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• how to implement login and service features as in skype or msn chat in a wpf application

  - by black sensei

  Hello Good people! I'm building an WPF application that connect to web services for its operations.Things that i needed to be working are so far fine.Now i'll like to improve use experience by adding features like username editable combobox, sign me in when skype start and start when computer start. I have a fair idea about each feature but very small knowledge about their implementation. Question 1 username combobox : i use a combobox with isEditable set to true but i think it doesnt have the previous username, would that mean that i have to store every successful login username in a sqlite for example? Question 2 sign me in when skype start : i think about using sqlite after all to store the credentials and store the value (as in true or false) if autologin has to be performed. Question 3 start when computer start : i know it's about having is as service.but the process of using it as a service and removing its service when checkbox is checked or unckecked is a bit confusing to me. Question 4 Please wait(signing in) of skype if i want to do things like please wait at login(login is over webservice) in a WPF application should i use a animated gif in a grid that i can show when hiding the login combobox and passwordbox grid or i should use an animated object(for which i have no knowledge about for now) ? This post in mainly for you experts to either point me to the right resource and tell me what is done as best practice. things like dos and dons.Thanks for reading this and please let me have a clair idea about how to start implementing those features. thanks again

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• Best Pattern for AllowUnsafeUpdates

  - by webwires

  So far, in my research I have seen that it is unwise to set AllowUnsafeUpdates on GET request operation to avoid cross site scripting. But, if it is required to allow this, what is the proper way to handle the situation to mitigate any exposure? Here is my best first guess on a reliable pattern if you absolutely need to allow web or site updates on a GET request. Best Practice? protected override void OnLoad(System.EventArgs e) { if(Request.HttpMethod == "POST") { SPUtility.ValidateFormDigest(); // will automatically set AllowSafeUpdates to true } // If not a POST then AllowUnsafeUpdates should be used only // at the point of update and reset immediately after finished // NOTE: Is this true? How is cross-site scripting used on GET // and what mitigates the vulnerability? } // Point of item update SPSecurity.RunWithElevatedPrivledges(delegate() { using(SPSite site = new SPSite(SPContext.Current.Site.Url)) { using (SPWeb web = site.RootWeb) { bool allowUpdates = web.AllowUnsafeUpdates; //store original value web.AllowUnsafeUpdates = true; //... Do something and call Update() ... web.AllowUnsafeUpdates = allowUpdates; //restore original value } } }); Feedback on the best pattern is appreciated.

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• Explaining the need to avoid horizontal scroll

  - by Bradley Herman

  I need help explaining to my boss why her design is poor on a client's website. She has no knowledge of the web, and it can be difficult as a web developer working with a woman who is a graphic designer (not even a web designer really). On a current site she has designed, an image bar "needs" to be ~1200px according to her, though it isn't necessary with the content. A quick sketch to illustrate what's going on: As you see, the banner spills out past the 960px of the content and as wide as 1200px. This creates a horizontal scroll when all the content is viewable within the 960px wide viewport. I need to make this an <img and not a CSS background because it's a jQuery slideshow that fades from image to image. I think this is a big problem because a lot of people are going to get a horizontal scroll bar imposed in their browser when they're still able to see all the relevant content. She thinks no one will notice and it'll be fine; I think it's very bad practice and confusing to the end user. How do I explain the problem to her?

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• How do you think while formulating Sql Queries. Is it an experience or a concept ?

  - by Shantanu Gupta

  I have been working on sql server and front end coding and have usually faced problem formulating queries. I do understand most of the concepts of sql that are needed in formulating queries but whenever some new functionality comes into the picture that can be dont using sql query, i do usually fails resolving them. I am very comfortable with select queries using joins and all such things but when it comes to DML operation i usually fails For every query that i never done before I usually finds uncomfortable with that while creating them. Whenever I goes for an interview I usually faces this problem. Is it their some concept behind approaching on formulating sql queries. Eg. I need to create an sql query such that A table contain single column having duplicate record. I need to remove duplicate records. I know i can find the solution to this query very easily on Googling, but I want to know how everyone comes to the desired result. Is it something like Practice Makes Man Perfect i.e. once you did it, next time you will be able to formulate or their is some logic or concept behind. I could have get my answer of solving above problem simply by posting it on stackoverflow and i would have been with an answer within 5 to 10 minutes but I want to know the reason. How do you work on any new kind of query. Is it a major contribution of experience or some an implementation of concepts. Whenever I learns some new thing in coding section I tries to utilize it wherever I can use it. But here scenario seems to be changed because might be i am lagging in some concepts.

