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  • In need of a good MATLAB class tutorial

    - by rlbond
    I'm having a lot of trouble trying to figure out how to use classes in MATLAB. I'm very familiar with C++ and Python but I just can't figure anything out about how to define classes in MATLAB. Does anyone know a very good resource with lots of examples? The official documentation leaves much to be desired.

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  • Reference variable to an object instantiated/initialized in another class in Java

    - by Alex
    The reason I'm asking is because I'm getting NullPointerException. I now this is very easy but I'm pretty new programming and find this a bit confusing. So say I have initialized an object in a class and want to access that same object from another class. Like now for instance I'm working on a small Chess game, in my model Game class I have an instance of Board, an object. Board, in turn, has an array of Squares. Square[][]. Game has board, board has Square[][]. Now if I want to access the Square[][] through the object board (in Game) of type Board. Do I just declare a variable with the same name and type or do I have to initialize it again? Board board OR Board board = new Board(); Note, I have already initialized board in the class Game so if I do it again, won't they be two totally different Board objects?

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  • PHP 5 functioning returning an array- interaction without assignment?

    - by Lee
    I'm wondering if this kind of thing will ever be possible in PHP (and whether it already is and I'm just missing something...) <?php function test() { return array( 'id'=>10, 'name'=>'John' ); } echo 'Your name is: '.test()['name']; ?> I'd really like to be able to use returned arrays directly instead of first assigning them to a var... possible?

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  • java swt design patterns

    - by zachary
    What are some good design patterns for creating a form in java? I have an app that has 6 tabs with a different form in each. How does the typical java programmer go about making these items accessible? For example as a wpf programmer I might databind all these controls to underlying objects. What do java programmers like to do?

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  • I'd want a method to be called only by objects of a specific class

    - by mp
    Suppose you have this class: public class A { private int number; public setNumber(int n){ number = n; } } I'd like the method setNumber could be called only by objects of a specific class. Does it make sense? I know it is not possible, is it? Which are the design alternatives? Some well known design pattern? Sorry for the silly question, but I'm a bit rusty in OO design.

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  • Pass object from webserver to client

    - by user362914
    I developed a C# web application that calls a web-service which returns a base64 encoded array (PDF file). I then convert that array into a UCOMIStream object (I know it is obsolete, but the DLL that I am using requires it as a parameter). I use the following code to do the conversion which works perfectly. I can pass this object to the DLL so that I can print the PDF. This works great on the Webserver, but the requirement is to print it locally. Byte[] bBuffer = statementOut.statementcycle.statementdata.content; int size = bBuffer.Length; IntPtr mem = Marshal.AllocHGlobal(size); Marshal.Copy(bBuffer, 0, mem, size); // Create an OLE Stream object. System.Runtime.InteropServices.UCOMIStream str; //obsolete but the createstreamonhglobal outputs it CreateStreamOnHGlobal(mem, true, out str); The DLL resides on the client so I am able to use ActiveX to create the object using javascript and/or VBscript;however, I have not been able to figure out how to get the stream object to the client to pass to the DLL. How can this be achieved?

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  • Reference an object, based on a variable with it's name in it

    - by James G
    I'm looking for a way to reference an object, based on a variable with it's name in it. I know I can do this for properties and sub properties: var req = {body: {jobID: 12}}; console.log(req.body.jobID); //12 var subProperty = "jobID"; console.log(req.body[subProperty ]); //12 var property = "body"; console.log(req[property][subProperty]); //12 is it possible for the object itself? var req = {body: {jobID: 12}}; var object = "req"; var property = "body"; var subProperty = "jobID"; console.log([object][property][subProperty]); //12 or console.log(this[object][property][subProperty]); //12 Note: I'm doing this in node.js not a browser. Here is an exert from the function: if(action.render){ res.render(action.render,renderData); }else if(action.redirect){ if(action.redirect.args){ var args = action.redirect.args; res.redirect(action.redirect.path+req[args[0]][args[1]]); }else{ res.redirect(action.redirect.path); } } I could work around it by changing it to this, but I was looking for something more dynamic. if(action.render){ res.render(action.render,renderData); }else if(action.redirect){ if(action.redirect.args){ var args = action.redirect.args; if(args[0]==="req"){ res.redirect(action.redirect.path+req[args[1]][args[2]]); }else if(args[0]==="rows"){ rows.redirect(action.redirect.path+rows[args[1]][args[2]]); } }else{ res.redirect(action.redirect.path); } }

