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• Some basic UML questions

  - by devoured elysium

  What does it mean when you have something as the following picture? Each Customer has none, one or more Orders while each Order has only one Customer? And in relationship to the following one: What does the black diamond mean in this context? How is that black diamond called? Thanks

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• Place a div over an activeX object

  - by Barlow Tucker

  I have a div box that needs to pop up over an ActiveX object, but it seems that an ActiveX object has an infinitely high z-index, even if when I set that index to be low. My div box continues to show up under the ActiveX object. Any ideas?

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• VB.NET: what does the 'friend' modifier do?

  - by Craig Johnston

  What does the 'friend' modifier do in VB.NET? Why is it the default modifier for GUI components in Visual Studio?

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• Compiler doesn't find methods from base class

  - by Paul

  I am having a problem with my virtual methods in a derived class. Here are my (simplified) C++ classes. class Base virtual method accept( MyVisitor1* v ) { /*implementation is here*/ }; virtual method accept( MyVisitor2* v ) { /*implementation is here*/ }; virtual method accept( MyVisitor3* v ) { /*implementation is here*/ }; class DerivedClass virtual method accept( MyVisitor2* v ) { /*implementation is here*/ }; The following use causes VS 2005 to give: "error C2664: 'DerivedClass::accept' : cannot convert parameter 1 from 'Visitor1*' to 'Visitor2 *'". DerivedClass c; MyVisitor1 v1; c.accept(v1); I was expecting the compiler to find and call Base::accept(MyVisitor1) for my DerivedClass as well. Obviously this is not working, but I don't understand why. Any ideas? Thanks, Paul

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• c#3.5 Deserialization error - object reference not set

  - by BBR

  I am trying to deserialize an xml string in c#3.5, the code below does work in c# 4.0. When I try to run in the code in c#3.5 I get an Object reference not set to an instance of an object exception when the code tries in initialize the XmlSerializer. Any help would be appreciated. string xml = "<boolean xmlns=\"http://schemas.microsoft.com/2003/10/serialization/\">false</boolean>"; var xSerializer = new XmlSerializer(typeof(bool), null, null, new XmlRootAttribute("boolean"), "http://schemas.microsoft.com/2003/10/serialization/"); using (var sr = new StringReader(xml)) using (var xr = XmlReader.Create(sr)) { var y = xSerializer.Deserialize(xr); } System.NullReferenceException was unhandled Message="Object reference not set to an instance of an object." Source="System.Xml" StackTrace: at System.Xml.Serialization.XmlSerializer..ctor(Type type, XmlAttributeOverrides overrides, Type[] extraTypes, XmlRootAttribute root, String defaultNamespace, String location, Evidence evidence) at System.Xml.Serialization.XmlSerializer..ctor(Type type, XmlAttributeOverrides overrides, Type[] extraTypes, XmlRootAttribute root, String defaultNamespace) .... at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException:

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• Interface vs Abstract Class (general OO)

  - by Kave

  Hi, I have had recently two telephone interviews where I've been asked about the differences between an Interface and an Abstract class. I have explained every aspect of them I could think of, but it seems they are waiting for me to mention something specific, and I dont know what it is. From my experience I think the following is true, if i am missing a major point please let me know: Interface: Every single Method declared in an Interface will have to be implemented in the subclass. Only Events, Delegates, Properties (C#) and Methods can exist in a Interface. A class can implement multiple Interfaces. Abstract Class Only Abstract methods have to be implemented by the subclass. An Abstract class can have normal methods with implementations. Abstract class can also have class variables beside Events, Delegates, Properties and Methods. A class can only implement one abstract class only due non-existence of Multi-inheritance in C#. 1) After all that the interviewer came up with the question What if you had an Abstract class with only abstract methods, how would that be different from an interface? I didnt know the answer but I think its the inheritance as mentioned above right? 2) An another interviewer asked me what if you had a Public variable inside the interface, how would that be different than in Abstract Class? I insisted you can't have a public variable inside an interface. I didn't know what he wanted to hear but he wasn't satisfied either. Many Thanks for clarification, Kave See Also: When to use an interface instead of an abstract class and vice versa Interfaces vs. Abstract Classes How do you decide between using an Abstract Class and an Interface?

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• Why doesn't Java support generic Throwables?

  - by polygenelubricants

  class Bouncy<T> extends Throwable { } // Error: the generic class Bouncy<T> may not subclass java.lang.Throwable Why doesn't Java support generic Throwables?

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• object.jquery attribute

  - by Esteve Camps

  Hello, what does this code performs? if(object.jquery){ .... } I don't know what jQuery attribute does. I think it checks if 'object' is a valid jQuery object, but I'm not really sure. Thanks in advance. Esteve

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• Dictionary object syntax?

