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  • Programming style question on how to code functions

    - by shawnjan
    Hey all! So, I was just coding a bit today, and I realized that I don't have much consistency when it comes to a coding style when programming functions. One of my main concerns is whether or not its proper to code it so that you check that the input of the user is valid OUTSIDE of the function, or just throw the values passed by the user into the function and check if the values are valid in there. Let me sketch an example: I have a function that lists hosts based on an environment, and I want to be able to split the environment into chunks of hosts. So an example of the usage is this: listhosts -e testenv -s 2 1 This will get all the hosts from the "testenv", split it up into two parts, and it is displaying part one. In my code, I have a function that you pass it in a list, and it returns a list of lists based on you parameters for splitting. BUT, before I pass it a list, I first verify the parameters in my MAIN during the getops process, so in the main I check to make sure there are no negatives passed by the user, I make sure the user didnt request to split into say, 4 parts, but asking to display part 5 (which would not be valid), etc. tl;dr: Would you check the validity of a users input the flow of you're MAIN class, or would you do a check in your function itself, and either return a valid response in the case of valid input, or return NULL in the case of invalid input? Obviously both methods work, I'm just interested to hear from experts as to which approach is better :) Thanks for any comments and suggestions you guys have!

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  • MVC2 DataAnnotations on ViewModel - Don't understand using it with MVVM pattern

    - by ScottSEA
    I have an MVC2 Application that uses MVVM pattern. I am trying use Data Annotations to validate form input. In my ThingsController I have two methods: [HttpGet] public ActionResult Index() { return View(); } public ActionResult Details(ThingsViewModel tvm) { if (!ModelState.IsValid) return View(tvm); try { Query q = new Query(tvm.Query); ThingRepository repository = new ThingRepository(q); tvm.Things = repository.All(); return View(tvm); } catch (Exception) { return View(); } } My Details.aspx view is strongly typed to the ThingsViewModel: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Config.Web.Models.ThingsViewModel>" %> The ViewModel is a class consisting of a IList of returned Thing objects and the Query string (which is submitted on the form) and has the Required data annotation: public class ThingsViewModel { public IList<Thing> Things{ get; set; } [Required(ErrorMessage="You must enter a query")] public string Query { get; set; } } When I run this, and click the submit button on the form without entering a value I get a YSOD with the following error: The model item passed into the dictionary is of type 'Config.Web.Models.ThingsViewModel', but this dictionary requires a model item of type System.Collections.Generic.IEnumerable`1[Config.Domain.Entities.Thing]'. How can I get Data Annotations to work with a ViewModel? I cannot see what I'm missing or where I'm going wrong - the VM was working just fine before I started mucking around with validation.

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  • How to append a row to a TableViewSection in Titanium?

    - by Mike Trpcic
    I'm developing an iPhone application in Titanium, and need to append a row to a particular TableViewSection. I can't do this on page load, as it's done dynamically by the user throughout the lifecycle of the application. The documentation says that the TableViewSection has an add method which takes two arguments, but I can't make it work. Here's my existing code: for(var i = 0; i <= product_count; i++){ productsTableViewSection.add( Ti.UI.createTableViewRow({ title:'Testing...' }) ); } That is just passing one argument in, and that causes Titanium to die with an uncaught exception: 2010-04-26 16:57:18.056 MyApplication[72765:207] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 2. The number of rows contained in an existing section after the update (2) must be equal to the number of rows contained in that section before the update (1), plus or minus the number of rows inserted or deleted from that section (0 inserted, 0 deleted).' 2010-04-26 16:57:18.056 MyApplication[72765:207] Stack: ( The exception looks like it did add the row, but it's not allowed to for some reason. Since the documentation says that TableViewSection takes in "view" and "row", I tried the following: for(var i = 0; i <= product_count; i++){ productsTableViewSection.add( Ti.UI.createView({}), Ti.UI.createTableViewRow({ title:'Testing...' }) ); } The above code doesn't throw the exception, but it gives a [WARN]: [WARN] Invalid type passed to function. expected: TiUIViewProxy, was: TiUITableViewRowProxy in -[TiUITableViewSectionProxy add:] (TiUITableViewSectionProxy.m:62) TableViewSections don't seem to support any methods like appendRow, or insertRow, so I don't know where else to go with this. I've looked through the KitchenSink app, but there are no examples that I could find of adding a row to a TableViewSection. Any help is appreciated.

