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  • Passing control references as ref parameters

    - by Enmanuel
    Hi everyone. Please help me out here because im getting kind of confused.. I have a form in a C# winforms project and a couple of methods that are suposed to perform some tasks for this particular form and all derived ones, so one of those helper methods can make the example.. this one should fill comboboxes with a dataset. Its working properly now but when i coded the method with this signature protected void FillComboBox(kComboBox target, IEntClass_DA entity) { target.DataSource = entity.GetList().Tables[0]; target.DisplayMember = "name"; target.ValueMember = "id"; } I saw that the displayMember and ValueMember in the comboboxes were not holding the values after the method call. I just thought I should use ref parameters so the asignments are not wasted in read-only reference variables. It was ok by then but later, making an exercise of passing the whole form as a parameter I was warned by the compiler with the notice that this could not be passed as a ref parameter because it is read-only. Fine then, I keep working and see that even without the ref keyword i can use the ref variable from the form, update some properties and see the changes. So whats happening here: passing a reference of the control to the helper method gives me ability to change its members even when not using the ref parameter?? Thanks.

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  • Calculating File size before download

    - by sagar
    Ok ! Coming to the point directly. What I want to do is explained as follows. I have an url of MP3 file. ( for example Sound File ) Now, When user starts application. Download should start & for that I have implemented following methods. -(void)viewDidLoad { [super viewDidLoad]; NSURL *url=[NSURL URLWithString:@"http://xyz.pqr.com/abc.mp3"]; NSURLRequest *req=[NSURLRequest requestWithURL:url cachePolicy:NSURLCacheStorageNotAllowed timeoutInterval:120]; NSURLConnection *con=[[NSURLConnection alloc] initWithRequest:req delegate:self startImmediately:YES]; if(con){ myWebData=[[NSMutableData data] retain]; } else { // [MainHandler performSelector:@selector(targetSelector:) withObject:nil]; } } -(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{ NSLog(@"%@",@"connection established"); [myWebData setLength: 0]; } -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { NSLog(@"%@",@"connection receiving data"); [myWebData appendData:data]; } -(void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { NSLog(@"%@",@"connection failed"); [connection release]; // [AlertViewHandler showAlertWithErrorMessage:@"Sorry, there is no network connection. Please check your network and try again."]; // [self parserDidEndDocument:nil]; } -(void)connectionDidFinishLoading:(NSURLConnection *)connection { [connection release]; } Now, Above methods work perfectly for downloading. But missing points are as follows. I can not get the exact size which is going to be downloaded. ( means I want to know what is the size of file - which is going to be download )

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  • PHP/Java Bridge - Access Java objects in PHP

    - by Omer Hassan
    I have a Red5 application which defines some public Java methods. When I start the server, an object of the application class gets created. I am trying to call the public methods of the application class from PHP using the existing instance of the Java application class. So here's my Java application: public class App extends org.red5.server.adapter.ApplicationAdapter { public boolean appStart(IScope app) { // This method gets called when the application starts // and an object of this App class is created. return true; } // This is the method I would like to call from PHP. public void f() { } } From PHP, I would like to get access to the App object that is created and call the method f() on it. I have tried playing around with this thing called "context". So in the Java method App.appStart(), I did this: // Save a reference to this App object to be retrieved later in PHP. new PhpScriptContextFactory().getContext().put("x", this); And in PHP, I tried to access the saved object like this: require_once("http://localhost:5080/JavaBridge/java/Java.inc"); var_dump(java_is_null(java_context()->get("x"))); Unfortunately, the java_is_null() function in PHP returns true. I also tried saving the App object in a static variable of App class but when I access that variable in PHP, its value is null.

