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  • wpf mvvm datagrid selectedrow

    - by 2Fast4YouBR
    Hi, after some google around, I just figured out that there is no one that is using 100% MvvM pattern to get the ToolKit DataGrid events ! Is that impossible or what ? I see too much people using the code-behind... How can I get the SelectedRow or dblClick events using mvvm ? cheers

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  • What is so bad about Singletons

    - by Ewan Makepeace
    The Singleton pattern is a fully paid up member of the GoF Patterns Book but lately seems rather orphaned by the developer world. I still use quite a lot of singletons, especially for Factory classes, and while you have to be a bit careful about multithreading issues (like any class actually) fail to see why they are so awful. This site especially seems to assume that everyone agrees that Singletons are evil. Why?

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  • With MVVM, does each UI window have its own ViewModel?

    - by j0rd4n
    When I'm designing multiple views under the MVVM pattern, does each view get its own ViewModel or do they all share the same one? I understand that this is ultimately a flexible decision, but what is the best practice? My gut tells me to have a ViewModel for each view (i.e. each separate UI window). All of the blog examples of MVVM show a single view but not much beyond that.

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  • nodejs async.waterfall method

    - by user1513388
    Update 2 Complete code listing var request = require('request'); var cache = require('memory-cache'); var async = require('async'); var server = '172.16.221.190' var user = 'admin' var password ='Passw0rd' var dn ='\\VE\\Policy\\Objects' var jsonpayload = {"Username": user, "Password": password} async.waterfall([ //Get the API Key function(callback){ request.post({uri: 'http://' + server +'/sdk/authorize/', json: jsonpayload, headers: {'content_type': 'application/json'} }, function (e, r, body) { callback(null, body.APIKey); }) }, //List the credential objects function(apikey, callback){ var jsonpayload2 = {"ObjectDN": dn, "Recursive": true} request.post({uri: 'http://' + server +'/sdk/Config/enumerate?apikey=' + apikey, json: jsonpayload2, headers: {'content_type': 'application/json'} }, function (e, r, body) { var dns = []; for (var i = 0; i < body.Objects.length; i++) { dns.push({'name': body.Objects[i].Name, 'dn': body.Objects[i].DN}) } callback(null, dns, apikey); }) }, function(dns, apikey, callback){ // console.log(dns) var cb = []; for (var i = 0; i < dns.length; i++) { //Retrieve the credential var jsonpayload3 = {"CredentialPath": dns[i].dn, "Pattern": null, "Recursive": false} console.log(dns[i].dn) request.post({uri: 'http://' + server +'/sdk/credentials/retrieve?apikey=' + apikey, json: jsonpayload3, headers: {'content_type': 'application/json'} }, function (e, r, body) { // console.log(body) cb.push({'cl': body.Classname}) callback(null, cb, apikey); console.log(cb) }); } } ], function (err, result) { // console.log(result) // result now equals 'done' }); Update: I'm building a small application that needs to make multiple HTTP calls to a an external API and amalgamates the results into a single object or array. e.g. Connect to endpoint and get auth key - pass auth key to step 2 Connect to endpoint using auth key and get JSON results - create an object containing summary results and pass to step 3. Iterate over passed object summary results and call API for each item in the object to get detailed information for each summary line Create a single JSON data structure that contains the summary and detail information. The original question below outlines what I've tried so far! Original Question: Will the async.waterfall method support multiple callbacks? i.e. Iterate over an array thats passed from a previous item in the chain, then invoke multiple http requests each of which would have their own callbacks. e.g, sync.waterfall([ function(dns, key, callback){ var cb = []; for (var i = 0; i < dns.length; i++) { //Retrieve the credential var jsonpayload3 = {"Cred": dns[i].DN, "Pattern": null, "Recursive": false} console.log(dns[i].DN) request.post({uri: 'http://' + vedserver +'/api/cred/retrieve?apikey=' + key, json: jsonpayload3, headers: {'content_type': 'application/json'} }, function (e, r, body) { console.log(body) cb.push({'cl': body.Classname}) callback(null, cb, key); }); } }

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  • Hero Class, php classes

    - by John
    I am going to have different classes for a character that a user play. Like "Mage, Warrior" etc. I am thinking of a method like have some CharacterBase class (abstract?) and then I have a child class which is like WarriorClass or something like that. I think the approach is called Factory pattern or something like that. Anyone got a clue of what I'm trying to achieve here, and are there perhaps any better way to do this?

