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  • Get derived class type from a base's class static method

    - by Marco Bettiolo
    Hi, i would like to get the type of the derived class from a static method of its base class. How can this be accomplished? Thanks! class BaseClass { static void Ping () { Type t = this.GetType(); // should be DerivedClass, but it is not possible with a static method } } class DerivedClass : BaseClass {} // somewhere in the code DerivedClass.Ping();

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  • Class Design -- Multiple Calls from One Method or One Call from Multiple Methods?

    - by Andrew
    I've been working on some code recently that interfaces with a CMS we use and it's presented me with a question on class design that I think is applicable in a number of situations. Essentially, what I am doing is extracting information from the CMS and transforming this information into objects that I can use programatically for other purposes. This consists of two steps: Retrieve the data from the CMS (we have a DAL that I use, so this is essentially just specifying what data from the CMS I want--no connection logic or anything like that) Map the parsed data to my own [C#] objects There are basically two ways I can approach this: One call from multiple methods public void MainMethodWhereIDoStuff() { IEnumerable<MyObject> myObjects = GetMyObjects(); // Do other stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); List<MyObject> mappedObjects = new List<MyObject>(); // do stuff to map the CmsDataItems to MyObjects return mappedObjects; } private static IEnumerable<CmsDataItem> GetCmsDataItems() { List<CmsDataItem> cmsDataItems = new List<CmsDataItem>(); // do stuff to get the CmsDataItems I want return cmsDataItems; } Multiple calls from one method public void MainMethodWhereIDoStuff() { IEnumerable<CmsDataItem> cmsDataItems = GetCmsDataItems(); IEnumerable<MyObject> myObjects = GetMyObjects(cmsDataItems); // do stuff with myObjects } private static IEnumerable<MyObject> GetMyObjects(IEnumerable<CmsDataItem> itemsToMap) { // ... } private static IEnumerable<CmsDataItem> GetCmsDataItems() { // ... } I am tempted to say that the latter is better than the former, as GetMyObjects does not depend on GetCmsDataItems, and it is explicit in the calling method the steps that are executed to retrieve the objects (I'm concerned that the first approach is kind of an object-oriented version of spaghetti code). On the other hand, the two helper methods are never going to be used outside of the class, so I'm not sure if it really matters whether one depends on the other. Furthermore, I like the fact that in the first approach the objects can be retrieved from one line-- most likely anyone working with the main method doesn't care how the objects are retrieved, they just need to retrieve the objects, and the "daisy chained" helper methods hide the exact steps needed to retrieve them (in practice, I actually have a few more methods but am still able to retrieve the object collection I want in one line). Is one of these methods right and the other wrong? Or is it simply a matter of preference or context dependent?

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  • PHP extend a class method that is called from another class which extends it and calls the method wi

    - by dan.codes
    I am trying to extend a class and override one of its methods. lets call that class A. My class, class B, is overiding a protected method. Class C extends class A and Class D extends class C. Inside of Class D, the method I am trying to overwrite is also extended here and that calls parent::mymethodimoverriding. That method does not exist in class C so it goes to it in class A. That is the method I am overiding in class B and obviously you can't extend A with B and have those changes show up in D since it does not fall in line with the class hierarchy. I might be wrong, so correct me please. so if my class b is called and ran then class D gets called it runs the method in A and overwrites what I had set. I am thinking there must be a way to get this to work, I am just missing something. here is an example, as you can see in class A there is a call to setTitle and it is set to "Example" In my class I set it to "NewExample". My class is getting called before class D so when class D is called it goes back to the parent and sets the title back to "Example" class A{ protected function _thefunction(){ setTitle("Example"); } } class B extends A{ protected function _thefunction(){ My new code here setTitle("NewExample"); } } class C extends A{ nothing that matters in here for what I am doing } class D extends C{ protected function _thefunction(){ parent::_thefunction(); additional code here } }

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  • Abstract class and constructor

    - by Amutha
    As abstract class can be instantiated ,still why constructor is allowed inside abstract class? public abstract class SomeClass { private string _label; public SomeClass(string label) { _label=label; } }

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  • Converting from One Class to another Class using Xml Serialization in C#

    - by nrk
    Hi, In our project we are consuming WCF webservices exposed at Central location as services with basicHttpBinding. In client desktop application we need consume those webservices. I am able to generate proxy class using WSDL.exe. But, I need to convert data/class given by the webservice into my local class, for that now I am xmlserialzing those class/objects given by webservice and deserializing into my local classes as both classes schema matches exactly same. Is there any better way that I can follow? or Do I need to assign each property from one class to another? thanks nRk.