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  • Php: Overriding abstract method goes wrong

    - by Lu4
    Hi! I think there is a problem in php's OOP implementation. EDIT: Consider more illustrative example: abstract class Animal { public $name; // public function Communicate(Animal $partner) {} // Works public abstract function Communicate(Animal $partner); // Gives error } class Panda extends Animal { public function Communicate(Panda $partner) { echo "Hi {$partner->name} I'm a Panda"; } } class Human extends Animal { public function Communicate(Human $partner) { echo "Hi {$partner->name} I'm a Human"; } } $john = new Human(); $john->name = 'John'; $mary = new Human(); $mary->name = 'Mary'; $john->Communicate($mary); // should be ok $zuzi = new Panda(); $zuzi->name = 'Zuzi'; $zuzi->Communicate($john); // should give error The problem is that when Animal::Communicate is an abstract method, php tells that the following methods are illegal: "public function Communicate(Panda $partner)" "public function Communicate(Human $partner)" but when Animal::Communicate is non-abstract but has zero-implementation Php thinks that these methods are legal. So in my opinion it's not right because we are doing override in both cases, and these both cases are equal, so it seems like it's a bug... Older part of the post: Please consider the following code: Framework.php namespace A { class Component { ... } abstract class Decorator { public abstract function Decorate(\A\Component $component); } } Implementation.php namespace B { class MyComponent extends \A\Component { ... } } MyDecorator.php namespace A { class MyDecorator extends Decorator { public function Decorate(\B\MyComponent $component) { ... } } } The following code gives error in MyDecorator.php telling Fatal error: Declaration of MyDecorator::Decorate() must be compatible with that of A\Decorator::Decorate() in MyDecorator.php on line ... But when I change the Framework.php::Decorator class to the following implementation: abstract class Decorator { public function Decorate(\A\Component $component) {} } the problem disappears.

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  • Get available screen area in autohotkey

    - by Herms
    I'm trying to write a few simple AutoHotkey scripts for moving windows around, and I'm having trouble getting the correct screen size values. I'm trying to get the size of the usable area on the screen (generally the full screen resolution minus the taskbar, and maybe any other docked windows like the sidebar in Vista). Neither of the methods I've found for getting the screen width seems to work. None of the 3 methods I found to get the screen size are giving me the right values. Here's the test script I'm using (running on XP with the taskbar on the bottom at its default size): #7:: WinMove A,,0,0,A_ScreenWidth,A_ScreenHeight return #8:: ;SM_CXMAXIMIZED and SM_CYMAXIMIZED SysGet, ScreenWidth, 61 SysGet, ScreenHeight, 62 WinMove A,,0,0,ScreenWidth,ScreenHeight return #9:: ;SM_CXFULLSCREEN and SM_CYFULLSCREEN SysGet, ScreenWidth, 16 SysGet, ScreenHeight, 17 WinMove A,,0,0,ScreenWidth,ScreenHeight return #7 causes the window to take up the entire resolution, so it overlaps the taskbar. #8 causes the width to be larger than the resolution (I see the window's right edge show up on my secondary monitor) and the height is slightly too large, so the window partially overlaps the taskbar area. Looks like this is correct except for not taking into account the window decorations at the edges. #9 seems to have the correct width, but the height is too short. It looks like it's subtracting the taskbar's height from the resolution's height, but then subtracting another 30 pixels from it. I could just use what I have in #9 and add 30 to the height I get, but that feels too much like a hack that would break in other configurations. It seems like there has to be a way to get the available screen size properly, but I can't find it in AutoHotkey. For reference, this seems to give me what I need in Java: Toolkit.getDefaultToolkit().getScreenSize();

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  • Using a class within a class?

    - by Josh
    I built myself a MySQL class which I use in all my projects. I'm about to start a project that is heavily based on user accounts and I plan on building my own class for this aswell. The thing is, a lot of the methods in the user class will be MySQL queries and methods from the MySQL class. For example, I have a method in my user class to update someone's password: class user() { function updatePassword($usrName, $newPass) { $con = mysql_connect('db_host', 'db_user', 'db_pass'); $sql = "UPDATE users SET password = '$newPass' WHERE username = '$userName'"; $res = mysql_query($sql, $con); if($res) return true; mysql_close($con); } } (I kind of rushed this so excuse any syntax errors :) ) As you can see that would use MySQL to update a users password, but without using my MySQL class, is this correct? I see no way in which I can use my MySQL class within my users class without it seeming dirty. Do I just use it the normal way like $DB = new DB();? That would mean including my mysql.class.php somewhere too... I'm quite confused about this, so any help would be appreciated, thanks.

