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  • When exactly does a method have side effects?

    - by Kim
    As I always understood it, any change to the programs state (or anything to do with IO) is a side effect. It does not matter, whether the change occurs in a global variable or in a private field of the object the method is called on. It follows that all methods which do not return anything either do nothing at all or have a side effect. My confusion comes from one of our university's instructors (who is still a student and thus not omniscient yet;) ) telling me setters don't have side effects.

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  • LINQ to sql return group by results from method

    - by petebob796
    How do I create a method to return the results of a group by in LINQ to sql such as the one below: internal SomeTypeIDontKnow GetDivisionsList(string year) { var divisions = from p in db.cm_SDPs where p.acad_period == year group p by new { p.Division } into g select new { g.Key.Division }; return divisions; } I can't seem to define a correct return type. I think it is because it's an anonymous type but haven't got my head around it yet. Do I need to convert it to a list or something? The results would just be used for filling a combo box.

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  • Sending string from class to Form1

    - by Farstucker
    Although there are some similar questions I’m having difficulties finding an answer on how to receive data in my form from a class. I have been trying to read about instantiation and its actually one of the few things that does make sense to me :) but if I were to instantiate my form, would I not have two form objects? To simplify things, lets say I have a some data in Class1 and I would like to pass a string into a label on Form1. Is it legal to instantiate another form1? When trying to do so it looks like I can then access label1.Text but the label isn’t updating. The only thing I can think of is that the form needs to be redrawn or there is some threading issue that I’m unaware of. Any insight you could provide would be greatly appreciated.

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  • Add a listener inside or outside get method

    - by James P.
    I'm learning Swing and have composed an interface using a series of get methods to add components. Is it a good practise to add a Listener inside a get method as follows? I'd like to make things as decoupled as possible. private JButton getConnectButton() { if (connectButton == null) { connectButton = new JButton(); connectButton.setText("Connect"); connectButton.setSize(new Dimension(81, 16)); connectButton.setLocation(new Point(410, 5)); connectButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { // actionPerformed code goes here } }); } return connectButton; }

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  • LINQ-to-SQL class doesn't implement INotifyPropertyChanging & INotifyPropertyChanged if pulling from

    - by Traples
    I modified my data source in my LINQ-to-SQL class (by the old delete and drag back in method), and was surprised to see the INotifyPropertyChanging & INotifyPropertyChanged interfaces no longer implemented in the generated classes (MyDb.designer.cs). The methods for the individual fields went from looking like this... [Column(Storage="_Size", DbType="NVarChar(100)")] public string Size { get { return this._Size; } set { if ((this._Size != value)) { this.OnSizeChanging(value); this.SendPropertyChanging(); this._Size = value; this.SendPropertyChanged("Size"); this.OnSizeChanged(); } } } To looking like this... [Column(Storage="_Size", DbType="NVarChar(100)")] public string Size { get { return this._Size; } set { if ((this._Size != value)) { this._Size = value; } } } Any ideas on why this happens and how it will affect my application?

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  • Clone existing structs with different alignment in Visual C++

    - by Crend King
    Is there a way to clone an existing struct with different member alignment in Visual C++? Here is the background: I use an 3rd-party library, which uses several structs. To fill up the structs, I pass the address of the struct instances to some functions. Unfortunately, the functions only returns unaligned buffer, so that data of some members are always wrong. /Zp is out of choice, since it breaks the other parts of the program. I know #pragma pack modifies the alignment of the following struct, but I would like to avoid copying the structs into my code, for the definitions in the library might change in the future. Sample code: test.h: struct am_aligned { BYTE data1[10]; ULONG data2; }; test.cpp: #include "test.h" // typedef alignment(1) struct am_aligned am_unaligned; int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) { char buffer[20] = {}; for (int i = 0; i < sizeof(unaligned_struct); i++) { buffer[i] = i; } am_aligned instance = *(am_aligned*) buffer; return 0; } Consider am_aligned is defined in the library header file. am_unaligned is my custom declaration, and only effective in test.cpp. The commented line does not work of course. instance.data2 is 0x0f0e0d0c, while 0x0d0c0b0a is desired. Thanks for help!