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• Sharepoint BDC Error: The title property of entity tblStaff is set to an invalid value

  - by Christopher Rathermel

  I am just starting to create our Business Data Catalog(s) for our practice management system and I am running into an issue w/ our staff table. Background: I am using Business Data Catalog Definition Editor to create my ADF. I am using the RevertToSelf Authentication Mode. I have tried a few other tables and they seem to work just fine thus far.. only issue is w/ the staff table. If I removed all the columns for the staff entity except the ID and a few columns for the name it actually works. So it has a problem w/ one of my columns in tblStaff. I receive this error even when I set up an ADF w/ just this one entity. So w/ no associations.. When attempting to view the record: http://servername/ssp/admin/Content/tblstaff.aspx?StaffID={0} w/ {0} replaced w/ an actual staff ID I get the following error: The title property of entity tblStaff is set to an invalid value. Things I have tried: I noticed that I do have a column in my staff table called "Title" and removed it from ADF w/ no luck... Same error.. I tried to use bdc meta man to create my ADF and I got the same error... Any ideas? Chris

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• What's the best way to develop a debugging window for an ajax ASP.Net MVC application

  - by KallDrexx

  While developing my ASP.NET MVC, I have started to see the need for a debugging console window to assist in figuring out what is going right and wrong in my code. I read the last few chapters of the Pro Asp.net MVC book, and the author details how to use http modules to show page load/creation times and linq to sql query logs, both of which I definitely want to be able to see. However, since I am loading a lot of small sections of my page individually with ajax I don't want the debug information right there in the middle of my screen. So the idea I came up with was to have a separate browser window (open-able by a link or some javascript) with a console log, that can contain logged entries both from javascript and from the asp.net mvc run. The former should be relatively easy, but I'm having trouble coming up with a way to log the asp.net information in ajax requests. The direction I have been thinking of going is to create an httpmodule (like the Pro MVC book does), and have that module contain some that append the javascript's log to console calls with the messages. The issue I see with this is finding a way to get the log messages from the controller's action methods to the httpmodule's methods. The only way I see to do this is with a singleton, but I'm not sure if singletons are bad practice for a stateless web application. Furthermore, it seems like if I return json with my ajax calls (instead of pure html) then that won't work at all anyways and unless there is a way to add data to an existing json structure inside the httpmodule. How does everyone else handle this type of debugging in heavily ajax applications? For reference, the javascript library I am using is jquery.

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• Python Locking Implementation (with threading module)

  - by Matty

  This is probably a rudimentary question, but I'm new to threaded programming in Python and am not entirely sure what the correct practice is. Should I be creating a single lock object (either globally or being passed around) and using that everywhere that I need to do locking? Or, should I be creating multiple lock instances in each of the classes where I will be employing them. Take these 2 rudimentary code samples, which direction is best to go? The main difference being that a single lock instance is used in both class A and B in the second, while multiple instances are used in the first. Sample 1 class A(): def __init__(self, theList): self.theList = theList self.lock = threading.Lock() def poll(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.append(something) finally: self.lock.release() class B(threading.Thread): def __init__(self,theList): self.theList = theList self.lock = threading.Lock() self.start() def run(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.remove(something) finally: self.lock.release() if __name__ == "__main__": aList = [] for x in range(10): B(aList) A(aList).poll() Sample 2 class A(): def __init__(self, theList,lock): self.theList = theList self.lock = lock def poll(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.append(something) finally: self.lock.release() class B(threading.Thread): def __init__(self,theList,lock): self.theList = theList self.lock = lock self.start() def run(self): while True: # do some stuff that eventually needs to work with theList self.lock.acquire() try: self.theList.remove(something) finally: self.lock.release() if __name__ == "__main__": lock = threading.Lock() aList = [] for x in range(10): B(aList,lock) A(aList,lock).poll()

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• Remaking this loop by user?