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  • How to build a JSON response by combining @foo.to_json(options) and @bars.to_json(options) in Rails

    - by smotchkkiss
    First, the desired result I have User and Item models. I'd like to build a JSON response that looks like this: { "user": {"username":"Bob!","foo":"whatever","bar":"hello!"}, "items": [ {"id":1, "name":"one", "zim":"planet", "gir":"earth"}, {"id":2, "name":"two", "zim":"planet", "gir":"mars"} ] } However, my User and Item model have more attributes than just those. I found a way to get this to work, but beware, it's not pretty... Please help... My hacks home_controller.rb class HomeController < ApplicationController def observe respond_to do |format| format.js { render :json => Observation.new(current_user, @items).to_json } end end end observation.rb # NOTE: this is not a subclass of ActiveRecord::Base # this class just serves as a container to aggregate all "observable" objects class Observation attr_accessor :user, :items def initialize(user, items) self.user = user self.items = items end # The JSON needs to be decoded before it's sent to the `to_json` method in the home_controller otherwise the JSON will be escaped... # What a mess! def to_json { :user => ActiveSupport::JSON.decode(user.to_json(:only => :username, :methods => [:foo, :bar])), :items => ActiveSupport::JSON.decode(auctions.to_json(:only => [:id, :name], :methods => [:zim, :gir])) } end end

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  • Using ARIMA to model and forecast stock prices using user-friendly stats program

    - by Brian
    Hi people, Can anyone please offer some insight into this for me? I'm coming from a functional magnetic resonance imaging research background where I analyzed a lot of time series data, and I'd like to analyze the time series of stock prices (or returns) by: 1) modeling a successful stock in a particular market sector and then cross-correlating the time series of this historically successful stock with that of other newer stocks to look for significant relationships; 2) model a stock's price time series and use forecasting (e.g., exponential smoothing) to predict future values of it. I'd like to use non-linear modeling methods (ARIMA and ARCH) to do this. Several questions: How often do ARIMA and ARCH modeling methods (given that the individual who implements them does so accurately) actually fit the stock time series data they target, and what is the optimal fit I can expect? Is the extent to which this model fits the data commensurate with the extent to which it predicts this stock time series' future values? Rather than randomly selecting stocks to compare or model, if profit is my goal, what is an efficient approach, if any, to selecting the stocks I'm going to analyze? Which stats program is the most user-friendly for this? Any thoughts on this would be great and would go a long way for me. Thanks, Brian

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  • My app crashes after multiple rotates

    - by Ian Rae
    My app is crashing when I try and rotate it more than a couple of times. I first thought it was just the iPhone Simulator, so I loaded the app onto an iPod touch, and it crashed after fewer rotates in a row. I suspect it's a memory leak in one of my rotate methods. The only place I can think that the crash is being caused is in willRotateToInterfaceOrientation:duration:. The only two methods related to rotate that I've added/extended are shouldAutorotateToInterfaceOrientation: and willRotateToInterfaceOrientation:duration and I don't think it's the first because it only contains the two words: return YES;. Here is my willRotateToInterfaceOrientation:duration: method so you can review it and see where the possible memory leak is. -(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)orientation duration:(NSTimeInterval)duration { UIFont *theFont; if ((orientation == UIInterfaceOrientationLandscapeLeft) || (orientation == UIInterfaceOrientationLandscapeRight)) { theFont = [yearByYear.font fontWithSize:16.0]; yearByYear.font = theFont; [theview setContentSize:CGSizeMake(460.0f, 635.0f)]; } else { theFont = [yearByYear.font fontWithSize:10.0]; yearByYear.font = theFont; [theview setContentSize:CGSizeMake(300.0f, 460.0f)]; } [theFont release]; } yearByYear is a UITextView theview is a UIScrollView if anyone has any idea of why my app is crashing, I would be greatly appreciative.

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  • LINQtoSQL Custom Constructor off Partial Class?