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  • What is the Rule of Thumb on Exposing Encapsulated Class Methods

    - by javamonkey79
    Consider the following analogy: If we have a class: "Car" we might expect it to have an instance of "Engine" in it. As in: "The car HAS-A engine". Similarly, in the "Engine" class we would expect an instance of "Starting System" or "Cooling System" which each have their appropriate sub-components. By the nature of encapsulation, is it not true that the car "HAS-A" "radiator hose" in it as well as the engine? Therefore, is it appropriate OO to do something like this: public class Car { private Engine _engine; public Engine getEngine() { return _engine; } // is it ok to use 'convenience' methods of inner classes? // are the following 2 methods "wrong" from an OO point of view? public RadiatorHose getRadiatorHose() { return getCoolingSystem().getRadiatorHose(); } public CoolingSystem getCoolingSystem() { return _engine.getCoolingSystem(); } } public class Engine { private CoolingSystem _coolingSystem; public CoolingSystem getCoolingSystem() { return _coolingSystem; } } public class CoolingSystem { private RadiatorHose _radiatorHose; public RadiatorHose getRadiatorHose() { return _radiatorHose; } } public class RadiatorHose {//... }

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  • Can't declare an abstract method private....

    - by Zombies
    I want to do this, yet I can't. Here is my scenario and rational. I have an abstract class for test cases that has an abstract method called test(). The test() method is to be defined by the subclass; it is to be implemented with logic for a certain application, such as CRMAppTestCase extends CompanyTestCase. I don't want the test() method to be invoked directly, I want the super class to call the test() method while the sub class can call a method which calls this (and does other work too, such as setting a current date-time right before the test is executed for example). Example code: public abstract class CompanyTestCase { //I wish this would compile, but it cannot be declared private private abstract void test(); public TestCaseResult performTest() { //do some work which must be done and should be invoked whenever //this method is called (it would be improper to expect the caller // to perform initialization) TestCaseResult result = new TestCaseResult(); result.setBeginTime(new Date()); long time = System.currentTimeMillis(); test(); //invoke test logic result.setDuration(System.currentTimeMillis() - time); return result; } } Then to extend this.... public class CRMAppTestCase extends CompanyTestCase { public void test() { //test logic here } } Then to call it.... TestCaseResult result = new CRMAppTestCase().performTest();

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  • Why can't I create an abstract constructor on an abstract C# class?

    - by Anthony D
    I am creating an abstract class. I want each of my derived classes to be forced to implement a specific signature of constructor. As such, I did what I would have done has I wanted to force them to implement a method, I made an abstract one. public abstract class A { abstract A(int a, int b); } However I get a message saying the abstract modifier is invalid on this item. My goal was to force some code like this. public class B : A { public B(int a, int b) : base(a, b) { //Some other awesome code. } } This is all C# .NET code. Can anyone help me out? Update 1 I wanted to add some things. What I ended up with was this. private A() { } protected A(int a, int b) { //Code } That does what some folks are saying, default is private, and the class needs to implement a constructor. However that doesn't FORCE a constructor with the signature A(int a, int b). public abstract class A { protected abstract A(int a, int b) { } } Update 2 I should be clear, to work around this I made my default constructor private, and my other constructor protected. I am not really looking for a way to make my code work. I took care of that. I am looking to understand why C# does not let you do this.

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  • PHP Store User Data without Sessions

    - by Sev
    Is there anyway to store users data such as userid, email, etc to be accessible from all pages of a website after they have logged in, but without using sessions or cookies? For example: class User { var $userid; var $username; var $email; .. methods.. } after they login at login.php $currentUser = new User($_POST['username']) now, how do I access $currentUser from another page, such as index.php if I shouldn't use sessions or cookies at all? so that I could do the following in index.php: if ($currentUser->userid > -1) { echo "you are logged in as: " . $currentUser->username; } else { echo "click here to login"; } i asked a similar question before, here, but the answers didn't fulfill my needs.

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  • Simple OOP-related question.

