bottom and left corner turned up My question is: what is the most efficient way to save these three values for each cell? Is it possible to save these three values as one integer?

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• Zend Dd Rowset getting parent row

  - by simple

  I am wondering about using the abstraction in Zend Db RowSet instead of joins, is it possible for instance I am able to get some info from parent table as in here /** * Get default photo info (path , description) */ public function getDefaultPhotoInfo($userdId){ $select = $this->select($this) ->where('id=?', $userdId); $rowset = $this->fetchAll($select); $current = $rowset->current(); $res = $current->findParentRow('UserPhotos', 'Avatar'); if(isset($res)){ return $res->toArray(); } } How can I use Rowset abstraction to get this logic working table( id, pic_path,) table_translation(id, table_id, lang_id, pic_title); the above is representation of two tables , the idea is to get the info from both table specifying the lang_id , it is easy with joins but can I do it with the abstraction of Db Rowset ?

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• Fastest way to display a full calendar

  - by Aurélien Ribon

  Hello, I need to display a complete calendar (12 months, 31~ days/month) on screen. Currently, I'm using a 12-column grid, with each column filled with a "months" stackpanel. Each "month" stackpanel is filled with 31 (or less) day representations. Each day representation is composed of a DockPanel embedding three controls : a textblock to display the day letter a textblock to display the day number a textblock to display a short message Of course, performances are crushed down when I try to resize the window. Is there a useful trick to allow a fast display of many textblocks ?

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• [Sql-Server]what data type to use for password salt and hash values and what length?

  - by Pandiya Chendur

  I am generating salt and hash values from my passwords by using, string salt = CreateSalt(TxtPassword.Text.Length); string hash = CreatePasswordHash(TxtPassword.Text, salt); private static string CreateSalt(int size) { //Generate a cryptographic random number. RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); byte[] buff = new byte[size]; rng.GetBytes(buff); // Return a Base64 string representation of the random number. return Convert.ToBase64String(buff); } private static string CreatePasswordHash(string pwd, string salt) { string saltAndPwd = String.Concat(pwd, salt); string hashedPwd = FormsAuthentication.HashPasswordForStoringInConfigFile( saltAndPwd, "sha1"); return hashedPwd; } What datatype you would suggest for storing these values in sql server? Any suggestion... Salt:9GsPWpFD Hash:E778AF0DC5F2953A00B35B35D80F6262CDBB8567

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• Encoding a string as an integer .NET

  - by Paul Knopf

  I have a string that I would like represented uniquely as an integer. For example: A3FJEI = 34950140 How would I go about writing a EncodeAsInteger(string) method. I understand that the amount of characters in the string will make the integer increase greatly, forcing the value to become a long, not an int. Since I need the value to be an integer, I don't need the numerical representation to be entirely unique to the string. Maybe I can foreach through all the characters of the string and sum the numerical keycode of the character.

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• Socket programming and telnet with VB.net

  - by Mike

  I'm writing a GUI-based app in VB.net that talks to a LambdaMOO server via telnet, sends commands to display the object hierarchy, then parses the output and creates a visual representation of the object hierarchy. So my question is: is there some kind of "telnet client" class for .NET to simplify the sending and receiving of data, or do I have to write my own using the socket API? Does Mono have something like this? Barring an easy solution, does anyone have a good tutorial they can point to for telnet client programming in VB.net?

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• Using LinqSql, stored procedure returns datatype image problem

  - by Elias

  Hello! I´ve got a problem when using LINQ to execute a stored procedure and return its values. One of the column that the stored procedure returns is of datatype image and contains a pdf in binary form.(this because the database is deployed on sql server 2000, otherwised i would choose a blob) When including the stored procedure in my linq class its generates that my pdf columns is datatype int in the designer class. I´ve work around the problem and manually changed the datatype in representation of the stored procedure in the designer class. But when adding/removing items in the linq class the designer file re-generates and my changes are lost. Are there any better solution for my problem??

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• Perl, treat string as binary byte array

  - by Mike

  In Perl, is it appropriate to use a string as a byte array containing 8-bit data? All the documentation I can find on this subject focuses on 7-bit strings. For instance, if I read some data from a binary file into $data my $data; open FILE, "<", $filepath; binmode FILE; read FILE $data 1024; and I want to get the first byte out, is substr($data,1,1) appropriate? (again, assuming it is 8-bit data) I come from a mostly C background, and I am used to passing a char pointer to a read() function. My problem might be that I don't understand what the underlying representation of a string is in Perl.