    - by sah302
    Hi all, I read this question here: http://stackoverflow.com/questions/82409/is-there-a-way-to-override-the-empty-constructor-in-a-class-generated-by-linqtosq Typically my constructor would look like: public User(String username, String password, String email, DateTime birthday, Char gender) { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, as read in that question, you want to use partial method OnCreated() instead to assign values and not overwrite the default constructor. Okay so I got this : partial void OnCreated() { this.Id = Guid.NewGuid(); this.DateCreated = this.DateModified = DateTime.Now; this.Username = username; this.Password = password; this.Email = email; this.Birthday = birthday; this.Gender = gender; } However, this gives me two errors: Partial Methods must be declared private. Partial Methods must have empty method bodies. Alright I change it to Private Sub OnCreated() to remove both of those errors. However I am still stuck with...how can I pass it values as I would with a normal custom constructor? Also I am doing this in VB (converted it since I know most know/prefer C#), so would that have an affect on this?

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  • java partial classes

    - by Dewfy
    Hello colleagues, Small preamble. I was good java developer on 1.4 jdk. After it I have switched to another platforms, but here I come with problem so question is strongly about jdk 1.6 (or higher :) ). I have 3 coupled class, the nature of coupling concerned with native methods. Bellow is example of this 3 class public interface A { public void method(); } final class AOperations { static native method(. . .); } public class AImpl implements A { @Override public void method(){ AOperations.method( . . . ); } } So there is interface A, that is implemented in native way by AOperations, and AImpl just delegates method call to native methods. These relations are auto-generated. Everything ok, but I have stand before problem. Sometime interface like A need expose iterator capability. I can affect interface, but cannot change implementation (AImpl). Saying in C# I could be able resolve problem by simple partial: (C# sample) partial class AImpl{ ... //here comes auto generated code } partial class AImpl{ ... //here comes MY implementation of ... //Iterator } So, has java analogue of partial or something like.

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  • Multi-level shop, xml or sql. best practice?

    - by danrichardson
    Hello, i have a general "best practice" question regarding building a multi-level shop, which i hope doesn't get marked down/deleted as i personally think it's quite a good "subjective" question. I am a developer in charge (in most part) of maintaining and evolving a cms system and associated front-end functionality. Over the past half year i have developed a multiple level shop system so that an infinite level of categories may exist down into a product level and all works fine. However over the last week or so i have questioned by own methods in front-end development and the best way to show the multi-level data structure. I currently use a sql server database (2000) and pull out all the shop levels and then process them into an enumerable typed list with child enumerable typed lists, so that all levels are sorted. This in my head seems quite process heavy, but we're not talking about thousands of rows, generally only 1-500 rows maybe. I have been toying with the idea recently of storing the structure in an XML document (as well as the database) and then sending last modified headers when serving/requesting the document for, which would then be processed as/when nessecary with an xsl(t) document - which would be processed server side. This is quite a handy, reusable method of storing the data but does it have more overheads in the fact im opening and closing files? And also the xml will require a bit of processing to pull out blocks of xml if for instance i wanted to show two level mid way through the tree for a side menu. I use the above method for sitemap purposes so there is currently already code i have built which does what i require, but unsure what the best process is to go about. Maybe a hybrid method which pulls out the data, sorts it and then makes an xml document/stream (XDocument/XmlDocument) for xsl processing is a good way? - This is the way i currently make the cms work for the shop. So really (and thanks for sticking with me on this), i am just wandering which methods other people use or recommend as being the best/most logical way of doing things. Thanks Dan

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  • ASP.NET MVC UpdateModel doesn't update inherited public properties??

    - by mrjoltcola
    I refactored some common properties into a base class and immediately my model updates started failing. UpdateModel() and TryUpdateModel() do not seem to update inherited public properties. I cannot find detailed info on MSDN nor Google as to the rules or semantics of these methods. The docs are terse (http://msdn.microsoft.com/en-us/library/dd470933.aspx), simply stating: Updates the specified model instance using values from the controller's current value provider. Well that leads us to believe it is as simple as that. It makes no mention of limitations with inheritance. My assumption is the methods are reflecting on the top class only, ignoring base properties, but this seems to be an ugly shortcoming, if so. SOLVED: Eep, this turned out to have nothing to do with inheritance. My base class was implemented with public fields, not properties. Switching them to formal properties (adding {get; set; }) was all I needed. This has bitten me before, I keep wanting to use simple, public fields.