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  • Get Instance ID of an Object in PHP

    - by Alix Axel
    I've learn a while ago on StackOverflow that we can get the "instance ID" of any resource, for instance: var_dump(intval(curl_init())); // int(2) var_dump(intval(finfo_open())); // int(3) var_dump(intval(curl_init())); // int(4) var_dump(intval(finfo_open())); // int(5) var_dump(intval(curl_init())); // int(6) I need something similar but applied to classes: var_dump(intval(new stdClass())); // int(1) var_dump(intval(new stdClass())); // int(1) var_dump(intval(new stdClass())); // int(1) var_dump(intval(new stdClass())); // int(1) var_dump(intval(new stdClass())); // int(1) I'm using stdClass just has an example here, but as you can see, it's not the output I was hoping for. I just did some more testing and I found that var_dump() can see the instance ID of an object: var_dump($a = new stdClass()); // object(stdClass)#1 (0) { } var_dump($b = new stdClass()); // object(stdClass)#2 (0) { } var_dump($c = new stdClass()); // object(stdClass)#3 (0) { } The same happens with resources of course: var_dump(curl_init()); // resource(2) of type (curl) var_dump(curl_init()); // resource(3) of type (curl) var_dump(curl_init()); // resource(4) of type (curl) Is there any way to achieve the same effect in PHP?

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  • Working with EnumSet class in GWT

    - by zenmonkey
    I am having trouble using EnumSet on the client side. I get this runtime error message: java.util.EnumSet.EnumSetImpl is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. Is this is a known issue? Here is what I am doing (basically a hello world app) Service: String echo (EnumSet<Names> name) throws IllegalArgumentException; Client: echoServ.echo (EnumSet.of(Names.JOHN), new AsyncCallback<String>() { ....... }); Shared enum class enum Names { JOHN, NUMAN, OBAMA }

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  • postgreSQL - pg_class question

    - by Sachin Chourasiya
    PostgreSQL stores statistics about tables in the system table called pg_class. The query planner accesses this table for every query. These statistics may only be updated using the analyze command. If the analyze command is not run often, the statistics in this table may not be accurate and the query planner may make poor decisions which can degrade system performance. Another strategy is for the query planner to generate these statistics for each query (including selects, inserts, updates, and deletes). This approach would allow the query planner to have the most up-to-date statistics possible. Why postgres always rely on pg_class instead?

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  • Definitive method for sizing font in css

    - by David
    Hi there, I would like to know some opinions from experienced developers on what they think the definitive way to size fonts (in a base sense). I know that working with ems is considered best but im referring to the best way to set the base font size. There is the technique of setting font to 10px using 62.5 method but i think ie has an issue with rounding which throws this out slightly (perhaps not) YUI framework uses body { font:13px/1.231 arial,helvetica,clean,sans-serif; /* for IE6/7 */ *font-size:small; /* for IE Quirks Mode */ *font:x-small; } which really confuses me! Tripoli uses html { font-size:125%; } body { font-size:50%; } a list apart suggest something along the lines of : body { font-size: 16px; *font-size: 100%; } So which is the best either out of these methods or any alternatives. The best being the easiest to work with and the most reliable cross browser.

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  • C# WPF Apllication class

    - by hans
    my applicationen consists of App.cs/App.xaml and some other files. Everything is compiled to an exe file. However, I want a 2. application, which should reference the first one. In this Application is a class derived from App. But when I call the the Run() function I get an very stragne error in a xaml code of the first application, saying that some image files could not be loaded. I had a similar architecture when i was using Windows Forms and it worked fine.

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  • Call a function from another Class - Obj C

    - by AndrewDK
    I'm trying to figure out how I can call a function from another one of my classes. I'm using a RootViewController to setup one of my views as lets say AnotherViewController So in my AnotherViewController im going to add in on the .h file @class RootViewController And in the .m file im going to import the View #import "RootViewController.h" I have a function called: -(void)toggleView { //do something } And then in my AnotherViewController I have a button assigned out as: -(void)buttonAction { //} In the buttonAction I would like to be able to call the function toggleView in my RootViewController. Can someone clarify on how I do this. I've tried adding this is my buttonAction: RootViewController * returnRootObject = [[RootViewController alloc] init]; [returnRootObject toggleView]; But I dont think that's right. Thanks in advanced.

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  • postgres SQL - pg_class question

    - by Sachin Chourasiya
    PostgreSQL stores statistics about tables in the system table called pg_class. The query planner accesses this table for every query. These statistics may only be updated using the analyze command. If the analyze command is not run often, the statistics in this table may not be accurate and the query planner may make poor decisions which can degrade system performance. Another strategy is for the query planner to generate these statistics for each query (including selects, inserts, updates, and deletes). This approach would allow the query planner to have the most up-to-date statistics possible. Why postgres always rely on pg_class instead?

