Search Results

Search found 11639 results on 466 pages for 'numerical methods'.

Page 301/466 | < Previous Page | 297 298 299 300 301 302 303 304 305 306 307 308  | Next Page >

• Why is there no parameter contra-variance for overriding?

  - by Oak

  C++ and Java support return-type covariance when overriding methods. Neither, however, support contra-variance in parameter types - instead, it translates to overloading (Java) or hiding (C++). Why is that? It seems to me that there is no harm in allowing that. I can find one reason for it in Java - since it has the "choose-the-most-specific-version" mechanism for overloading anyway - but can't think of any reason for C++. Example (Java): class A { public void f(String s) {...} } class B extends A { public void f(Object o) {...} // Why doesn't this override A.f? }

  Read the article

• Why make anything internal?

  - by c-charp N00b

  I don't really see the point of making methods or classes internal. In my very limited understanding, all it does is make working with your code very difficult for other programmers. Say I write Big_Important_Class for Project A and make said class internal. Then Bob, working on Project B needs to use my class to have project B work with Project A, but since its internal he can't. As of now this is the only thing I have seen internals do, make things really complicated for the guy working on Project B. I know there has to be a good reason to use internals, but I don't see any. Could someone please explain how they can be a good thing?

  Read the article

• can QuickGraph support these requirements? (includes database persistence support)

  - by Greg

  Hi, Would QuickGraph be able to help me out with my requirements below? (a) want to model a graph of nodes and directional relationships between nodes - for example to model web pages/files linked under a URL, or modeling IT infrastructure and dependencies between hardware/software. The library would include methods such as * Node.GetDirectParents() //i.e. there could be more than one direct parent for a node * Node.GetRootParents() //i.e. traverse the tree to the top root parent(s) for the given node * Node.GetDirectChildren() * Node.GetAllChildren() (b) have to persist the data to a database - so it should support SQL Server and ideally SQLite as well. If it does support these requirement then I'd love to hear: any pointers to any parts of QuickGraph to dig into? what is the best concept re it's usage in terms of how to use database persistence - is it a simpler design to assume every search/method works directly on the database, or does QuickGraph support smarts to be able to work in memory and the "save" to database all changes at an appropriate point in time (e.g. like ADO.net does with DataTable etc) Thanks in advance

  Read the article

• Passing objects by reference or not in C#

  - by Piku

  Suppose I have a class like this: public class ThingManager { List<SomeClass> ItemList; public void AddToList (SomeClass Item) { ItemList.Add(Item); } public void ProcessListItems() { // go through list one item at a time, get item from list, // modify item according to class' purpose } } Assume "SomeClass" is a fairly large class containing methods and members that are quite complex (List<s and arrays, for example) and that there may be a large quantity of them, so not copying vast amounts of data around the program is important. Should the "AddToList" method have "ref" in it or not? And why? It's like trying to learn pointers in C all over again ;-) (which is probably why I am getting confused, I'm trying to relate these to pointers. In C it'd be "SomeClass *Item" and a list of "SomeClass *" variables)

  Read the article

• C++ visitor pattern handling templated string types?

  - by Steve the Plant

  I'm trying to use the visitor pattern to serialize the contents of objects. However one snag I'm hitting is when I'm visiting strings. My strings are of a templated type, similar to STL's basic_string. So something like: basic_string<char_type, memory_allocator, other_possible_stuff> \\ many variations possible! Since I can have very many different templated string types, I can't go and add them to my visitor interface. It would be ridiculous. But I can't add templates to my VisitString method because C++ prevents using templates parameters in virtual methods. So what are my options to work around this?

  Read the article

• Hibernate session method to update object

  - by EugeneP

  I need this roadmap of a Hibernate managed object instance. First, I create an instance with initial properties and persist this object in a db. Then session associated with this object is closed. But still, I serialize my object and on the next step deserialize it, invoke some setters, and again, I need to update what changed in a database. What methods of Hibernate session should I use? persist() or save() on the first step and saveOrUpdate() on the second? In fact I see that saveOrUpdate() can be used on each step. What would you recommend?