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  • OOP - Handling Automated Instances of a Class - PHP

    - by dscher
    This is a topic that, as a beginner to PHP and programming, sort of perplexes me. I'm building a stockmarket website and want users to add their own stocks. I can clearly see the benefit of having each stock be a class instance with all the methods of a class. What I am stumped on is the best way to give that instance a name when I instantiate it. If I have: class Stock() { ....doing stuff..... } what is the best way to give my instances of it a name. Obviously I can write: $newStock = new Stock(); $newStock.getPrice(); or whatever, but if a user adds a stock via the app, where can the name of that instance come from? I guess that there is little harm in always creating a new child with $newStock = new Stock() and then storing that to the DB which leads me to my next question! What would be the best way to retrieve 20 user stocks(for example) into instances of class Stock()? Do I need to instantiate 20 new instances of class Stock() every time the user logs in or is there something I'm missing? I hope someone answers this and more important hope a bunch of people answer this and it somehow helps someone else who is having a hard time wrapping their head around what probably leads to a really elegant solution. Thanks guys!

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  • Persistant Http client connections in java

    - by Akusete
    I am trying to write a simple Http client application in Java and am a bit confused by the seemingly different ways to establish Http client connections, and efficiently re-use the objects. Current I am using the following steps (I have left out exception handling for simplicity) Iterator<URI> uriIterator = someURIs(); HttpClient client = new DefaultHttpClient(); while (uriIterator.hasNext()) { URI uri = uriIterator.next(); HttpGet request = new HttpGet(uri); HttpResponse response = client.execute(request); HttpEntity entity = response.getEntity(); InputStream s = entity.getContent(); processStream (); s.close(); } In regard to the code above, my questions is: Assuming all URI's are pointing to the same host (but different resources on that host). What is the recommended way to use a single http connection for all requests? And how do you close the connection after the last request? --edit: Also what is the difference between using uri.openConnection(), versus HttpClient? Which is preferable, and what other methods exist?

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  • converting a timestring to a duration

    - by radman
    Hi, At the moment I am trying to read in a timestring formatted and create a duration from that. I am currently trying to use the boost date_time time_duration class to read and store the value. boost date_time provides a method time_duration duration_from_string(std::string) that allows a time_duration to be created from a time string and it accepts strings formatted appropriately ("[-]h[h][:mm][:ss][.fff]".). Now this method works fine if you use a correctly formatted time string. However if you submit something invalid like "ham_sandwich" or "100" then you will still be returned a time_duration that is not valid. Specifically if you try to pass it to a standard output stream then an assertion will occur. My question is: Does anyone know how to test the validity of the boost time_duration? and failing that can you suggest another method of reading a timestring and getting a duration from it? Note: I have tried the obvious testing methods that time_duration provides; is_not_a_date_time(), is_special() etc and they don't pick up that there is an issue. Using boost 1.38.0

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  • Passing arguments and values from HTML to jQuery (events)

    - by Jaroslav Moravec
    What is the practice to pass arguments from HTML to jQuery events function. For example getting id of row from db: <tr class="jq_killMe" id="thisItemId-id"> ... </tr> and jQuery: $(".jq_killMe").click(function () { var tmp = $(this).attr('id).split("-"); var id = tmp[0] // ... } What's the best practise, if I want to pass more than one argument? Is it better not to use jQuery? For example: <tr onclick="killMe('id')"> ... </tr> I didn't find the answer on my question, I will be glad even for links. Thanks. Edit (pre solution) So you suggested two methods to do that: Add custom attributes to element (XHTML) Use attribute ID and parse it by regex Attribute data-* attributes in HTML5 Use hidden children elements I like first solution, but... I would like to (I have to (employer)) produce valid code. Here is a nice question and answers: http://stackoverflow.com/questions/994856/so-what-if-custom-html-attributes-arent-valid-xhtml And the second is not so pretty as the first, but valid. So the compromise is... The third is the solution for future, but here is a lot of CMS where we have to use XHTML or HTML4. (And HTML5 is the long process)

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  • Recommend me an architecture for this Facebook application