    - by M4design
    This question came to my mind quite a few times. Let my explain my question through an example. Say I've got two classes: 1- Grid. 2- Cell. Now the location of the cell 'should' be stored in the grid class, not in the cell class itself. Say that the cell wanted to get its location through a method in the grid. How can it do that? Keep in mind that the cell was created/initialised by the Grid class. What good OO approach to solve this problem? Thank you

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  • Calling a method on a Object says "disallows late binding"

    - by Maury Markowitz
    I have a calls called DtaDate that stores an integer "key", a string name, a string for the date, and a Date object that is created from that string. I have some code that needs to accept a date-like object. I'd like the user to be able to pass in anything date like - a Date object which I'll extract the information from, another DtaDate, a string with the date in it, or even the key, which I'll use to look up the DtaDate from a collection. So I have this: Friend Sub New(NameIn As String, DateFormulaIn As String, Optional FromDateIn As Object = Nothing) [stuff that works] [check that we got a FromDateIn...] If TypeOf FromDateIn Is DtaDate Then fdk = FromDateIn.Key Ans.FromDate = fdk VB tells me that "Option Strict On disallows late binding". The other cases, where a string or integer is the TypeOf, I use CInt or CStr. But this is the first time I've actually run into a case where the casting is a non-base type. What's the trick?

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  • Rails - before_filter than includes updated object

    - by Sam
    I have a before filter than calculates a percentage that needs to include the object that is being updated. Is there a one liner in rails that takes care of this? for example and this is totaly made up: Object.find(:all, :include = :updated_object) Currently I'm sending the object that is getting updated to the definition that calculates the percentage and that works but its making things messy.

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  • a design to avoid circular reference in this scenario

    - by BDotA
    Here is our dependency tree: BigApp - Child Apps - Libraries ALL of our components are HEAVILY using one of the Libraries as above ( LibA). But it has a ‘few’ public methods that require classes from ‘higher-level’ assemblies and we want to avoid CIRCULAR references. What do you propose as a good design for this?

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  • How to simplify the code?

    - by Tattat
    I have objectA, and objectB.... also I have objectAs, and objectBs. the objectA is only have the init method, and ObjectAs have somethings like this: #import "ObjectAs.h" @implementation ObjectAs @synthesize objectAs; -(id) init{ if( (self=[super init])) { self.objectAs = [[NSMutableArray alloc] init]; } return self; } -(int)getObjectAsNumber{ return [self.objectAs count]; } -(void)addObjectA:(ObjectA *)newObjectA{ [self.objectAs addObject:newObjectA]; } -(id)getObjectAByIdx:(int)objectAIdx{ return [self.objectAs objectAtIndex:objectAIdx]; } -(void)dealloc{ [super dealloc]; [objectAs release]; } @end The objectBs have similar have, I know that I can copy and paste, and replace it. Is there any way to simplify the objectBs, and objectAs? thz a lot.

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  • Unstructured database design

    - by Linh
    Hi all, According to normal way, we design the table with fields. Example with an article the table can contain fields as follows: title, content, author..... But how does everybody think if we add up some fields to a field?

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  • String Object. Clarification needed

    - by mac
    Guys, help me clarify. Say i have the following line in my program: jobSetupErrors.append("abc"); In the case above where jobSetupErrors is a StringBuilder(), what i see happen is: New String Object is created and assigned value "abc" value of that String object is assigned to the existing StringBuilder object If that is correct, and I add 1 more line ... jobSetupErrors.append("abc"); logger.info("abc"); In the above example are we creating String object separately 2 times? If so, would it be more proper to do something like this? String a = "abc"; jobSetupErrors.append(a); logger.info(a); Is this a better approach? Please advise

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  • DateTime object is blank

    - by user522962
    I am trying to convert a date to a DateTime Object. My code works fine on my localhost (php version 5.3) but returns a blank DateTime object on my remote server (php version 5.2.14). Am I missing something really obvious? <?php $d = '2010-01-01'; $n = new DateTime ( $d ); print_r($n); ?> // result on localhost: DateTime Object ( [date] => 2010-01-01 00:00:00 [timezone_type] => 3 [timezone] => UTC ) // result on remotehost: DateTime Object ( ) // is blank

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  • TDBGrid columns design time or run time?

    - by Mawg
    I am using TDBGrid for the first time. I didn't even notice the Columns property in the object inspector and everything went just fine: the grid was filled. Then I saw the Columns property and tried it. When I use the object insector to add items to the Columns property of the grid, they do not all of them show up at run time. To me, it looks like the FieldName property is important. It looks like it is correct, but there are no values in some columns. If I leave this property blank (no columns at all) it seems that the control populates it itself at run time and I do see all the columns. I could live with that. When I set column titles at run time it works, but setting column width does not.

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