  - by Elliot

  I'm wondering if theres a best practice for what I'm trying to accomplish... First we have the model categories, categories, has_many posts. Now lets say, users add posts. Now, I have a page, that I want to display only the current user's posts by category. Lets say we have the following categories: A, B, and C User 1, has posted in Categories A and B. In my view I have something like: <% @categories.select {|cat| cat.posts.count > 0}.each do |category| %> <%= category.name %><br/> <% category.posts.select {|post| post.user == current_user}.each do |post| %> <%= post.content %><br/> <% end %> <% end %> For the most part its almost there. The issue is, it will still show an empty category if any posts have been entered in it at all (even if the current user has not input posts into that category. So the question boils down to: How do I make the following loop only count posts in the category from the current user? <% @categories.select {|cat| cat.posts.count 0}.each do |category| % Best, Elliot

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• How do I pass a const reference in C#?

  - by Maciek

  In C++, passing const references is a common practice - for instance : #include <iostream> using namespace std; class X { public : X() {m_x = 0; } X(const int & x) {m_x = x; } X(const X & other) { *this = other; } X & operator = (const X & other) { m_x = other.m_x; return *this; } void print() { cout << m_x << endl; } private : int m_x; }; void main() { X x1(5); X x2(4); X x3(x2); x2 = x1; x1.print(); x2.print(); x3.print(); } This very simple example illustrates how it's done - pretty much. However I've noticed that in C# this doesn't seem to be the case. Do I have to pass const references in C# ? what do I need the "ref" keyword for? Please note that I know and understand what C# reference and value types are.

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• Design considerations for temporarily transforming a player into an animal in a role playing game

  - by mikedev

  I am working on a role playing game for fun and to practice design patterns. I would like players to be able to transform themselves into different animals. For example, a Druid might be able to shape shift into a cheetah. Right now I'm planning on using the decorator pattern to do this but my question is - how do I make it so that when a druid is in the cheetah form, they can only access skills for the cheetah? In other words, they should not be able to access their normal Druid skills. Using the decorator pattern it appears that even in the cheetah form my druid will be able to access their normal druid skills. class Druid : Character { // many cool druid skills and spells void LightHeal(Character target) { } } abstract class CharacterDecorator : Character { Character DecoratedCharacter; } class CheetahForm : CharacterDecorator { Character DecoratedCharacter; public CheetahForm(Character decoratedCharacter) { DecoratedCharacter= decoratedCharacter; } // many cool cheetah related skills void CheetahRun() { // let player move very fast } } now using the classes Druid myDruid = new Druid(); myDruid.LightHeal(myDruid); // casting light heal here is fine myDruid = new CheetahForm(myDruid); myDruid.LightHeal(myDruid); // casting here should not be allowed Hmmmm...now that I think about it, will myDruid be unable to us the Druid class spells/skills unless the class is down-casted? But even if that's the case, is there a better way to ensure that myDruid at this point is locked out from all Druid related spells/skills until it is cast back to a Druid (since currently it's in CheetahForm)

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• Is an "infinite" iterator bad design?