    - by andybaird
    Firstly, this question is subjective. There is not a right answer for this question and it really depends on what works for you. I'm hoping to use this thread as a breeding ground for ideas. I hope this is acceptable in this medium. I'm working on building a Facebook app that will be replacing an already popular app that gets ~50k hits a day. The original app is using a very typical LAMP setup with help from some Zend libraries for database layer extraction. For the most part the app worked well, except to solve a lot of issues I ended up fragmenting tables to speed things up. As a result, I couldn't do a lot of things with the app that I wanted to (namely any processing using aggregate data that needed to be returned quickly) So I'm starting to design plans for the next version of this application, and I have a whole bunch of new and cool features that I know would choke my current setup. I'm looking for technological recommendations of data storage methods that scale well. The database does not necessarily need to be relational, simple key/value storage would suffice (although at present time I know little to nothing about KV stores) What's your recommendation? How would you tackle this? I'd like to take a completely free approach to this -- although I am most familiar and comfortable using PHP, I want to leave all technical options open.

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  • Issue calling superclass method in subclass constructor

    - by stormin986
    I get a NullPointerException calling a Superclass Method in Subclass Inner Class Constructor... What's the Deal? In my application's main class (subclass of Application), I have a public inner class that simply contains 3 public string objects. In the parent class I declare an object of that inner class. public class MainApplication extends Application { public class Data { public String x; public String y; public String z; } private Data data; MainApplication() { data = new Data() data.x = SuperClassMethod(); } } After I instantiate the object in the constructor, I get a runtime error when I try to assign a value in the inner class with a superclass method. Any idea what's up here?? Can you not call superclass methods in the subclass constructor? ** Edit ** Original question was about inner class member assignment in outer class constructor. Turned out the issue was with calling a superclass method in the class's constructor. It was giving me a null pointer exception. Thus, the question has changed.

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  • Java KeyListener in separate class

    - by Chris
    So I have my main class here, where basically creates a new jframe and adds a world object to it. The world object is basically where all drawing and keylistening would take place... public class Blobs extends JFrame{ public Blobs() { super("Blobs :) - By Chris Tanaka"); setVisible(true); setResizable(false); setSize(1000, 1000); setIgnoreRepaint(true); setDefaultCloseOperation(EXIT_ON_CLOSE); add(new World()); } public static void main(String[] args) { new Blobs(); } } How exactly would you get key input from the world class? (So far I have my world class extending a jpanel and implementing a keylistener. In the constructor i addKeyListener(this). I also have these methods since they are auto implemented: public void keyPressed(KeyEvent e) { if (e.getKeyCode() == KeyEvent.VK_W) System.out.println("Hi"); } public void keyReleased(KeyEvent e) {} public void keyTyped(KeyEvent e) {} However this does not seem to work?

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  • Case class copy() method abstraction.

    - by Joa Ebert
    I would like to know if it is possible to abstract the copy method of case classes. Basically I have something like sealed trait Op and then something like case class Push(value: Int) extends Op and case class Pop() extends Op. The first problem: A case class without arguments/members does not define a copy method. You can try this in the REPL. scala> case class Foo() defined class Foo scala> Foo().copy() <console>:8: error: value copy is not a member of Foo Foo().copy() ^ scala> case class Foo(x: Int) defined class Foo scala> Foo(0).copy() res1: Foo = Foo(0) Is there a reason why the compiler makes this exception? I think it is rather unituitive and I would expect every case class to define a copy method. The second problem: I have a method def ops: List[Op] and I would like to copy all ops like ops map { _.copy() }. How would I define the copy method in the Op trait? I get a "too many arguments" error if I say def copy(): this.type. However, since all copy() methods have only optional arguments: why is this incorrect? And, how do I do that correct? By making another method named def clone(): this.type and write everywhere def clone() = copy() for all the case classes? I hope not.

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  • @PrePersist with entity inheritance