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  • USE case to Class Diagram - How do I?

    - by 01010011
    Hi, I would like your guidance on how to create classes and their relationships (generalization, association, aggregation and composition) accurately from my USE case diagram (please see below). I am trying to create this class diagram so I can use it to create a simple online PHP application that allows the user to register an account, login and logout, and store, search and retrieve data from a MySQL database. Are my classes correct? Or should I create more classes? And if so, what classes are missing? What relationships should I use when connecting the register, login, logout, search_database and add_to_database to the users? I'm new to design patterns and UML class diagrams but from my understanding, the association relationship relates one object with another object; the aggregation relationship is a special kind of association that allows "a part" to belong to more than one "whole" (e.g. a credit card and its PIN - the PIN class can also be used in a debit card class); and a composition relationship is a special form of aggregation that allows each part to belong to only one whole at a time. I feel like I have left out some classes or something because I just can't seem to find the relationships from my understanding of relationships. Any assistance will be really appreciated. Thanks in advance. USE CASE DIAGRAM CLASS DIAGRAM

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  • How to design shape class

    - by Tomek Tarczynski
    I want to design shape class. I need to distinguish several different shapes: -Point -Line -Triangle -Circle -Polygons The main purpose of this class is to calculate distance between two shapes. I've all methods for calculating those distances, but I want to have a single method that can be used, it should looks like this: float Distance(Shape a, Shape b) Simplest way to do it is to put a lot of if statements and then invoke proper method but this is deffinitely not OOP. How to design such class in OOP style?

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  • Python - help on custom wx.Python (pyDev) class