  Read the article

• Read binary data from a MDB-file running under LAMP

  - by BusterX

  I need to be able to connect to an MDB-file in a LAMP-environment (running on Linux) and ultimately insert converted data into a Mysql db. The data I need to access is stored as a BLOB (Long Binary Data according to Access) in the MDB file. I have not yet been able to actually have a look at the data but I have been told that the BLOB consists of byte strings. Something along the lines of: 0x1c 0x10 0x27 0x00 0x00 I need to parse the byte strings and convert these to a format that is human readable. I do have access to the documentation that explains the various byte strings. So this is really two questions: How do a get access to the MDB file via PHP* (running under LAMP) and read the BLOB (I do not have access to a Windows-platform)? What would be the best way to parse the binary data (in PHP*) once I am able to connect to the MDB-file? *Or are there other methods/languages that are more appropriate?

  Read the article

• Documenting and defining content types for a CMS or similar project

  - by Rimian

  I'm writing up some documentation on a Drupal project and my task is to define the content types and their attributes. The intended audience is project managers and developers. So it could be a high level document that gives an overview of the system. (I think that's how I describe it: high level rather than high detail) At the moment I'm using open office and bullet points but it seems like an amateurish method when I need to describe details that could be useful for a developer (me). Something like UML would describe detail but is probably more complicated than I need right now and could be too technical for others on the team. Are there any universal methods or templates that I can use to describe information in this case?

  Read the article

• How can I upload a file to a Sharepoint Document Library using Silverlight and client web-services?

  - by pclem12

  Most of the solutions I've come across for Sharepoint doc library uploads use the HTTP "PUT" method, but I'm having trouble finding a way to do this in Silverlight because it has restrictions on the HTTP Methods. I visited this http://msdn.microsoft.com/en-us/library/dd920295(VS.95).aspx to see how to allow PUT in my code, but I can't find how that helps you use an HTTP "PUT". I am using client web-services, so that limits some of the Sharepoint functions available. That leaves me with these questions: Can I do an http PUT in Silverlight? If I can't or there is another better way to upload a file, what is it? Thanks

  Read the article

• changing a picker to table view OR having multiple table views on the same view

  - by Brodie4598

  Hello - My iPad app was rejected due to my use of a picker. The picker was used to control a table view. In my view, a picker was displaying a series of items and when one of those items was selected, it used that selection to populate a table with data. (hopefully that makes sense). Now I need to do this without the picker so I need to have the data that was in the picker be represented in a table view. My question, is how do I have multiple tableViews in the same view? I'm guessing I need to have some kind of if statement in the tableview delegate methods, but I'm not quite sure what the if statement needs to be. Or maybe i'm thinking of this the totally wrong way thanks

  Read the article

• Autorelease for CGMutablePathRef?

  - by huggie

  Hi, I am developing for iphone. I want to creating a mutable path via CGPathCreateMutable(), and I want to return it out of the function which creates it. I'm suppose to call a CGPathRelease() when I'm done with it. But since I'm returning it I wish to autorelease it. Since Quartz path is a C code (and doesn't look like an objective C object), is it correct that I cannot call autorelease on it? Edit: For others who stumble upon this question, the below advise is for C functions returning Core foundation objects only. For objective C methods returning Core foundation objects, see http://stackoverflow.com/questions/2901942/ownership-regarding-to-returned-quartz-objects

  Read the article

• C++: Create abstract class with abstract method and override the method in a subclass

  - by Martijn Courteaux

  Hi, How to create in C++ an abstract class with some abstract methods that I want to override in a subclass? How should the .h file look? Is there a .cpp, if so how should it look? In Java it would look like this: abstract class GameObject { public abstract void update(); public abstract void paint(Graphics g); } class Player extends GameObject { @Override public void update() { // ... } @Override public void paint(Graphics g) { // ... } } // In my game loop: for (int i = 0; i < objects.size(); i++) { objects.get(i).update(); } for (int i = 0; i < objects.size(); i++) { objects.get(i).paint(g); } Translating this code to C++ is enough for me.