    - by gerry
    I'm having some problems with inheritance and the @PrePersist annotation. My source code looks like the following: _the 'base' class with the annotated updateDates() method: @javax.persistence.Entity @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) public class Base implements Serializable{ ... @Id @GeneratedValue protected Long id; ... @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date creationDate; @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date lastModificationDate; ... public Date getCreationDate() { return creationDate; } public void setCreationDate(Date creationDate) { this.creationDate = creationDate; } public Date getLastModificationDate() { return lastModificationDate; } public void setLastModificationDate(Date lastModificationDate) { this.lastModificationDate = lastModificationDate; } ... @PrePersist protected void updateDates() { if (creationDate == null) { creationDate = new Date(); } lastModificationDate = new Date(); } } _ now the 'Child' class that should inherit all methods "and annotations" from the base class: @javax.persistence.Entity @NamedQueries({ @NamedQuery(name=Sensor.QUERY_FIND_ALL, query="SELECT s FROM Sensor s") }) public class Sensor extends Entity { ... // additional attributes @Column(nullable=false) protected String value; ... // additional getters, setters ... } If I store/persist instances of the Base class to the database, everything works fine. The dates are getting updated. But now, if I want to persist a child instance, the database throws the following exception: MySQLIntegrityConstraintViolationException: Column 'CREATIONDATE' cannot be null So, in my opinion, this is caused because in Child the method "@PrePersist protected void updateDates()" is not called/invoked before persisting the instances to the database. What is wrong with my code?

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  • How to build a Django form which requires a delay to be re-submitted ?

    - by pierre-guillaume-degans
    Hey, In order to avoid spamming, I would like to add a waiting time to re-submit a form (i.e. the user should wait a few seconds to submit the form, except the first time that this form is submitted). To do that, I added a timestamp to my form (and a security_hash field containing the timestamp plus the settings.SECRET_KEY which ensures that the timestamp is not fiddled with). This look like: class MyForm(forms.Form): timestamp = forms.IntegerField(widget=forms.HiddenInput) security_hash = forms.CharField(min_length=40, max_length=40, widget=forms.HiddenInput) # + some other fields.. # + methods to build the hash and to clean the timestamp... # (it is based on django.contrib.comments.forms.CommentSecurityForm) def clean_timestamp(self): """Make sure the delay is over (5 seconds).""" ts = self.cleaned_data["timestamp"] if not time.time() - ts > 5: raise forms.ValidationError("Timestamp check failed") return ts # etc... This works fine. However there is still an issue: the timestamp is checked the first time the form is submitted by the user, and I need to avoid this. Any idea to fix it ? Thank you ! :-)

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  • What are Code Smells? What is the best way to correct them?

    - by Rob Cooper
    OK, so I know what a code smell is, and the Wikipedia Article is pretty clear in its definition: In computer programming, code smell is any symptom in the source code of a computer program that indicates something may be wrong. It generally indicates that the code should be refactored or the overall design should be reexamined. The term appears to have been coined by Kent Beck on WardsWiki. Usage of the term increased after it was featured in Refactoring. Improving the Design of Existing Code. I know it also provides a list of common code smells. But I thought it would be great if we could get clear list of not only what code smells there are, but also how to correct them. Some Rules Now, this is going to be a little subjective in that there are differences to languages, programming style etc. So lets lay down some ground rules: ** ONE SMELL PER ANSWER PLEASE! & ADVISE ON HOW TO CORRECT! ** See this answer for a good display of what this thread should be! DO NOT downmod if a smell doesn't apply to your language or development methodology We are all different. DO NOT just quickly smash in as many as you can think of Think about the smells you want to list and get a good idea down on how to work around. DO downmod answers that just look rushed For example "dupe code - remove dupe code". Let's makes it useful (e.g. Duplicate Code - Refactor into separate methods or even classes, use these links for help on these common.. etc. etc.). DO upmod answers that you would add yourself If you wish to expand, then answer with your thoughts linking to the original answer (if it's detailed) or comment if its a minor point. DO format your answers! Help others to be able to read it, use code snippets, headings and markup to make key points stand out!

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  • Cast object to interface when created via reflection

    - by Al
    I'm trying some stuff out in Android and I'm stuck at when trying to cast a class in another .apk to my interface. I have the interface and various classes in other .apks that implement that interface. I find the other classes using PackageManager's query methods and use Application#createPackageContext() to get the classloader for that context. I then load the class, create a new instance and try to cast it to my interface, which I know it definitely implements. When I try to cast, it throws a class cast exception. I tried various things like loading the interface first, using Class#asSubclass, etc, none of which work. Class#getInterfaces() shows the interface is implemented. My code is below: PackageManager pm = getPackageManager(); List<ResolveInfo> lr = pm.queryIntentServices(new Intent("com.example.some.action"), 0); ArrayList<MyInterface> list = new ArrayList<MyInterface>(); for (ResolveInfo r : lr) { try { Context c = getApplication().createPackageContext(r.serviceInfo.packageName, Context.CONTEXT_IGNORE_SECURITY | Context.CONTEXT_INCLUDE_CODE); ClassLoader cl = c.getClassLoader(); String className = r.serviceInfo.name; if (className != null) { try { Class<?> cls = cl.loadClass(className); Object o = cls.newInstance(); if (o instanceof MyInterface) { //fails list.add((MyInterface) o); } } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } // some exceptions removed for readability } } catch (NameNotFoundException e1) { e1.printStackTrace(); }

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  • [JAX-B] How can I ignore a superclass?