  - by posfan12

  I'm having trouble figuring out the syntax for a JScript .NET dictionary object. I have tried private var myDictionary: Dictionary<string><string>; but the compiler complains that it's missing a semicolon and that the Dictionary object is not declared. I know JScript does have a native dictionary-like object format, but I'm not sure if there are disadvantages to using it instead of the .NET-specific construct. I.e., what if someone wants to extend my script using another .NET language?

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• How to "uninstantiate" an object?

  - by Mark

  I wrote a function in Python: def instantiate(c): if inspect.isclass(c): return c() elif isinstance(c, object): return c else: raise Exception, '%s is not an object or class.' % c Now I want to do the opposite: get the class from an already instantiated object so that I can re-instantiate it with different parameters. How can I do that?

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• how to write a constructor...

  - by Nima

  is that correct to write a constructor like this? class A { A::A(const A& a) { .... } }; if yes, then is it correct to invoke it like this: A* other; ... A* instance = new A(*(other)); if not, what do you suggest? Thanks

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• Grasp Controller, Does it really need a UI to exist?

  - by dbones

  I have a Domain model which can be in multiple states, and if these states go out of a given range it the domain should automatically react. For example I have a Car which is made of multiple things which have measurements the Engine - Rev counter and Temperature the Fuel Tank - capacity Is is plaseable to have a CarStateController, which observses the engine and the tank, and if these states go out of range IE the engine temperature goes above range, turn the engine fan on?? There is no UI, (you could argue it would show a light on the dash board, but for this case it does not) is this a valid use of a GRASP controller pattern? if not what is this CarStateController Called? Or have I completely missed the point and this should be the State Pattern?

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• Python: Getting the attribute name that the created object will be given

  - by cool-RR

  Before I ask this, do note: I want this for debugging purposes. I know that this is going to be some bad black magic, but I want to use it just during debugging so I could identify my objects more easily. It's like this. I have some object from class A that creates a few B instances as attributes: class A(object): def __init__(self) self.vanilla_b = B() self.chocolate_b = B() class B(object): def __init__(self): # ... What I want is that in B.__init__, it will figure out the "vanilla_b" or whatever attribute name it was given, and then put that as the .name attribute to this specific B. Then in debugging when I see some B object floating around, I could know which one it is. Is there any way to do this?

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• C#: what does the 'friend' modifier do?

  - by Craig Johnston

  What does the 'friend' modifier do in C#? Why is it the default modifier for GUI components in Visual Studio?

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• Where do I put javaassist code?

  - by DutrowLLC

  I have an application running on google app engine. I'm using restlets and I have a couple of layers set up including the restlet layer, the model layer, the business layer, and the data layer. I'm attempting to use javaassist to modify some classes, but I'm unsure where to actually put the code. I tried to put the code in the static initialization block: public class Person { String firstName; String getFirstName(){return null;} static{ ClassPool pool = ClassPool.getDefault(); try { CtClass CtPerson = pool.get("Person"); CtMethod CtGetFirstName = CtPerson.getDeclaredMethod("GetFirstName"); CtGetFirstName.setBody("return firstName;"); CtPerson.toClass(); } catch (Exception e) { e.printStackTrace(); } } } ...but that resulted in this error: javassist.CannotCompileException:.....attempted duplicate class definition...". I guess it makes sense that I can't edit the class file in the middle of its generation. I know the code works because I was able to run it correctly by simply putting it in a location that would run when I sent the program a command. (accessed a Restlet resource). The code ran fine if an instance of the class had not already been instantiated, however once I instantiated an instance of the affected class, the javaassist code failed. I assume I need to put this code somewhere that it will only run either: once after the program starts, directly before a class is instantiated for the first time, or even better, during compile time.

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• How to check if two records have a self-referencing relation?

  - by Machine

  Consider the following schema with users and their collegues (friends): Users User: columns: user_id: name: user_id as userId type: integer(8) unsigned: 1 primary: true autoincrement: true first_name: name: first_name as firstName type: string(45) notnull: true last_name: name: last_name as lastName type: string(45) notnull: true email: type: string(45) notnull: true unique: true relations: Collegues: class: User local: invitor foreign: invitee refClass: CollegueStatus equal: true onDelete: CASCADE onUpdate: CASCADE Join table: CollegueStatus: columns: invitor: type: integer(8) unsigned: 1 primary: true invitee: type: integer(8) unsigned: 1 primary: true status: type: enum(8) values: [pending, accepted, denied] default: pending notnull: true Now, let's say I two records, one for the user making a HTTP request (the logged in user), and one record for a user he wants to send a message to. I want to check if these users are collegues. Questions: Does Doctrine have any pre-build functionality to check if two records with with self-relations are related? If not, how would you write a method to check this? Where would you put said method? (In the User-class, UserTable-class etc) I could probably do something like this: public function (User $user1, User $user2) { // Ensure we load collegues if $user1 was fetched with DQL that // doesn't load this relation $collegues = $user1->get('Collegues'); $areCollegues = false; foreach($collegues as $collegue) { if($collegue['userId'] === $user2['userId']) { $areCollegues = true; break; } } return $areCollegues; } But this looks a neither efficient nor pretty. I just feel that it should be solved already for self-referencing relations to be nice to use.