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  • Method of getting text on a windows form ( unmanaged C++ project )

    - by Donovan
    I'm in the process of learning C++. I've created a boilerplate Win32 app within VC++ 2008. I've studied through the code and am ready do do a bit of experimenting. I thought it would be cool to print all the windows messages received in the message loop to the form created via the boilerplate code. I for the life of me, can't figure out the method of getting text onto that form. I can't seem to identify and named object that I can use to reference that damn form. The best I can figure is I need to use the handle to reference the form somehow. Still, even if I did know how to reference the form, I'm not sure I know how I would create a label to display the text. Anyway, if someone could just point out what methodology I need to learn to make this happen it would be much appreciated. Thanks, Donovan

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  • Is this class + constructor definition pattern overly redundant?

    - by Protector one
    I often come across a pattern similar to this: class Person { public string firstName, lastName; public Person(string firstName, string lastName) { this.firstName = firstName; this.lastName = lastName; } } This feels overly redundant (I imagine typing "firstName" once, instead of thrice could be enough…), but I can't think of a proper alternative. Any ideas? Maybe I just don't know about a certain design pattern I should be using here? Edit - I think I need to elaborate a little. I'm not asking how to make the example code "better", but rather, "shorter". In its current state, all member names appear 3 times (declaration, initialization, constructor arguments), and it feels rather redundant. So I'm wondering if there is a pattern (or semantic sugar) to get (roughly) the same behavior, but with less bloat. I apologize for being unclear initially.

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  • Right method to build a online whiteboard - JAVA

    - by Nikhar Sharma
    I am building a whiteboard, which would have a server(teacher) and clients(students). Teacher would draw something on his side, which will be shown exactly same to the students. I want to know which component i should use to do the drawing? i am currently drawing on JPanel . I want the screen of Server gets copied on the clients, so for that what could be the right method to do this? option1: i save the JPanel as image, and send thru socket, and loads it on the screen of client, also it always saves the background image only, not what the user has drawn onto it. OR option2: both server and client JPanel dimensions are same, so i just send the new coordinates drawn everytime thru socket, with some protocol to understand whether it is rubber or pencil.. Any help would be appreciated.

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  • Displaying the error message from web service in jquery validation custom method

    - by Mrt
    Hello, I'm adding a custom method to jquery validation that calls a webservice, but the web service returns more then just a boolean. Is it possible to show the error based on return call of the web service. e.g. say I want an email address to be valid & not in use, so my web service checks this an returns 0 - ok, 1 - not valid, 2 - in use. How can I get jquery to show to correct error message based in the response ?

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  • how to cout a vector of structs (that's a class member, using extraction operator)

    - by Julz
    hi, i'm trying to simply cout the elements of a vector using an overloaded extraction operator. the vector contians Point, which is just a struct containing two doubles. the vector is a private member of a class called Polygon, so heres my Point.h #ifndef POINT_H #define POINT_H #include <iostream> #include <string> #include <sstream> struct Point { double x; double y; //constructor Point() { x = 0.0; y = 0.0; } friend std::istream& operator >>(std::istream& stream, Point &p) { stream >> std::ws; stream >> p.x; stream >> p.y; return stream; } friend std::ostream& operator << (std::ostream& stream, Point &p) { stream << p.x << p.y; return stream; } }; #endif my Polygon.h #ifndef POLYGON_H #define POLYGON_H #include "Segment.h" #include <vector> class Polygon { //insertion operator needs work friend std::istream & operator >> (std::istream &inStream, Polygon &vertStr); // extraction operator friend std::ostream & operator << (std::ostream &outStream, const Polygon &vertStr); public: //Constructor Polygon(const std::vector<Point> &theVerts); //Default Constructor Polygon(); //Copy Constructor Polygon(const Polygon &polyCopy); //Accessor/Modifier methods inline std::vector<Point> getVector() const {return vertices;} //Return number of Vector elements inline int sizeOfVect() const {return vertices.size();} //add Point elements to vector inline void setVertices(const Point &theVerts){vertices.push_back (theVerts);} private: std::vector<Point> vertices; }; and Polygon.cc using namespace std; #include "Polygon.h" // Constructor Polygon::Polygon(const vector<Point> &theVerts) { vertices = theVerts; } //Default Constructor Polygon::Polygon(){} istream & operator >> (istream &inStream, Polygon::Polygon &vertStr) { inStream >> ws; inStream >> vertStr; return inStream; } // extraction operator ostream & operator << (ostream &outStream, const Polygon::Polygon &vertStr) { outStream << vertStr.vertices << endl; return outStream; } i figure my Point insertion/extraction is right, i can insert and cout using it and i figure i should be able to just...... cout << myPoly[i] << endl; in my driver? (in a loop) or even... cout << myPoly[0] << endl; without a loop? i've tried all sorts of myPoly.at[i]; myPoly.vertices[i]; etc etc also tried all veriations in my extraction function outStream << vertStr.vertices[i] << endl; within loops, etc etc. when i just create a... vector<Point> myVect; in my driver i can just... cout << myVect.at(i) << endl; no problems. tried to find an answer for days, really lost and not through lack of trying!!! thanks in advance for any help. please excuse my lack of comments and formatting also there's bits and pieces missing but i really just need an answer to this problem thanks again