    - by MrSpandex
    I'm trying to write a web service for the java.util.logging api. So I wrote a class MyLogRecord that inherits from LogRecord. I annotated this class with JAX-B annotations, including @XmlAccessorType(XmlAccessType.NONE) so it would ignore non-annotated fields and properties. When I start up tomcat, I get errors that java.util.logging.Level and other java.util.logging classes do not have a default constructor, but none of my annotated methods make any reference to the Level class or any of the other java.util.logging classes. These are referenced by the parent class. My sub-class has everything it needs defined. How can I get JAX-B to ignore the parent class completely? Update: I found another post on this, which suggests modifying the parent class. This is obviously not possible because I am extending a java.util class. IS there any way to do this without modifying the superclass? Update2: I found a thread on java.net for a similar problem. That thread resulted in an enhancement request, which was marked as a duplicate of another issue, which resulted in the @XmlTransient annotation. The comments on these bug reports lead me to believe this is impossible in the current spec.

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  • C++ Problems with #import of .NET out-of-proc server.

    - by jm
    In C++ program, I am trying to #import TLB of .NET out of proc server. I get errors like: z:\server.tlh(111) : error C2146: syntax error : missing ';' before identifier 'GetType' z:\server.tlh(111) : error C2501: 'TypePtr' : missing storage-class or type specifiers z:\server.tli(74) : error C2143: syntax error : missing ';' before 'tag::id' z:\server.tli(74) : error C2433: 'TypePtr' : 'inline' not permitted on data declarations z:\server.tli(74) : error C2501: '_TypePtr' : missing storage-class or type specifiers z:\server.tli(74) : fatal error C1004: unexpected end of file found The TLH looks like: ... _bstr_t GetToString ( ); VARIANT_BOOL Equals ( const _variant_t & obj ); long GetHashCode ( ); _TypePtr GetType ( ); long Open ( ); ... I am not really interested in the having the base object .NET object methods like GetType(), Equals(), etc. But GetType() seems to be causing problems. Some google research indicates I could #import MSCORLIB.TLB (or put it in path), but I can't get that to compile either. Any tips?

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  • Custom control doesn't fire validation

    - by Ed Woodcock
    I've written a custom ASP.net control that descends from LinkButton and overrides the Render() method. I'm using it to replace ImageButtons in the site I'm working on so we don't have to have an image for each button. This control works fine, does the required post-backs etc., however it doesn't fire the validators in its validation group. This is obviously an issue. The code for the control is (condensed) as follows: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public class CustomButton : LinkButton { public string SpanCssClass { get; set; } protected override void Render(HtmlTextWriter writer) { if (!Visible) { return; } writer.AddAttribute(HtmlTextWriterAttribute.Name, UniqueID); writer.AddAttribute(HtmlTextWriterAttribute.Id, ClientID); writer.AddAttribute(HtmlTextWriterAttribute.Class, CssClass); string postback = string.IsNullOrEmpty(OnClientClick) ? "javascript:__doPostBack('" + UniqueID + "','');" : OnClientClick; writer.AddAttribute(HtmlTextWriterAttribute.Href, postback); writer.RenderBeginTag(HtmlTextWriterTag.A); writer.AddAttribute(HtmlTextWriterAttribute.Class, SpanCssClass); writer.RenderBeginTag(HtmlTextWriterTag.Span); writer.Write(Text); writer.RenderEndTag(); writer.RenderEndTag(); } } Does anyone know why this would not be causing the validators to fire? I was under the impression that leaving all the other methods in LinkButton un-overridden would leave all the other functionality the same!

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  • How do I implement a listener pattern over RMI using Spring?