  Read the article

• Sad logic on types

  - by user2972231

  Code base is littered with code like this: BaseRecord record = // some BaseRecord switch(record.source()) { case FOO: return process((FooRecord)record); case BAR: return process((BarRecord)record); case QUUX: return process((QuuxRecord)record); . . // ~25 more cases . } and then private SomeClass process(BarRecord record) { } private SomeClass process(FooRecord record) { } private SomeClass process(QuuxRecord record) { } It makes me terribly sad. Then, every time a new class is derived from BaseRecord, we have to chase all over our code base updating these case statements and adding new process methods. This kind of logic is repeated everywhere, I think too many to add a method for each and override in the classes. How can I improve this?

  Read the article

• Fast parsing of PHP in C#

  - by Jessica Shea

  Hello there, I've got a requirement for parsing PHP files in C#. We essentially require some of the devs in another country to upload PHP files and once uploaded we need to check the php files and get a list of all the methods and classes/functions etc. I thought of using a regex but I can't workout if a function belongs to a class etc, so I was wondering if theres already something 'out there' that will parse out PHP files and spit out its functions (I'm trying to avoid writing a full blow AST implementation). Does anyone have any idea? I looked at Coco/R but I couldn't find a PHP grammar file. I'm using .NET 2.0 and C#.

  Read the article

• Scala loop returns as Unit and compiler points to "for" syntax?

  - by DeLongey

  Seems like Unit is the theme of my troubles today. I'm porting a JSON deserializer that uses Gson and when it comes to this for loop: def deserialize(json:JsonElement, typeOfT:Type, context:JsonDeserializationContext) = { var eventData = new EventData(null, null) var jsonObject = json.getAsJsonObject for(entry <- jsonObject.entrySet()) { var key = entry.getKey() var element = entry.getValue() element if("previous_attributes".equals(key)) { var previousAttributes = new scala.collection.mutable.HashMap[String, Object]() populateMapFromJSONObject(previousAttributes, element.getAsJsonObject()) eventData.setPreviousAttributes(previousAttributes) eventData } else if ("object".equals(key)) { val `type` = element.getAsJsonObject().get("object").getAsString() var cl = objectMap.get(`type`).asInstanceOf[StripeObject] var `object` = abstractObject.retrieve(cl, key) eventData.setObject(`object`) eventData } } } The compiler spits out the error type mismatch; found : Unit required: com.stripe.EventData and it points to this line here: for(entry <- jsonObject.entrySet()) Questions Confirm that it is indeed the Gson method entrySet() appearing as unit? If not, what part of the code is creating the issue? I've set return types/values for eventData class methods Is there a workaround for the Gson Unit issue? Thanks!

  Read the article

• 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; }

  Read the article

• Resetting Objects vs. Constructing New Objects

  - by byronh

  Is it considered better practice and/or more efficient to create a 'reset' function for a particular object that clears/defaults all the necessary member variables to allow for further operations, or to simply construct a new object from outside? I've seen both methods employed a lot, but I can't decide which one is better. Of course, for classes that represent database connections, you'd have to use a reset method rather than constructing a new one resulting in needless connecting/disconnecting, but I'm talking more in terms of abstraction classes. Can anyone give me some real-world examples of when to use each method? In my particular case I'm thinking mostly in terms of ORM or the Model in MVC. For example, if I would want to retrieve a bunch of database objects for display and modify them in one operation.

  Read the article

• Handling auto-incrementing IDENTITY SQL Server fields with LINQ to SQL in C#

  - by Maxim Z.

  I'm building an ASP.NET MVC site that uses LINQ to SQL to connect to SQL Server, where I have a table that has an IDENTITY bigint primary key column that represents an ID. In one of my code methods, I need to create an object of that table to get its ID, which I will place into another object based on another table (FK-to-PK relationship). At what point is the IDENTITY column value generated and how can I obtain it from my code? Is the right approach to: Create the object that has the IDENTITY column Do an InsertOnSubmit() and SubmitChanges() to submit the object to the database table Get the value of the ID property of the object

  Read the article

• Convert String value format of YYYYMMDDHHMMSS to C# DateTime

  - by SARAVAN

  I have a need to convert a string value in the form "YYYYMMDDHHMMSS" to a DateTime. But not sure on how, may be a DateTime.Tryparse can be used to make this happen. Or is there any other way to do it. I can do this using some string operations to take "YYYYMMDD" alone, convert to a datetime and then add HH, MM, SS separately to that DateTime. But is there any DateTime.TryParse() methods that I can use in one line to convert a "YYYYMMDDHHMMSS" format string value to a DateTime value?