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  • WCF service with PHP client - complex type as parameter not working

    - by Matt F
    Hi, I have a WCF service with three methods. Two of the methods return custom types (these work as expected), and the third method takes a custom type as a parameter and returns a boolean. When calling the third method via a PHP soap client it returns an 'Object reference not set to an instance of an object' exception. Example Custom Type: _ Public Class MyClass Private _propertyA As Double <DataMember()> _ Public Property PropertyA() As Double Get Return _propertyA End Get Set(ByVal value As Double) _propertyA = value End Set End Property Private _propertyB As Double <DataMember()> _ Public Property PropertyB() As Double Get Return _propertyB End Get Set(ByVal value As Double) _propertyB = value End Set End Property Private _propertyC As Date <DataMember()> _ Public Property PropertyC() As Date Get Return _propertyC End Get Set(ByVal value As Date) _propertyC = value End Set End Property End Class Method: Public Function Add(ByVal param As MyClass) As Boolean Implements IService1.Add ' ... End Function PHP client call: $client-Add(array('param'=array( 'PropertyA' = 1, 'PropertyB' = 2, 'PropertyC' = "2009-01-01" ))); The WCF service works fine with a .Net client but I'm new to PHP and can't get this to work. Is it possible to create an instance of 'MyClass' in PHP. Any help would be appreciated. Note: I'm using PHP 5 (XAMPP 1.7.0 for Windows). Thanks Matt

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  • Generating JavaScript in C# and subsequent testing

    - by Codebrain
    We are currently developing an ASP.NET MVC application which makes heavy use of attribute-based metadata to drive the generation of JavaScript. Below is a sample of the type of methods we are writing: function string GetJavascript<T>(string javascriptPresentationFunctionName, string inputId, T model) { return @"function updateFormInputs(value){ $('#" + inputId + @"_SelectedItemState').val(value); $('#" + inputId + @"_Presentation').val(value); } function clearInputs(){ " + helper.ClearHiddenInputs<T>(model) + @" updateFormInputs(''); } function handleJson(json){ clearInputs(); " + helper.UpdateHiddenInputsWithJson<T>("json", model) + @" updateFormInputs(" + javascriptPresentationFunctionName + @"()); " + model.GetCallBackFunctionForJavascript("json") + @" }"; } This method generates some boilerplace and hands off to various other methods which return strings. The whole lot is then returned as a string and written to the output. The question(s) I have are: 1) Is there a nicer way to do this other than using large string blocks? We've considered using a StringBuilder or the Response Stream but it seems quite 'noisy'. Using string.format starts to become difficult to comprehend. 2) How would you go about unit testing this code? It seems a little amateur just doing a string comparison looking for particular output in the string. 3) What about actually testing the eventual JavaScript output? Thanks for your input!

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  • how to use Remote Service ?

    - by LEE YONGGUN
    Hi im trying to use Remote Service btween two simple application, But its not easy to me. So any advice you have will help me. here`s my case. I made one app which is playing Music in service, There are two components. one is Activity controlling service by using three buttons, play,pause, stop. and it is working fine. and another one is just simple Activity which also has four buttons bind,play,stop,unbind. when i click bind, it`s confirmed by Toast msg, but when i click play button,it occurs error. i want to control first activitys Music playing service in second Activity. So im trying to use remote service. i made same .aidl file in each app project. In aidl file, i defined methods "playing","stoping" and i implement those methods in Music service class, implementation is simply use intent and startService & stopService. In DDMS there is "java.lang.SecurityException : Binder invocation to an incorrect interface" thats the case what im doing. So please tell me what`s the problem. any advice could help me. thanks Gun.

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  • Can I use the auto-generated Linq-to-SQL entity classes in 'disconnected' mode?