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• Enums and Annotations

  - by PeterMmm

  I want to use an Annotation in compile-safe form. To pass the value() to the Annotation i want to use the String representation of an enum. Is there a way to use @A with a value from enum E ? public class T { public enum E { a,b; } // C1: i want this, but it won't compile @A(E.a) void bar() { // C2: no chance, it won't compile @A(E.a.toString()) void bar2() { } // C3: this is ok @A("a"+"b") void bar3() { } // C4: is constant like C3, is'nt it ? @A(""+E.a) void bar4() { } } @interface A { String value(); }

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• Decorator for determining HTTP response from a view

  - by polera

  I want to create a decorator that will allow me to return a raw or "string" representation of a view if a GET parameter "raw" equals "1". The concept works, but I'm stuck on how to pass context to my renderer. Here's what I have so far: from django.shortcuts import render_to_response from django.http import HttpResponse from django.template.loader import render_to_string def raw_response(template): def wrap(view): def response(request,*args,**kwargs): if request.method == "GET": try: if request.GET['raw'] == "1": render = HttpResponse(render_to_string(template,{}),content_type="text/plain") return render except Exception: render = render_to_response(template,{}) return render return response return wrap Currently, the {} is there just as a place holder. Ultimately, I'd like to be able to pass a dict like this: @raw_response('my_template_name.html') def view_name(request): render({"x":42}) Any assistance is appreciated.

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• Delphi: how to efficently read a big binary file, converting it to hexadecimal for passing it as a v

  - by user193655

  I need to convert a binary file (a zip file) into hexadecimal representation, to then send it to sql-server as a varbinary(max) function parameter. A full example (using a very small file!) is: 1) my file contains the following bits 000011110000111 2) I need a procedure to QUICKLY convert it to 0F0F 3) I will call a sql server function passing 0x0F0F as parameter The problem is that I have large files (up to 100MB, even if average file size is 100KB files are possible), so I need the fastest way to do this. Otherwise stated: I need to create the string '0x'+BinaryDataInHexadecimalRepresentation in the most efficient way. Related question: passing hexadecimal data to sql server

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• Any reason not to always log stack traces?

  - by Chris Knight

  Encountered a frustrating problem in our application today which came down to an ArrayIndexOutOfBounds exception being thrown. The exception's type was just about all that was logged which is fairly useless (but, oh dear legacy app, we still love you, mostly). I've redeployed the application with a change which logs the stack trace on exception handling (and immediately found the root cause of the problem) and wondered why no one else did this before. Do you generally log the stack trace and is there any reason you wouldn't do this? Bonus points if you can explain (why, not how) the rationale behind having to jump hoops in java to get a string representation of a stack trace!

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• Nhibernate ValueType Collection as delimited string in DB

  - by JWendel

  Hi I have a legacy db that I am mapping with Nhibernate. And in several locations a list och strigs or domain objects are mapped as a delimited string in the database. Either 'string|string|string' in the value type cases and like 'domainID|domainID|domainID' in the references type cases. I know I can create a dummy property on the class and map to that fields but I would like to do it in a more clean way, like when mapping Enums as their string representation with the EnumStringType class. Is a IUserType the way to go here? Thanks in advance /Johan

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• Undetermined type conversion in VB.NET 2008

  - by user337501

  I figured this would be a quick google, but extensive searching hasnt yielded any results. Everything about type conversion seems to dance around this concept. I want to get the type of variable "a", and make a new variable named "b" of that type. Otherwise I could have "a" as a type already declared and "b" simply as an Object, then try to cast "b" to the type of "a". Dim a As Integer Dim b As Whatever a Is OR TryCast(b, Whatever a Is) I would also like to make the conversion using a variable representation of the type, but cant find info on how to do that either. Sorta like: Dim a As Integer Dim b As Object Dim t As Type t = a.GetType() TryCast(b, t) Realizing I'm completely misusing TryCast here, I'm mostly trying to get my goal across. I figured it would be an easy quick thing to do but I cant really find any specific info on it. Any ideas?

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• Avoid hourglass mouse cursor when calling a web-service?

  - by BigMoose

  I don't know if this is a general web-services issue or just my specific scenario, which is a WPF application with a DispatcherTimer calling a web-service method. Whenever the timer is called, the mouse cursor automatically changes to an hourglass cursor. The processing of the call is very short and happens every 3 seconds, so the user experience is that every 3 seconds the mouse filckers as an hourglass for a split-second and then goes back to the normal cursor representation. How can I avoid this inconvenience? Thanks.

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• What to store at application Settings, numeric / string representations or objects?

  - by SoMoS

  Hello, I've been thinking for a while on what to store at the Project Settings, objects or numeric/string representations of those objects to set a rule and avoid thinking on this at the future so I want to take the best approach. On one side storing object representations grants you that what is stored is valid and saves you from doing conversions each time you access them. You only need objects with the attribute. At the other side storing the numeric/string representation of an object eases the editing of the setting because at the end the user will be entering numeric or string information. What do you do with this issue?

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• How to use QMetaMethod with QObject::connect

  - by VestniK

  I have two instances of QObject subclasses and two QMetaMethod instances of signal in one of objects and slot in another object. I want to connect this signal and slot with each other. I've looked through the qobject.h file and find that SIGNAL() and SLOT() macro are just add "1" or "2" character to the beginning of method signature so it looks like it should be possible to add the same character to the beginning of string returned by QMetaMethod::signature() but this approach depends on some undocumented internals of toolkit and may be broken at any time by a new version of Qt. Does anybody know reliable way to connect signals and slots through their QMetaMethod reflection representation?

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