  - by Adamski

  Is it generally considered bad practice to provide Iterator implementations that are "infinite"; i.e. where calls to hasNext() always(*) return true? Typically I'd say "yes" because the calling code could behave erratically, but in the below implementation hasNext() will return true unless the caller removes all elements from the List that the iterator was initialised with; i.e. there is a termination condition. Do you think this is a legitimate use of Iterator? It doesn't seem to violate the contract although I suppose one could argue it's unintuitive. public class CyclicIterator<T> implements Iterator<T> { private final List<T> l; private Iterator it; public CyclicIterator<T>(List<T> l) { this.l = l; this.it = l.iterator(); } public boolean hasNext() { return !l.isEmpty(); } public T next() { T ret; if (!hasNext()) { throw new NoSuchElementException(); } else if (it.hasNext()) { ret = it.next(); } else { it = l.iterator(); ret = it.next(); } return ret; } public void remove() { it.remove(); } }

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• Using git pull to track a remote branch without merging

  - by J Barlow

  I am using git to track content which is changed by some people and shared "read-only" with others. The "readers" may from time to time need to make a change, but mostly they will not. I want to allow for the git "writers" to rebase pushed branches** if need be, and ensure that the "readers" never accidentally get a merge. That's normally easy enough. git pull origin +master There's one case that seems to cause problems. If a reader makes a local change, the command above will merge. I want pull to be fully automatic if the reader has not made local changes, while if they have made local changes, it should stop and ask for input. I want to track any upstream changes while being careful about merging downstream changes. In a way, I don't really want to pull. I want to track the master branch exactly. ** (I know this is not a best practice, but it seems necessary in our case: we have one main branch that contains most of the work and some topic branches for specific customers with minor changes that need to be isolated. It seems easiest to frequently rebase to keep the topics up to date.)

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• Using $.get with jquery validation

  - by Jimmy McCarthy

  I'm trying to use the Jquery builtin validator on my page. The issue is that I have certain fields that only are required if the JobID (entered into another field) does not already exist in our database. I have a simple service which simply takes JobID and returns True or False based on whether the JobID exists, but I can't seem to get this information where I want it. Some sample code: $("#dep_form").validate({ rules: { JobID: { required: true, digits: true, minlength: 3 }, OrgName: { required: function(element) { //This field is required if the JobID is new. return $("#jobinfo").html().length==15; } } }, messages: { JobID: { required: "Enter a Job Number.", digits: "Only numbers are allowed in Job ID's.", minlength: "Job Number must be at least 3 digits" }, OrgName: { required: "Select a Practice from the dropdown list." } }, errorClass: "ui-state-error-input", errorLabelContainer: "#errorbox", errorElement: 'li', errorContainer: "#validation_errors", onfocusout: false, onkeyup: false, focusinvalid: false }; Currently, I'm using a lazy method to validate (shown above). However, I now have access to a service using the URL: var lookupurl = "/deposits/jobidvalidate/?q=" + $("#id_JobID").val() + "&t=" + new Date().getTime(); which is a page which will contain just the word True or False based on whether that given JobID exists. I've tried half a dozen different ways of setting variables and calling functions within functions and still cannot get a way to simply return the value of that page (which I've been trying to access with $.get() ) to my validator, so that required is set to true when the Job does not exist and false if the job already exists. Any suggestions? Thanks.

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• How to not pass around the container when using IoC in Winforms

  - by L2Type

  I'm new to the world of IoC and having a problem with implementing it in a Winforms application. I have an extremely basic application Winform application that uses MVC, it is one controller that does all the work and a working dialog (obviously with a controller). So I load all my classes in to my IoC container in program.cs and create the main form controller using the container. But this is where I am having problems, I only want to create the working dialog controller when it's used and inside a using statement. At first I passed in the container but I've read this is bad practice and more over the container is a static and I want to unit test this class. So how do you create classes in a unit test friendly way without passing in the container, I was considering the abstract factory pattern but that alone would solve my problem without using the IoC. I'm not using any famous framework, I borrowed a basic one from this blog post http://www.kenegozi.com/Blog/2008/01/17/its-my-turn-to-build-an-ioc-container-in-15-minutes-and-33-lines.aspx How do I do this with IoC? Is this the wrong use for IoC?