    - by Gary McGill
    Suppose I have an automatically-generated Employee class based on the Employees table in my database. Now suppose that I want to pass employee data to a ShowAges method that will print out name & age for a list of employees. I'll retrieve the data for a given set of employees via a linq query, which will return me a set of Employee instances. I can then pass the Employee instances to the ShowAges method, which can access the Name & Age fields to get the data it needs. However, because my Employees table has relationships with various other tables in my database, my Employee class also has a Department field, a Manager field, etc. that provide access to related records in those other tables. If the ShowAges method were to invoke any of those methods, this would cause lots more data to be fetched from the database, on-demand. I want to be sure that the ShowAges method only uses the data I have already fetched for it, but I really don't want to have to go to the trouble of defining a new class which replicates the Employee class but has fewer methods. (In my real-world scenario, the class would have to be considerably more complex than the Employee class described here; it would have several 'joined' classes that do need to be populated, and others that don't). Is there a way to 'switch off' or 'disconnect' the Employees instances so that an attempt to access any property or related object that's not already populated will raise an exception? If not, then I assume that since this must be a common requirement, there might be an already-established pattern for doing this sort of thing?

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  • why won't Eclipse use the compiler I specify for my project?

    - by codeman73
    I'm using Eclipse 3.3. In my project, I've set the compiler compliance level to 5.0 In the build path for the project. I've added the Java 1.5 JDK in the Installed JREs section and am referencing that System Library in my project build path. However, I'm getting compile errors for a class that implements PreparedStatement for not implementing abstract methods that only exist in Java 1.6 PreparedStatement. Specifically, the methods setAsciiStream(int, InputStream, long) and setAsciiStream(int, InputStream) Strangely enough, it worked when we were compiling it against Java 1.4, which it was originally written for. We added the JREs for Java 1.4 and referenced that system library in the project, and set the project's compiler level to 1.4, and it works fine. But when I do the same changes to try to point to Java 5.0, it instead uses Java 6. Any ideas why? I wrote a similar question earlier, here: http://stackoverflow.com/questions/2540548/how-do-i-get-eclipse-to-use-a-different-compiler-version-for-java I know how you're supposed to choose a different compiler but it seems Eclipse isn't taking it. It seems to be defaulting to Java 6, even though I have deleted all Java 6 JDKs and JREs that I could find. I've also updated the -vm option in my eclipse.ini to point to the Java5 JDK.

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  • ASP.NET MVC static-asset aides/practices

    - by shannon
    I want to keep assets that are only used by one view in a view-specific folder, so my Search.aspx properly finds images/*.jpg, and helps me maintain my convention: ~/Areas/Candidate/Views/Job/Search.aspx -> ~/Assets/Candidate/Job/Search/images/*.jpg Perhaps with the ability to easily reference controller- or area-common assets manually or automatically: ~/Assets/Candidate/Job/images/*.jpg ~/Assets/Candidate/images/*.jpg If you wonder why I'm doing this, then speak up; I'm probably missing something. But here's why: I don't want stale static assets sitting in my ASP.NET MVC projects, which I expect to be an automatic outcome of the ~/Assets/Images folder: i.e. As a shared asset loses its last reference-count, who knows to delete it, especially with it being so difficult to trace content link validity in MVC projects? How do you, personally, do this? I can imagine, for example: Implement HtmlHelper extension methods for URL-generation. Extending ViewPage and ViewMasterPage with URL-generation methods. Implementing an inbound request filter to search related folders for static assets. and, are there good libraries out there for this? For example, something that also automatically appends timestamps for .JS and .CSS files, writes the / tags for me, and maybe even that allows me to inject includes in the head section from outside head code?