    - by predhme
    So here is a generalized version of our application desgin: @Controller public class MyController { @Autowired private MyServiceInterface myServiceInterface; @RequestMapping("/myURL") public @ResponseBody String doSomething() { MyListenerInterface listener = new MyListenerInterfaceImpl(); myServiceInterface.doThenCallListener(listener); // do post stuff } } public interface MyListenerInterface { public void callA(); public void callB(); } public class MyListenerInterfaceImpl implements MyListenerInterface { // ... omitted for clarity } public interface MyServiceInterface { public void doThenCallListener(MyListenerInterface listener); } public class MyServiceImpl { public void doThenCallListener(MyListenerInterface listener) { // do stuff listener.callA(); } } Basically I have a controller that is being called via AJAX in which I am looking to return a response as a string. However, I need to make a call to the backend (MyServiceInterface). That guy is exposed through RMI by using Spring (man that was easy). But the service method as described requires a listener to be registered for invokation completion purposes. So what I assume I need to achieve is transparently to the backend make it so that when the listener methods are called, really the call is going over RMI. I would have thought Spring would have a simple way to wrap a POJO (not a service singleton) with RMI calls. I looked through their documentation but they had nothing besides exposing services via RMI. Could someone point me in the right direction?

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  • Moving UIScrollView in App

    - by jsetting32
    Currently, I am attempting to create the same effect as Yahoo! Weather's App where the vital day information is at the bottom of the page on the top of a UIScrollView, that's contained by a UIView. I am having a hard time thinking about how this is going to happen or how I should implement this. If the user taps on the top of the UIScrollView which is located near the bottom of the laoded UIView, and starts to scroll up (/), the UIScrollView's frame should be moved to the TOP of the current UIView's frame. So the UIScrollView's y-value should change to UIView's (self.view.frame.origin.y) if the user starts scrolling UP on the UIScrollView which is located on the UIView's y-pixel ~280. Here's what the UIViewController should look like in the beginning of loading the ViewController... Then once the user slides his finger from the bottom to the top of the screen... this should happen........ And when the user scrolls to the top of the UIScrollView with all the content within it... the view should go back to the start picture shown... How is this done? I was thinking several UIGestureRecognizer's and Instantiating the UIscrollview at the lower part of the UIView... _weatherView = [[UIScrollView alloc] initWithFrame:CGRectMake(self.view.frame.origin.x, self.view.frame.origin.y + 250, self.view.bounds.size.width, self.view.bounds.size.height - 44)]; _weatherView.contentSize = CGSizeMake(self.view.bounds.size.width, self.view.bounds.size.height * 4); _weatherView.backgroundColor = [UIColor clearColor]; [self.view addSubview:_weatherView]; The adding some UIGestureRecognizer delegate method.... But anyone have any ideas on the UIGestureRecognizer delegate method? And how it should be implemented? I can write the psuedo-code but I am having problems finding the delegate methods :P Thank you!!! ---- Break Time.... :)

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  • How to retrieve view of MultiIndex DataFrame

    - by Henry S. Harrison
    This question was inspired by this question. I had the same problem, updating a MultiIndex DataFrame by selection. The drop_level=False solution in Pandas 0.13 will allow me to achieve the same result, but I am still wondering why I cannot get a view from the MultiIndex DataFrame. In other words, why does this not work?: >>> sat = d.xs('sat', level='day', copy=False) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 2248, in xs raise ValueError('Cannot retrieve view (copy=False)') ValueError: Cannot retrieve view (copy=False) Of course it could be only because it is not implemented, but is there a reason? Is it somehow ambiguous or impossible to implement? Returning a view is more intuitive to me than returning a copy then later updating the original. I looked through the source and it seems this situation is checked explicitly to raise an error. Alternatively, is it possible to get the same sort of view from any of the other indexing methods? I've experimented but have not been successful. [edit] Some potential implementations are discussed here. I guess with the last question above I'm wondering what the current best solution is to index into arbitrary multiindex slices and cross-sections.

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  • How to convert Unicode strings (\u00e2, etc) into NSString for display?

    - by karlbecker_com
    I am trying to support arbitrary unicode from a variety of international users. They have already put a bunch of data into sqlite databases on their iPhones, and now I want to capture the data into a database, then send it back to their device. Right now I am using a php page that is sending data back to from an internet mysql database. The data is saved in the mysql database properly, but when it's sent back it comes out as unicode text, such as Frank\u00e2\u0080\u0099s iPad instead of just Frank's iPad where the apostrophe should really be a curly apostrophe. The answer posted to another question indicates that there is no built-in Cocoa methods to convert the "\u00e2\u0080\u0099" portion of the unicode string from the webserver to an NSString object. Is this correct? That seems really surprising (and scarily disappointing), since Cocoa definitely allows input from many different Unicode characters, and I need to support any arbitrary language that I have never heard of, and all of the possible characters. I save them to and from the local sqlite database just fine now, but once I send it to a web server, then perhaps pull down different data, I want to ensure the data pulled from the web server is correctly formatted.