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• Version control - stubs and mocks

  - by Tesserex

  For the sake of this question, I don't care about the difference between stubs, mocks, dummies, fakes, etc. Let's say I'm working on a project with one other person. I'm working on component A and he is working on component B. They work together, so I stub out B for testing, and he stubs out A. We're working in a DVCS, let's say Git, because that's actually the case here. When it comes time to merge our components together, we need to get the "real" files from my A and his B, but throw away all the fake stuff. During development, it's likely (unless I need to learn how to properly stub things) that the fakes have the same file names and class names as the real thing. So my question is: what is the proper procedure for doing version control on the fakes, and how are the components correctly merged, making sure to grab the real thing and not the fake? I would guess that one way is just do the merge, expect it to say CONFLICT, and then manually delete all the fake code out of the half-merged files. But this sounds tedious and inefficient. Should the fake things not go under VC at all? Should they be ripped out just before merging? Sorry if the answer to this should be obvious or trivial, I'm just looking for a "suggested practice" here.

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• autocommit and @Transactional and Cascading with spring, jpa and hibernate

  - by subes

  Hi, what I would like to accomplish is the following: have autocommit enabled so per default all queries get commited if there is a @Transactional on a method, it overrides the autocommit and encloses all queries into a single transaction, thus overriding the autocommit if there is a @Transactional method that calls other @Transactional annotated methods, the outer most annotation should override the inner annotaions and create a larger transaction, thus annotations also override eachother I am currently still learning about spring-orm and couldn't find documentation about this and don't have a test project for this yet. So my questions are: What is the default behaviour of transactions in spring? If the default differs from my requirement, is there a way to configure my desired behaviour? Or is there a totally different best practice for transactions? --EDIT-- I have the following test-setup: @javax.persistence.Entity public class Entity { @Id @GeneratedValue private Integer id; private String name; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } @Repository public class Dao { @PersistenceContext private EntityManager em; public void insert(Entity ent) { em.persist(ent); } @SuppressWarnings("unchecked") public List<Entity> selectAll() { List<Entity> ents = em.createQuery("select e from " + Entity.class.getName() + " e").getResultList(); return ents; } } If I have it like this, even with autocommit enabled in hibernate, the insert method does nothing. I have to add @Transactional to the insert or the method calling insert for it to work... Is there a way to make @Transactional completely optional?

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• What objects would get defined in a Bridge scoring app (Javascript)

  - by Alex Mcp

  I'm writing a Bridge (card game) scoring application as practice in javascript, and am looking for suggestions on how to set up my objects. I'm pretty new to OO in general, and would love a survey of how and why people would structure a program to do this (the "survey" begets the CW mark. Additionally, I'll happily close this if it's out of range of typical SO discussion). The platform is going to be a web-app for webkit on the iPhone, so local storage is an option. My basic structure is like this: var Team = { player1: , player2: , vulnerable: , //this is a flag for whether or //not you've lost a game yet, affects scoring scoreAboveLine: , scoreBelowLine: gamesWon: }; var Game = { init: ,//function to get old scores and teams from DB currentBid: , score: , //function to accept whether bid was made and apply to Teams{} save: //auto-run that is called after each game to commit to DB }; So basically I'll instantiate two teams, and then run loops of game.currentBid() and game.score. Functionally the scoring is working fine, but I'm wondering if this is how someone else would choose to break down the scoring of Bridge, and if there are any oversights I've made with regards to OO-ness and how I've abstracted the game. Thanks!

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• Load Images in WPF application

  - by LLS

  I am not familiar with WPF, and I just feel quite confusing. I am trying to create a little computer game, and there are elements I want to display dynamically. I use Image class and add the images to a canvas. But I'm not sure whether it's a good practice. I feel that adding controls to canvas seem to be a little wired. And I'm a little concerned about the performance, because I may need many images. The real problem is, I can't load the images from the image files. I see an example in a text book like this (XMAL): <Image Panel.ZIndex="0" Margin="0,0,0,0" Name ="image1"> <Image.Source> <BitmapImage UriSource="Bell.gif" /> </Image.Source> </Image> Where Bell.gif is added into the project. And I tried to copy this in code to create an image. new Image { Source = new BitmapImage(new Uri("Blockade.bmp"))} But I got invalid Uri exception. After some search in the Internet, I found that loading resources dynamically seems to be difficult. Can I load the files added to the project dynamically? If I use absolute path then it's OK. But I can't expect every computer will put the files in the same location. Can I use relative path? I tried new Image { Source = new BitmapImage(new Uri(@"Pictures\Blank Land.bmp", UriKind.Relative)) } But it doesn't work. (The image is blank) Thanks.