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  • Multithreading, when to yield versus sleep

    - by aaa
    hello. To clarify terminology, yield is when thread gives up its time slice. My platform of interest is POSIX threads, but I think question is general. Suppose I have consumer/producer pattern. If I want to throttle either consumer or producer, which is better to use, sleep or yield? I am mostly interested in efficiency of using either function. Thanks

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  • Improving MVP in Scala

    - by Alexey Romanov
    The classical strongly typed MVP pattern looks like this in Scala: trait IView { } trait Presenter[View <: IView] { // or have it as an abstract type member val view : View } case class View1(...) extends IView { ... } case object Presenter1 extends Presenter[View1] { val view = View1(...) } Now, I wonder if there is any nice way to improve on it which I am missing...

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  • Dynamically Rendering in a Scrollable Area

    - by James
    What is the generic algorithm or process that is commonly used to dynamically render portions of a scrolling area? For example, in Google Maps, when the user scrolls past the bounds of the currently rendered area, a grey checkerboard pattern is displayed within the not-yet-rendered portions while the application loads and renders those areas. I'm looking specifically for the approach, or the mathematics, related to filling a graphics area in chunks based on what has just come into view. If possible, I'm looking for anything relevant to the GDI+ process of doing so.

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  • why IEEE floating point number calculate exponent using a biased form?

    - by lenatis
    let's say, for the float type in c, according to the IEEE floating point specification, there are 8-bit used for the fraction filed, and it is calculated as first taken these 8-bit and translated it into an unsigned number, and then minus the BIASE, which is 2^7 - 1 = 127, and the result is an exponent ranges from -127 to 128, inclusive. But why can't we just treat these 8-bit pattern as a signed number, since the resulting range is [-128,127], which is almost the same as the previous one.

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  • Using static variables in Android

    - by michael
    Hi, In android, are using static variables a recommended practice? E.g, implementing a Singleton pattern in Java, I usually do: private static A the_instance; public static A getInstance() { if (the_instance == null) { the_instance = new A(); } return the_instance; } Also, when does this get cleaned up by the Android JVM? Thank you.

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  • URL Controller Mapping Strategies (PHP)

    - by sunwukung
    This is kind of an academic question, so feel free to exit now. I've had a dig through Stack for threads pertaining to URL/Controller mapping in MVC frameworks - in particular this one: http://stackoverflow.com/questions/125677/php-application-url-routing So far, I can ascertain two practices: 1: dynamic mapping through parsing the URL string (exploded on '/') 2: pattern matching matching url to config file containing available routes I wanted to get some feedback (or links to some other threads/articles) from folks regarding their views on how best to approach this task.

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  • calling a java servlet from javascript

    - by marco
    Hello, I am trying to create a web application using the MCV design pattern. For the gui part I would like to use javascript. And for the controller Java Servlets. Now I have never really worked with javascript, so I'm having a hard time figuring out how to call a java servlet from javascript and how to get the response from the servlet. Can anybody help me out?

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  • is there a proper way to handle multiple errors/exceptions?

    - by toPeerOrNotToPeer
    in OO programming, is there some conceptual pattern, ideas, about handling multiple errors? for example, i have a method that performs some checks and should return an error message for each error found ['name is too short', 'name contains invalid unicode sequences', 'name is too long'] now, should i use an array of exceptions (not thrown exceptions)? or something like this is better: class MyExceptionList extends Exception{ public Void addException(Exception e){} public Array getExceptions(){} } any theory behind this argument will be appreciated! (this isn't a request about a specific programming language, but a pure theoretical one) thank you in advance

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  • How Do I grep For non-ASCII Characters in UNIX

    - by Peter Conrey
    I have several very large XML files and I'm trying to find the lines that contain non-ASCII characters. I've tried the following: grep -e "[\x{00FF}-\x{FFFF}]" file.xml But this returns every line in the file, regardless of whether the line contains a character in the range specified. Do I have the syntax wrong or am I doing something else wrong? I've also tried: egrep "[\x{00FF}-\x{FFFF}]" file.xml (with both single and double quotes surrounding the pattern).