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  • debugging scaffolding contingent upon degbugging boolean (java)

    - by David
    Recently i've found myself writing a lot of methods with what i can only think to call debugging scaffolding. Here's an example: public static void printArray (String[] array, boolean bug) { for (int i = 0; i<array.lenght; i++) { if (bug) System.out.print (i) ; //this line is what i'm calling the debugging scaffolding i guess. System.out.println(array[i]) ; } } in this method if i set bug to true, wherever its being called from maybe by some kind of user imput, then i get the special debugging text to let me know what index the string being printed as at just in case i needed to know for the sake of my debugging (pretend a state of affairs exists where its helpful). All of my questions more or less boil down to the question: is this a good idea? but with a tad bit more objectivity: Is this an effective way to test my methods and debug them? i mean effective in terms of efficiency and not messing up my code. Is it acceptable to leave the if (bug) stuff ; code in place after i've got my method up and working? (if a definition of "acceptability" is needed to make this question objective then use "is not a matter of programing controversy such as ommiting brackets in an if(boolean) with only one line after it, though if you've got something better go ahead and use your definition i won't mind) Is there a more effective way to accomplish the gole of making debugging easier than what i'm doing? Anything you know i mean to ask but that i have forgotten too (as much information as makes sense is appreciated).

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  • Ruby and duck typing: design by contract impossible?

    - by davetron5000
    Method signature in Java: public List<String> getFilesIn(List<File> directories) similar one in ruby def get_files_in(directories) In the case of Java, the type system gives me information about what the method expects and delivers. In Ruby's case, I have no clue what I'm supposed to pass in, or what I'll expect to receive. In Java, the object must formally implement the interface. In Ruby, the object being passed in must respond to whatever methods are called in the method defined here. This seems highly problematic: Even with 100% accurate, up-to-date documentation, the Ruby code has to essentially expose its implementation, breaking encapsulation. "OO purity" aside, this would seem to be a maintenance nightmare. The Ruby code gives me no clue what's being returned; I would have to essentially experiment, or read the code to find out what methods the returned object would respond to. Not looking to debate static typing vs duck typing, but looking to understand how you maintain a production system where you have almost no ability to design by contract. Update No one has really addressed the exposure of a method's internal implementation via documentation that this approach requires. Since there are no interfaces, if I'm not expecting a particular type, don't I have to itemize every method I might call so that the caller knows what can be passed in? Or is this just an edge case that doesn't really come up?

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  • Invalid method declaration, return type required

    - by Brett Steen
    I am getting an error at public Rectangle(double width, double height){ saying that it's an invalid method declaration, return type required. I'm not sure how to fix it. These are also my instructions for my assignment: Write a super class encapsulating a rectangle. A rectangle has two attributes representing the width and the height of the rectangle. It has methods returning the perimeter and the area of the rectangle. This class has a subclass, encapsulating a parallelepiped, or box. A parallelepiped has a rectangle as its base, and another attribute, its length. It has two methods that calculate and return its area and volume. `public class Rectangle1 { private double width; private double height; public Rectangle1(){ } public Rectangle(double width, double height){ this.width = width; this.height = height; } public double getWidth(){ return width; } public void setWidth(double width) { this.width = width; } public double getHeight(){ return height; } public void setHeight(double height){ this.height = height; } public double getArea(){ return width * height; } public double getPerimeter(){ return 2 * (width + height); } } public class TestRectangle { public static void main(String[] args) { Rectangle1 rectangle = new Rectangle1(2,4); System.out.println("\nA rectangle " + rectangle.toString()); System.out.println("The area is " + rectangle.getArea()); System.out.println("The perimeter is " + rectangle.getPerimeter()); } }`

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  • How do I apply a "template" or "skeleton" of code in C# here?