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• C# - Removing event handlers - FormClosing event or Dispose() method

  - by Andy

  Suppose I have a form opened via the .ShowDialog() method. At some point I attach some event handlers to some controls on the form. e.g. // Attach radio button event handlers. this.rbLevel1.Click += new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel2.Click += new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel3.Click += new EventHandler(this.RadioButton_CheckedChanged); When the form closes, I need to remove these handlers, right? At present, I am doing this when the FormClosing event is fired. e.g. private void Foo_FormClosing(object sender, FormClosingEventArgs e) { // Detach radio button event handlers. this.rbLevel1.Click -= new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel2.Click -= new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel3.Click -= new EventHandler(this.RadioButton_CheckedChanged); } However, I have seen some examples where handlers are removed in the Dispose() method. Is there a 'best-practice' way of doing this? (Using C#, Winforms, .NET 2.0) Thanks.

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• How does a java web project architecture look like without EJB3 ?

  - by Hendrik

  A friend and I are building a fairly complex website based on java. (PHP would have been more obvious but we chose for java because the educational aspect of this project is important to us) We have already decided to use JSF (with richfaces) for the front end and JPA for the backend and so far we have decided not to use EJB3 for the business layer. The reason we've decided not to use EJB3 is because - and please correct me if I am wrong - if we use EJB3 we can only run it on a full blown java application server like jboss and if we don't use EJB3 we can still run it on a lightweight server like tomcat. We want to keep speed and cost of our future web server in mind. So far i've worked on two JEE projects and both used the full stack with web business logic factories/persistence service entities with every layer a seperate module. Now here is my question, if you dont use EJB3 in the business logic layer. What does the layer look like? Please tell what is common practice when developing java web projects without ejb3? Do you think business logic layer can be thrown out altogether and have business logic in the backing beans? If you keep the layer, do you have all business methods static? Or do you initialize each business class as needed in the backing beans in every session as needed?

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• use of assertions for type checking in php?

  - by user151841

  I do some checking of arguments in my classes in php using exception-throwing functions. I have functions that do a basic check ( ===, in_array etc ) and throw an exception on false. So I can do assertNumeric($argument, "\$argument is not numeric."); instead of if ( ! is_numeric($argument) ) { throw new Exception("\$argument is not numeric."); } Saves some typing I was reading in the comments of the php manual page on assert() that As noted on Wikipedia - "assertions are primarily a development tool, they are often disabled when a program is released to the public." and "Assertions should be used to document logically impossible situations and discover programming errors— if the 'impossible' occurs, then something fundamental is clearly wrong. This is distinct from error handling: most error conditions are possible, although some may be extremely unlikely to occur in practice. Using assertions as a general-purpose error handling mechanism is usually unwise: assertions do not allow for graceful recovery from errors, and an assertion failure will often halt the program's execution abruptly. Assertions also do not display a user-friendly error message." This means that the advice given by "gk at proliberty dot com" to force assertions to be enabled, even when they have been disabled manually, goes against best practices of only using them as a development tool So, am I 'doing it wrong'? What other/better ways of doing this are there?

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• Explaining to boss why we need to avoid horizontal scroll

  - by Bradley Herman

  I need help explaining to my boss why her design is poor on a clients website. She has no knowledge of web and it can be difficult as a web developer working with a woman who is a graphic designer (not even a web designer really). On a current site she has designed, an image bar "needs" to be like 1200px according to her, though it isn't necessary with the content. I'll show a quick sketch to illustrate what's going on: http://imgur.com/MNGOT.jpg As you see, the banner spills out past the 960px of the content and as wide as 1200px. This creates a horizontal scroll when all the content is viewable within the 960px wide viewport. I need to make this an img and not a css background because it's a jquery slideshow that fades from image to image. I think this is a big problem because a lot of people are going to get a horizontal scroll bar imposed in their browser when they're still able to see all the relevant content. How do I help her explain it. She thinks no one will notice and it'll be fine, I think it's very bad practice and confusing to the end user. Any help?