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  • Are there pitfalls to using static class/event as an application message bus

    - by Doug Clutter
    I have a static generic class that helps me move events around with very little overhead: public static class MessageBus<T> where T : EventArgs { public static event EventHandler<T> MessageReceived; public static void SendMessage(object sender, T message) { if (MessageReceived != null) MessageReceived(sender, message); } } To create a system-wide message bus, I simply need to define an EventArgs class to pass around any arbitrary bits of information: class MyEventArgs : EventArgs { public string Message { get; set; } } Anywhere I'm interested in this event, I just wire up a handler: MessageBus<MyEventArgs>.MessageReceived += (s,e) => DoSomething(); Likewise, triggering the event is just as easy: MessageBus<MyEventArgs>.SendMessage(this, new MyEventArgs() {Message="hi mom"}); Using MessageBus and a custom EventArgs class lets me have an application wide message sink for a specific type of message. This comes in handy when you have several forms that, for example, display customer information and maybe a couple forms that update that information. None of the forms know about each other and none of them need to be wired to a static "super class". I have a couple questions: fxCop complains about using static methods with generics, but this is exactly what I'm after here. I want there to be exactly one MessageBus for each type of message handled. Using a static with a generic saves me from writing all the code that would maintain the list of MessageBus objects. Are the listening objects being kept "alive" via the MessageReceived event? For instance, perhaps I have this code in a Form.Load event: MessageBus<CustomerChangedEventArgs>.MessageReceived += (s,e) => DoReload(); When the Form is Closed, is the Form being retained in memory because MessageReceived has a reference to its DoReload method? Should I be removing the reference when the form closes: MessageBus<CustomerChangedEventArgs>.MessageReceived -= (s,e) => DoReload();

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  • How does static code run with multiple threads?

    - by Krisc
    I was reading http://stackoverflow.com/questions/1511798/threading-from-within-a-class-with-static-and-non-static-methods and I am in a similar situation. I have a static method that pulls data from a resource and creates some runtime objects based on the data. static class Worker{ public static MyObject DoWork(string filename){ MyObject mo = new MyObject(); // ... does some work return mo; } } The method takes awhile (in this case it is reading 5-10mb files) and returns an object. I want to take this method and use it in a multiple thread situation so I can read multiple files at once. Design issues / guidelines aside, how would multiple threads access this code? Let's say I have something like this... class ThreadedWorker { public void Run() { Thread t = new Thread(OnRun); t.Start(); } void OnRun() { MyObject mo = Worker.DoWork("somefilename"); mo.WriteToConsole(); } } Does the static method run for each thread, allowing for parallel execution?

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  • Is NSManagedObjectContext autosaved or am I looking at NSFetchedResultsController's cache?

    - by Andreas
    I'm developing an iPhone app where I use a NSFetchedResultsController in the main table view controller. I create it like this in the viewDidload of the main table view controller: NSSortDescriptor *sortDescriptorDate = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES]; NSSortDescriptor *sortDescriptorTime = [[NSSortDescriptor alloc] initWithKey:@"start" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptorDate,sortDescriptorTime, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; [sortDescriptorDate release]; [sortDescriptorTime release]; [sortDescriptors release]; controller = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:context sectionNameKeyPath:@"date" cacheName:nil]; [fetchRequest release]; NSError *error; BOOL success = [controller performFetch:&error]; Then, in a subsequent view, I create a new object on the context: TestObject *testObject = [NSEntityDescription insertNewObjectForEntityForName:@"TestObject" inManagedObjectContext:context]; The TestObject has several related object which I create in the same way and add to the testObject using the provided add...Objects methods. Then, if before saving the context, I press cancel and go back to the main table view, nothing is shown as expected. However, if I restart the app, the object I created on the context shows in the main table view. How come? At first, I thought it was because the NSFetchedResultsController was reading from the cache, but as you can see I set this to nil just to test. Also, [context hasChanges] returns true after I restart. What am I missing here?

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