    - by Wallter
    I have been hitting a dead end with this program. I am trying to build a class that will let me control the BIP's of a button when it is in use. so far this is what i have (see following.) It keeps running this weird error TypeError: 'module' object is not callable - I, coming from C++ and C# (for some reason the #include... is so much easier) , have no idea what that means, Google is of no help so... I know I need some real help with sintax and such - anything woudl be helpful. Note: The base code found here was used to create a skeleton for this 'custom button class' Custom Button import wx from wxPython.wx import * class Custom_Button(wx.PyControl): # The BMP's # AM I DOING THIS RIGHT? - I am trying to get empty 'global' # variables within the class Mouse_over_bmp = None #wxEmptyBitmap(1,1,1) # When the mouse is over Norm_bmp = None #wxEmptyBitmap(1,1,1) # The normal BMP Push_bmp = None #wxEmptyBitmap(1,1,1) # The down BMP Pos_bmp = wx.Point(0,0) # The posisition of the button def __init__(self, parent, NORM_BMP, PUSH_BMP, MOUSE_OVER_BMP, pos, size, text="", id=-1, **kwargs): wx.PyControl.__init__(self,parent, id, **kwargs) # The conversions, hereafter, were to solve another but. I don't know if it is # necessary to do this since the source being given to the class (in this case) # is a BMP - is there a better way to prevent an error that i have not # stumbled accost? # Set the BMP's to the ones given in the constructor self.Mouse_over_bmp = wx.Bitmap(wx.Image(MOUSE_OVER_BMP, wx.BITMAP_TYPE_ANY).ConvertToBitmap()) self.Norm_bmp = wx.Bitmap(wx.Image(NORM_BMP, wx.BITMAP_TYPE_ANY).ConvertToBitmap()) self.Push_bmp = wx.Bitmap(wx.Image(PUSH_BMP, wx.BITMAP_TYPE_ANY).ConvertToBitmap()) self.Pos_bmp = self.pos self.Bind(wx.EVT_LEFT_DOWN, self._onMouseDown) self.Bind(wx.EVT_LEFT_UP, self._onMouseUp) self.Bind(wx.EVT_LEAVE_WINDOW, self._onMouseLeave) self.Bind(wx.EVT_ENTER_WINDOW, self._onMouseEnter) self.Bind(wx.EVT_ERASE_BACKGROUND,self._onEraseBackground) self.Bind(wx.EVT_PAINT,self._onPaint) self._mouseIn = self._mouseDown = False def _onMouseEnter(self, event): self._mouseIn = True def _onMouseLeave(self, event): self._mouseIn = False def _onMouseDown(self, event): self._mouseDown = True def _onMouseUp(self, event): self._mouseDown = False self.sendButtonEvent() def sendButtonEvent(self): event = wx.CommandEvent(wx.wxEVT_COMMAND_BUTTON_CLICKED, self.GetId()) event.SetInt(0) event.SetEventObject(self) self.GetEventHandler().ProcessEvent(event) def _onEraseBackground(self,event): # reduce flicker pass def _onPaint(self, event): dc = wx.BufferedPaintDC(self) dc.SetFont(self.GetFont()) dc.SetBackground(wx.Brush(self.GetBackgroundColour())) dc.Clear() dc.DrawBitmap(self.Norm_bmp) # draw whatever you want to draw # draw glossy bitmaps e.g. dc.DrawBitmap if self._mouseIn: # If the Mouse is over the button dc.DrawBitmap(self, self.Mouse_over_bmp, self.Pos_bmp, useMask=False) if self._mouseDown: # If the Mouse clicks the button dc.DrawBitmap(self, self.Push_bmp, self.Pos_bmp, useMask=False) Main.py import wx import Custom_Button from wxPython.wx import * ID_ABOUT = 101 ID_EXIT = 102 class MyFrame(wx.Frame): def __init__(self, parent, ID, title): wxFrame.__init__(self, parent, ID, title, wxDefaultPosition, wxSize(400, 400)) self.CreateStatusBar() self.SetStatusText("Program testing custom button overlays") menu = wxMenu() menu.Append(ID_ABOUT, "&About", "More information about this program") menu.AppendSeparator() menu.Append(ID_EXIT, "E&xit", "Terminate the program") menuBar = wxMenuBar() menuBar.Append(menu, "&File"); self.SetMenuBar(menuBar) self.Button1 = Custom_Button(self, parent, -1, "D:/Documents/Python/Normal.bmp", "D:/Documents/Python/Clicked.bmp", "D:/Documents/Python/Over.bmp", wx.Point(200,200), wx.Size(300,100)) EVT_MENU(self, ID_ABOUT, self.OnAbout) EVT_MENU(self, ID_EXIT, self.TimeToQuit) def OnAbout(self, event): dlg = wxMessageDialog(self, "Testing the functions of custom " "buttons using pyDev and wxPython", "About", wxOK | wxICON_INFORMATION) dlg.ShowModal() dlg.Destroy() def TimeToQuit(self, event): self.Close(true) class MyApp(wx.App): def OnInit(self): frame = MyFrame(NULL, -1, "wxPython | Buttons") frame.Show(true) self.SetTopWindow(frame) return true app = MyApp(0) app.MainLoop() Errors (and traceback) /home/wallter/python/Custom Button overlay/src/Custom_Button.py:8: DeprecationWarning: The wxPython compatibility package is no longer automatically generated or actively maintained. Please switch to the wx package as soon as possible. I have never been able to get this to go away whenever using wxPython any help? from wxPython.wx import * Traceback (most recent call last): File "/home/wallter/python/Custom Button overlay/src/Main.py", line 57, in <module> app = MyApp(0) File "/usr/lib/python2.6/dist-packages/wx-2.8-gtk2-unicode/wx/_core.py", line 7978, in __init__ self._BootstrapApp() File "/usr/lib/python2.6/dist-packages/wx-2.8-gtk2-unicode/wx/_core.py", line 7552, in _BootstrapApp return _core_.PyApp__BootstrapApp(*args, **kwargs) File "/home/wallter/python/Custom Button overlay/src/Main.py", line 52, in OnInit frame = MyFrame(NULL, -1, "wxPython | Buttons") File "/home/wallter/python/Custom Button overlay/src/Main.py", line 32, in __init__ wx.Point(200,200), wx.Size(300,100)) TypeError: 'module' object is not callable I have tried removing the "wx.Point(200,200), wx.Size(300,100))" just to have the error move up to the line above. Have I declared it right? help?