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• Is it valid to use unsafe struct * as an opaque type instead of IntPtr in .NET Platform Invoke?

  - by David Jeske

  .NET Platform Invoke advocates declaring pointer types as IntPtr. For example, the following [DllImport("user32.dll")] static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, Int32 wParam, Int32 lParam); However, I find when interfacing with interesting native interfaces, that have many pointer types, flattening everything into IntPtr makes the code very hard to read and removes the typical typechecking that a compiler can do. I've been using a pattern where I declare an unsafe struct to be an opaque pointer type. I can store this pointer type in a managed object, and the compiler can typecheck it form me. For example: class Foo { unsafe struct FOO {}; // opaque type unsafe FOO *my_foo; class if { [DllImport("mydll")] extern static unsafe FOO* get_foo(); [DllImport("mydll")] extern static unsafe void do_something_foo(FOO *foo); } public unsafe Foo() { this.my_foo = if.get_foo(); } public unsafe do_something_foo() { if.do_something_foo(this.my_foo); } While this example may not seem different than using IntPtr, when there are several pointer types moving between managed and native code, using these opaque pointer types for typechecking is a godsend. I have not run into any trouble using this technique in practice. However, I also have not seen an examples of anyone using this technique, and I wonder why. Is there any reason that the above code is invalid in the eyes of the .NET runtime? My main question is about how the .NET GC system treats "unsafe FOO *my_foo". Is this pointer something the GC system is going to try to trace, or is it simply going to ignore it? My hope is that because the underlying type is a struct, and it's declared unsafe, that the GC would ignore it. However, I don't know for sure. Thoughts?

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• moving audio over a local network using GStreamer

  - by James Turner

  I need to move realtime audio between two Linux machines, which are both running custom software (of mine) which builds on top of Gstreamer. (The software already has other communication between the machines, over a separate TCP-based protocol - I mention this in case having reliable out-of-band data makes a difference to the solution). The audio input will be a microphone / line-in on the sending machine, and normal audio output as the sink on the destination; alsasrc and alsasink are the most likely, though for testing I have been using the audiotestsrc instead of a real microphone. GStreamer offers a multitude of ways to move data round over networks - RTP, RTSP, GDP payloading, UDP and TCP servers, clients and sockets, and so on. There's also many examples on the web of streaming both audio and video - but none of them seem to work for me, in practice; either the destination pipeline fails to negotiate caps, or I hear a single packet and then the pipeline stalls, or the destination pipeline bails out immediately with no data available. In all cases, I'm testing on the command-line just gst-launch. No compression of the audio data is required - raw audio, or trivial WAV, uLaw or aLaw encoding is fine; what's more important is low-ish latency.

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• MS Surface Tag Visualizer steals contact events

  - by Isak Savo

  I'm struggling with the TagVisualizer control on an MS Surface project. In theory the control seems great, allowing you to respond to input from real world physical objects The problem is that the control will cover the entire screen (since I want to capture tags on the entire screen) and as such, no other controls in my app will receive the touch events. (Unless, they are direct ascendants in the visual tree). In my app, I want to have a "layer" type of a approach, where each layer can respond to (contact) input: Window `- Grid `- LayersPanel `- TagVisualizer `- Layer 1 `- Layer 2 `- Layer 3 `- Layer 4 Now it doesn't matter where I put the tag visualizer, it's always going to steal contact events from all or some of the other layers. (due to the nature of RoutedEvents) To me, it seems like the control is completely useless in practice as it will always interfere with your application's other controls. What am I missing here? So my questions are: Any suggestions on how to work around this? Has anyone used TagVisualizers in a similar scenario? If so, how did you solve this? By the way, the layers all work fine, since they will only steal events that are directly on top of their sub elements (the rest of the layer is invisible to hit testing)

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