    - by Scott Stafford
    In my business layer, I need many, many methods that follow the pattern: public BusinessClass PropertyName { get { if (this.m_LocallyCachedValue == null) { if (this.Record == null) { this.m_LocallyCachedValue = new BusinessClass( this.Database, this.PropertyId); } else { this.m_LocallyCachedValue = new BusinessClass( this.Database, this.Record.ForeignKeyName); } } return this.m_LocallyCachedValue; } } I am still learning C#, and I'm trying to figure out the best way to write this pattern once and add methods to each business layer class that follow this pattern with the proper types and variable names substituted. BusinessClass is a typename that must be substituted, and PropertyName, PropertyId, ForeignKeyName, and m_LocallyCachedValue are all variables that should be substituted for. Are attributes usable here? Do I need reflection? How do I write the skeleton I provided in one place and then just write a line or two containing the substitution parameters and get the pattern to propagate itself? EDIT: Modified my misleading title -- I am hoping to find a solution that doesn't involve code generation or copy/paste techniques, and rather to be able to write the skeleton of the code once in a base class in some form and have it be "instantiated" into lots of subclasses as the accessor for various properties. EDIT: Here is my solution, as suggested but left unimplemented by the chosen answerer. // I'll write many of these... public BusinessClass PropertyName { get { return GetSingleRelation(ref this.m_LocallyCachedValue, this.PropertyId, "ForeignKeyName"); } } // That all call this. public TBusinessClass GetSingleRelation<TBusinessClass>( ref TBusinessClass cachedField, int fieldId, string contextFieldName) { if (cachedField == null) { if (this.Record == null) { ConstructorInfo ci = typeof(TBusinessClass).GetConstructor( new Type[] { this.Database.GetType(), typeof(int) }); cachedField = (TBusinessClass)ci.Invoke( new object[] { this.Database, fieldId }); } else { var obj = this.Record.GetType().GetProperty(objName).GetValue( this.Record, null); ConstructorInfo ci = typeof(TBusinessClass).GetConstructor( new Type[] { this.Database.GetType(), obj.GetType()}); cachedField = (TBusinessClass)ci.Invoke( new object[] { this.Database, obj }); } } return cachedField; }

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  • Conditional macro expansion

    - by Dave DeLong
    Heads up: This is a weird question. I've got some really useful macros that I like to use to simplify some logging. For example I can do Log(@"My message with arguments: %@, %@, %@", @"arg1", @"arg2", @"arg3"), and that will get expanded into a more complex method invocation that includes things like self, _cmd, __FILE__, __LINE__, etc, so that I can easily track where things are getting logged. This works great. Now I'd like to expand my macros to not only work with Objective-C methods, but general C functions. The problem is the self and _cmd portions that are in the macro expansion. These two parameters don't exist in C functions. Ideally, I'd like to be able to use this same set of macros within C functions, but I'm running into problems. When I use (for example) my Log() macro, I get compiler warnings about self and _cmd being undeclared (which makes total sense). My first thought was to do something like the following (in my macro): if (thisFunctionIsACFunction) { DoLogging(nil, nil, format, ##__VA_ARGS__); } else { DoLogging(self, _cmd, format, ##__VA_ARGS__); } This still produces compiler warnings, since the entire if() statement is substituted in place of the macro, resulting in errors with the self and _cmd keywords (even though they will never be executed during function execution). My next thought was to do something like this (in my macro): if (thisFunctionIsACFunction) { #define SELF nil #define CMD nil } else { #define SELF self #define CMD _cmd } DoLogging(SELF, CMD, format, ##__VA_ARGS__); That doesn't work, unfortunately. I get "error: '#' is not followed by a macro parameter" on my first #define. My other thought was to create a second set of macros, specifically for use in C functions. This reeks of a bad code smell, and I really don't want to do this. Is there some way I can use the same set of macros from within both Objective-C methods and C functions, and only reference self and _cmd if the macro is in an Objective-C method?

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  • Android custom view - setting it to take up max space available but no more

    - by Rich
    I have a custom View class in my app that I'm using in xml layouts. Wherever I'm using this view in my xml, I don't want it to stretch it's container, but I want it to fill out whatever space is available. Here's an example to make it a little clearer. I have a LinearLayout set to horizontal orientation with my custom view followed by a TextView. The TextView is going to stretch the LinearLayout so that it takes up the space it needs and no more. I want my custom view to take up the vertical space that the TextView has made available. Let's say the TextView ends up being 50px tall because of it's contents. The LinearLayout is thus stretched to about this height (not taking into account any margins or padding), so I just want the view to know it can stretch to that height and not "push on" its container. Without overriding and of the measurement methods of the base class (onMeasure, etc) my View is actually stretching to take up as much space as possible. I have already played around with wrap_content and fill_parent a bunch, so I'm assuming I need to do something in one of the View class' measure methods.

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