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  • Class Self-Reference

    - by Free Bullets
    I have the following code. The angle function needs some information from the class it was called from. What's the best way to do this? class MyScannedRobotEvent extends robocode.ScannedRobotEvent { public int angle(robocode.Robot myRobot) { return (int) Math.toRadians((myRobot.getHeading() + getBearing()) % 360); } } public class MyRobot extends robocode.Robot { int a = angle(**WHATDOIPUTHERE?**) }

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  • GAE - Getting TypeError requiring class instance be passed to class's own method...

    - by Spencer Leland
    I'm really new to programming... I set up a class to give supporting information for Google's User API user object. I store this info in the datastore using db.model. When I call the okstatus method of my user_info class using this code: elif user_info.okstatus(user): self.response.out.write("user allowed") I get this error: unbound method okstatus() must be called with user_info instance as first argument (got User instance instead) Here is my user_info class. class user_info: def auth_ctrlr(self, user): if self.status(user) == status_allowed: return ("<a href=\"%s\">Sign Out</a>)" % (users.create_login_url("/"))) else: return ("<a href=\"%s\">Sign In or Get an Account</a>)" % (users.create_logout_url("/"))) def status(self, user): match = sub_user.gql(qu_by_user_id, user.user_id) return match.string_status def group(self, user): match = sub_user.gql(qu_by_user_id, user.user_id) grp = group_names.gql(qu_by_user_id, match.groupID) return grp def okstatus(self, user): match = self.status(user) if match == status_allowed: return True My understanding is that the argument "self" inside the method's calling arguments describes it as a child to the class. I've tried everything I can think of and can't find any related info online. Can someone please tell me what I'm doing wrong? Thanks

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  • compiler warning at C++ template base class

    - by eike
    I get a compiler warning, that I don't understand in that context, when I compile the "Child.cpp" from the following code. (Don't wonder: I stripped off my class declarations to the bare minuum, so the content will not make much sense, but you will see the problem quicker). I get the warning with VS2003 and VS2008 on the highest warning level. The code AbstractClass.h : #include <iostream> template<typename T> class AbstractClass { public: virtual void Cancel(); // { std::cout << "Abstract Cancel" << std::endl; }; virtual void Process() = 0; }; //outside definition. if I comment out this and take the inline //definition like above (currently commented out), I don't get //a compiler warning template<typename T> void AbstractClass<T>::Cancel() { std::cout << "Abstract Cancel" << std::endl; } Child.h : #include "AbstractClass.h" class Child : public AbstractClass<int> { public: virtual void Process(); }; Child.cpp : #include "Child.h" #include <iostream> void Child::Process() { std::cout << "Process" << std::endl; } The warning The class "Child" is derived from "AbstractClass". In "AbstractClass" there's the public method "AbstractClass::Cancel()". If I define the method outside of the class body (like in the code you see), I get the compiler warning... AbstractClass.h(7) : warning C4505: 'AbstractClass::Cancel' : unreferenced local function has been removed with [T=int] ...when I compile "Child.cpp". I do not understand this, because this is a public function and the compiler can't know if I later reference this method or not. And, in the end, I reference this method, because I call it in main.cpp and despite this compiler warning, this method works if I compile and link all files and execute the program: //main.cpp #include <iostream> #include "Child.h" int main() { Child child; child.Cancel(); //works, despite the warning } If I do define the Cancel() function as inline (you see it as out commented code in AbstractClass.h), then I don't get the compiler warning. Of course my program works, but I want to understand this warning or is this just a compiler mistake? Furthermore, if do not implement AbsctractClass as a template class (just for a test purpose in this case) I also don't get the compiler warning...?

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  • Rails class << self

    - by xpepermint
    Hey. I would like to understand what "class << self" stands for in the next example. module Utility class Options #:nodoc: class << self def parse(args) end end end end Thx!

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  • State pattern: Why doesn't the context class implement or inherit the State abstract interface/class

    - by Ricket
    I'm reading about the State pattern. I have only just begun, so of course I begin by reading the entire Wikipedia article on it. I noticed that both of the examples in the article have some base abstract class or Java interface for a generic State's methods/functions. Then there are some states which inherit from the base and implement those methods/functions in different ways. Then there's a Context class which has a private member of type State and which, at any time, can be equal to an instance of one of the implementations. That context class also implements the same methods, and passes them onto the current state instance, and then has an additional method to change the state (or depending on design I understand the change of state could be a reaction to one of the implemented methods). Why doesn't this context class specifically "extend" or "implement" the generic State base class/interface?