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  • WPF style problem with custom control and textbox-derived class

    - by Martin
    I had the following situation: main application has app.xaml, which sets the style for TextBox controls a custom control is implemented in a separate DLL, and uses several TextBox controls The main application's TextBox style is applied to the custom control's TextBox controls. Cool! My problem comes in because I need to use a class derived from TextBox in the custom control. Now the main app's TextBox style is no longer applied. Can the custom control DLL have something like "app.xaml" where I can set the style for all my derived TextBox controls? Or can the main application somehow set the style for all TextBox-derived classes? Thanks!

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  • Stored procedure call in method with OperationBehavior attribute: problems with transactions

    - by Gerrie Schenck
    I'm using ADO.Net's ExecuteNonQuery to call a stored procedure, works like a charm stand-alone but when implementing it where it should be called I'm running into problems concerning transactions. For example System.Data.SqlClient.SqlException: Transaction count after EXECUTE indicates a mismatching number of BEGIN and COMMIT statements. Previous count = 1, current count = 0. and also a timeout right after that. I've just found out the method which calls the stored procedure is marked with the following WCF attribute: [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)] How will this influence the call my stored procedure? How can I tell .Net to execute the stored procedure outside this transaction? The stored procedure contains insert statements and also a transaction, but removing them doesn't change the behavior...

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  • What is the purpose of abstract classes?

    - by SpikETidE
    I am trying to learn OOP in PHP, and I have some confusion about interfaces and abstract classes. They both contain no implementations, only definitions, and should be implemented through their sub-classes. What part of abstract classes clearly distinguishes them from interfaces? Also, due to their apparent similarities, based on what reasons should I decide to use one over the other?

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  • Referring to a non-final variable data inside an inner class

    - by shoaibmohammed
    Im doing a program in GWT. Here is the snippet where Im having problem private String[] populateRSSData() { 1==>> String[] data = null; try { new RequestBuilder(RequestBuilder.GET, "../database.php?action=populaterss").sendRequest(null, new RequestCallback() { @Override public void onResponseReceived(Request request, Response response) { 2==>> data=response.getText().split("~"); } @Override public void onError(Request request, Throwable exception) { Window.alert(exception.getMessage()); } }); } catch (RequestException e) { Window.alert(e.getMessage()); } return data; } Now the problem arises that I get an error that the variable 1==>> data should be declared final. But if I declare it as final then i cannot store the datas in 2==>> The error i get Cannot refer to a non-final variable data inside an inner class defined in a different method RSS_Manager.java Please suggest

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  • swing: event listener support class

    - by Jason S
    Is there any preexisting class that helps support add/remove EventListener operations? (kind of like PropertyChangeSupport) I'm trying to partition my code into a model and view in Java. I have some data that arrives erratically, and would like the model to support some kind of EventListener so that a view can subscribe to changes in the model. The data is numerous + complicated enough that I don't want to have to do the whole fine-grained Javabeans property change support; rather I would just like to allow notification that the model has changed in a coarse way. how can I best do this?

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  • Incorrect emacs indentation in a C++ class with DLL export specification

    - by Michael Daum
    I often write classes with a DLL export/import specification, but this seems to confuse emacs' syntax parser. I end up with something like: class myDllSpec Foo { public: Foo( void ); }; Notice that the "public:" access spec is indented incorrectly, as well as everything that follows it. When I ask emacs to describe the syntax at the beginning of the line containing public, I get a return of: ((label 352)) If I remove the myDllSpec, the indentation is correct, and emacs tells me that the syntax there is: ((inclass 352) (access-label 352)) Which seems correct and reasonable. So I conclude that the syntax parser is not able to handle the DLL export spec, and that this is what's causing my indentation trouble. Unfortunately, I don't know how to teach the parser about my labels. Seems that this is pretty common practice, so I'm hoping there's a way around it.

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