  Read the article

• Designing constructors around type erasure in Java

  - by Internet Friend

  Yesterday, I was designing a Java class which I wanted to be initalized with Lists of various generic types: TheClass(List<String> list) { ... } TheClass(List<OtherType> list) { ... } This will not compile, as the constructors have the same erasure. I just went with factory methods differentiated by their names instead: public static TheClass createWithStrings(List<String> list) public static TheClass createWithOtherTypes(List<OtherType> list) This is less than optimal, as there isn't a single obvious location where all the different options for creating instances are available. I tried to search for better design ideas, but found surprisingly few results. What other patterns exist for designing around this problem?

  Read the article

• Question About Abstract Classes?

  - by IbrarMumtaz

  URL: Link (1) According to this wesbite .. you cannot implement Abstract classes but derive from them. This makes sense and I have read this many times. Like an interface, you cannot implement an instance of an abstract class, however you can implement methods, fields, and properties in the abstract class that can be used by the child class. But on MSDN URL: TextWriter CLass on MSDN TextWriter is an abstract class but it has two constructors defined ... and according to the MS 70-536 book, the following statement is valid: TextWriter tw = new File.CreateText("myFile.Txt") The static file class and it's CreateText method is fine by me as I have studied it on MSDN but can somebody explain this little contradiction I have found? Surely I am not the first? Why is instantaion of base abstract classes possible????

  Read the article

• Implementing 1 to n mapping for ORM c++

  - by karan

  I am writing a project where I need to implement a stripped down version of an ORM solution in C++. I am struck in implementing 1-n relationships for the same. For instance, if the following are the classes: class A { ... } class B { ... std::list<A> _a_list; ... } I have provided load/save methods for loading/saving to the db. Now, if I take the case of B and the following workflow: 1 entry from _a_list is removed 1 entry from _a_list is modified 1 entry is added to _a_list Now, I need to update the db using something like "b.save()". So, what would be the best way to save the changes, i.e, identify the additions, deletions and updates to _a_list.

  Read the article

• Java - How can I edit the size and position of a button using Swing?

  - by mino

  I have the following code but I'd like to structure several buttons of certain sizes. I'm just wondering how to do this as I've Googled it and found several different methods but none seem to work. Any advice? import javax.swing.*; public class GUI { public static void main(String[] args) { JFrame window = new JFrame(); window.setSize(500, 500); window.setTitle("My Application"); JButton button = new JButton("click me"); window.add(button); window.setVisible(true); } }

  Read the article

• PHP Type Hinting: array supported, object NOT?

  - by Marius Burz

  Am I missing something or there really is no support for generic object type hinting in PHP 5.x? I find it really strange that hinting arrays is supported while hinting objects is not, at least not out of the box. I'd like to have something like this: function foo(object $o) Just as we have: function foo(array $o) Example of possible use: methods of an objects collection class. Workaround: using an interface "Object" implemented by all classes or extending all classes from a generic class "Object" and writing something like this: function foo(Object $o) Well, that just ain't cute. Edit: somebody suggested in a deleted post using stdClass. It doesn't work: Catchable fatal error: Argument 1 passed to c::add() must be an instance of stdClass, instance of b given

  Read the article

• Different return value of an overridden class

  - by Samer Afach

  I have a simple but confusing question here. Is it legal to have a different return value type for overridden methods than the abstact ones defined in the base class?? I did that and the compiler didn't complain... could someone please explain? class MyBaseClass { int value; public: virtual int getValue() = 0; }; class MyClass : public MyBaseClass { double value; public: virtual double getValue(); // here!!! return is double, not int }; double MyClass::getValue() { return this->value; } The compiler totally accepted something similar (MSVC und MinGW)... could anyone please exaplain to what extent this is legal?

  Read the article

< Previous Page | 297 298 299 300 301 302 303 304 305 306 307 308  | Next Page >