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  • Do I correctly understand what a class is?

    - by Matt
    I've had trouble finding a clear, concise laymans definition of a class. Usually, they give general ideas without specifically spelling it out, and I'm wondering if I'm understanding this correctly. As I understand it, a class is the set of code that controls an object. For example, in an app that has a button for 'Yes' and a button for 'No', and a text box for output, the code that tells the computer what to do when the user uses the Yes button is one class, the code for hitting No is another class, and an object is the two buttons and what they do together to influence the output box. Am I right, or am I confusing terms here? Thanks

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  • java: can't use constructors in abstract class

    - by ufk
    Hi. I created the following abstract class for job scheduler in red5: package com.demogames.jobs; import com.demogames.demofacebook.MysqlDb; import org.red5.server.api.IClient; import org.red5.server.api.IConnection; import org.red5.server.api.IScope; import org.red5.server.api.scheduling.IScheduledJob; import org.red5.server.api.so.ISharedObject; import org.apache.log4j.Logger; import org.red5.server.api.Red5; /** * * @author ufk */ abstract public class DemoJob implements IScheduledJob { protected IConnection conn; protected IClient client; protected ISharedObject so; protected IScope scope; protected MysqlDb mysqldb; protected static org.apache.log4j.Logger log = Logger .getLogger(DemoJob.class); protected DemoJob (ISharedObject so, MysqlDb mysqldb){ this.conn=Red5.getConnectionLocal(); this.client = conn.getClient(); this.so=so; this.mysqldb=mysqldb; this.scope=conn.getScope(); } protected DemoJob(ISharedObject so) { this.conn=Red5.getConnectionLocal(); this.client=this.conn.getClient(); this.so=so; this.scope=conn.getScope(); } protected DemoJob() { this.conn=Red5.getConnectionLocal(); this.client=this.conn.getClient(); this.scope=conn.getScope(); } } Then i created a simple class that extends the previous one: public class StartChallengeJob extends DemoJob { public void execute(ISchedulingService service) { log.error("test"); } } The problem is that my main application can only see the constructor without any parameters. with means i can do new StartChallengeJob() why doesn't the main application sees all the constructors ? thanks!

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  • ruby/datamapper: Refactor class methods to module

    - by DeSchleib
    Hello, i've the following code and tried the whole day to refactor the class methods to a sperate module to share the functionality with all of my model classes. Code (http://pastie.org/974847): class Merchant include DataMapper::Resource property :id, Serial [...] class << self @allowed_properties = [:id,:vendor_id, :identifier] alias_method :old_get, :get def get *args [...] end def first_or_create_or_update attr_hash [...] end end end I'd like to archive something like: class Merchant include DataMapper::Resource include MyClassFunctions [...] end module MyClassFunctions def get [...] def first_or_create_or_update[...] end => Merchant.allowed_properties = [:id] => Merchant.get( :id=> 1 ) But unfortunately, my ruby skills are to bad. I read a lot of stuff (e.g. here) and now i'm even more confused. I stumbled over the following two points: alias_method will fail, because it will dynamically defined in the DataMapper::Resource module. How to get a class method allowed_properties due including a module? What's the ruby way to go? Many thanks in advance.

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  • Compare Database container and class container

    - by Mohit Deshpande
    I am using a SQL Server database in my current project. I was watching the MVC Storefront videos (specifically the repository pattern) and I noticed that Rob (the creator of MVC Storefront) used a class called Category and Product, instead of a database and I have notice that using LINQ-SQL or ADO.NET, that a class is generated. Is there an advantage to using a class over a database to store information? Or is it the other way around? Or are they even comparable?

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  • OOP - Handling Automated Instances of a Class - PHP

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

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  • Add LINQ Auto-Generated Value Marker [Column(IsDbGenerated=true)] in Buddy Class

    - by Alex
    Hello, is it possible to decorate a field of a LINQ generated class with [Column(IsDbGenerated=true)] using a buddy class (which is linked to the LINQ class via [MetadataType(typeof(BuddyMetadata))]) ? My goal is to be able to clear and repopulate the LINQ ORM designer without having to set the "Auto Generate Value" property manually every time to re-establish the fact that certain columns are autogenerated. Thanks!

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