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  • Delayed instantiation with c# using statment

    - by fearofawhackplanet
    Is there any way to write a using statement without instantiating the IDisposable immediately? For example, if I needed to do something like: using (MyThing thing) { if (_config == null) { thing = new MyThing(); } else { thing = new MyThing(_config); } // do some stuff } // end of 'using' Is there an accepted pattern for cases like this? Or am I back to handling the IDisposable explicitly again?

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  • regex breaks on \n

    - by Sourabh
    hi segmentText = <input from textarea>; testRgx = [/( \d+\.| [^\W\d_]\.|.)+?([!?.?](?= |$)|$)/g]; arrSegments = segmentText.match(testRgx); This expression fails if segmentText has \n or other white spaces in it.I want to add \n in to the list of chars that the above pattern use [!?.?] = [!?.?\n] so that the segment is separated based on the \n character

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  • Refactoring Singleton Overuse

    - by drharris
    Today I had an epiphany, and it was that I was doing everything wrong. Some history: I inherited a C# application, which was really just a collection of static methods, a completely procedural mess of C# code. I refactored this the best I knew at the time, bringing in lots of post-college OOP knowledge. To make a long story short, many of the entities in code have turned out to be Singletons. Today I realized I needed 3 new classes, which would each follow the same Singleton pattern to match the rest of the software. If I keep tumbling down this slippery slope, eventually every class in my application will be Singleton, which will really be no logically different from the original group of static methods. I need help on rethinking this. I know about Dependency Injection, and that would generally be the strategy to use in breaking the Singleton curse. However, I have a few specific questions related to this refactoring, and all about best practices for doing so. How acceptable is the use of static variables to encapsulate configuration information? I have a brain block on using static, and I think it is due to an early OO class in college where the professor said static was bad. But, should I have to reconfigure the class every time I access it? When accessing hardware, is it ok to leave a static pointer to the addresses and variables needed, or should I continually perform Open() and Close() operations? Right now I have a single method acting as the controller. Specifically, I continually poll several external instruments (via hardware drivers) for data. Should this type of controller be the way to go, or should I spawn separate threads for each instrument at the program's startup? If the latter, how do I make this object oriented? Should I create classes called InstrumentAListener and InstrumentBListener? Or is there some standard way to approach this? Is there a better way to do global configuration? Right now I simply have Configuration.Instance.Foo sprinkled liberally throughout the code. Almost every class uses it, so perhaps keeping it as a Singleton makes sense. Any thoughts? A lot of my classes are things like SerialPortWriter or DataFileWriter, which must sit around waiting for this data to stream in. Since they are active the entire time, how should I arrange these in order to listen for the events generated when data comes in? Any other resources, books, or comments about how to get away from Singletons and other pattern overuse would be helpful.

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  • How to completely ignore linkbreak and tab in RegEx?

    - by Kthurein
    Hi, Is there any way to completely ignore link break and tab characters etc. in RegEx? For instance, the line break and tab characters could be found anywhere and in any order in the content string. ... [CustomToken \t \r\n Type="" \t \r\n Property="" \n /] ... [CT ... The is the RegularExpression that I am currently using: (\[CustomToken).*?(\/\]) .NET API Regex.Matches(string input, string pattern) Thanks for your suggestion.

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  • Web user interface. Add new item and list of items

    - by w1z
    Hello all I need your opinion on the following question. It's need to implement the administration web interface to add\change\remove\display system users. I need to display all users and controls for user adding/changing. What is the common pattern in web for this situation: create one page or create two separate pages for displaying and adding/changing users? Thanks, sorry for some possible oddness (:

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  • Is there a more modern regexp handler for Open Object Rexx

    - by Brent.Longborough
    The regular expression class (rxregexp.dll) that comes with ooRexx (I'm on 4.0.0) is relatively low on function compared, say, with Python's re module (even at 2.5.2). It appears to have no assertions, no facilities for group extraction, or for substitution. Greedy or lazy matching is a global pattern option, rather than flagged by an additional "?". Basically, a pre-PCRE regular expression engine. Does anyone know if anything with more up-to-date function is available?

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