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• getting aspect related information reg

  - by GowthamanSS

  Suppose i have these structure as class ss { public void createfile() { StreamWriter sw= new StreamWriter("d:/test.txt"); } } i need to do aspect where ever i use StreamWriter? as for as consideration i already used the below code as [assembly: MyAspect(AttributeTargetAssembly="mscorlib", AttributeTargetTypes="System.IO.File", AttributeTargetMembers="Create"] for file.create method .. it works fine .. Is there any way to solve this problem ... waiting for your response

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• c# object instantiation

  - by user1112111

  What's the difference between: Object o = new Object(); o.foo(); and new Object().foo(); (assuming I do not need the reference afterwards) ? Are there any reasons for using one instead of the other one (e.g. memory usage) ?

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• Get Excel.Application object from Process or hwnd in .NET

  - by Abiel

  In C# I am trying to get an instance of an Excel.Application object from a Process object. This seems like it should be really simple yet I cannot figure it out and cannot find an example. To repeat, I have a System.Diagnostics.Process object that I know refers to a running Excel instance. I now need to recover a Microsoft.Office.Interop.Excel.Application object that refers to the process so that I can go about manipulating the Excel application from C#. In case it makes it any simpler, I also have the HWND id and window text associated with the active Excel window. Thanks.

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• How to extend this design for a generic converter in java?

  - by Jay

  Here is a small currency converter piece of code: public enum CurrencyType { DOLLAR(1), POUND(1.2), RUPEE(.25); private CurrencyType(double factor) { this.factor = factor; } private double factor; public double getFactor() { return factor; } } public class Currency { public Currency(double value, CurrencyType type) { this.value = value; this.type = type; } private CurrencyType type; private double value; public CurrencyType getCurrencyType() { return type; } public double getCurrencyValue() { return value; } public void setCurrenctyValue(double value){ this.value = value; } } public class CurrencyConversion { public static Currency convert(Currency c1, Currency c2) throws Exception { if (c1 != null && c2 != null) { c2.setCurrenctyValue(c1.getCurrencyValue() * c1.getCurrencyType().getFactor() * c2.getCurrencyType().getFactor()); return c2; } else throw new Exception(); } } I would like to improve this code to make it work for different units of conversion, for example: kgs to pounds, miles to kms, etc etc. Something that looks like this: public class ConversionManager<T extends Convertible> { public T convert(T c1, T c2) { //return null; } } Appreciate your ideas and suggestions.

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• Application Design: Single vs. Multiple Hits to the DB

  - by shyneman

  I'm building a service that performs a set of configured activities based on the type of request that it receives. Each activity involves going to the database and retrieving/updating some kind of information. The logic for each activity can be generalized and re-used across different request types. The activities may need to participate in a transaction for the duration of the servicing the request. One option, I'm considering is having each activity maintain its own access to DAL/database. This fully encapsulates the activity into a stand-alone re-usable piece, but hitting the database multiple times for one request doesn't seem like a viable option. I don't really know how to easily implement the concept of a transaction across the multiple activities here either. The second option is to encapsulate ALL the activities into one big activity and hit the database once. But this does not allow re-use and configuration of these activities for different requests. Does anyone have any suggestions and input about what should be the best way to approach my problem? Thanks for any help.

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• How to use orderby in IQueryable object?

  - by bbbbb

  How to use orderby in IQueryable object?

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• Cannot export a fusionchart with 'Embedding Charts Using <OBJECT>/<EMBED> Tags'

  - by zoom_pat277

  I am trying to export a fusion chart created using 'Embedding Charts Using / Tags'. Export works just perfect with the right click (on the chart) and chose a pdf to export. But I am not able to make this work via javascript. I have a button outside the chart which upon clicking calls the function below function myexport() { var object = getChartFromId('myChartid'); if( object.hasRendered() ) object.exportChart({exportFormat: 'PDF'}); } the object above returned is null and this fails on the next line here is the full prototype <html> <head> <title>My Chart</title> <script type="text/javascript" src="fusionCharts.debug.js"></script> <script type="text/javascript" src="fusionChartsExportComponent.js"></script> <script type="text/javascript"> function ExportMyChart() { var cObject = getChartFromId('Column3D'); if( cObject.hasRendered() ) cObject.exportChart({exportFormat: 'PDF'}); } </script> </head> <body> <object width="400" height="400" id="Column3D" classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://fpdownload.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=8,0,0,0" > <param name="testname" value="Column3D.swf" /> <param name="FlashVars" value="&dataURL=testData.xml&chartWidth=400&chartHeight=300&DOMId=myChart1&registerWithJS=1&debugMode=0"> <param name="quality" value="high" /> <embed src="Column3D.swf" flashVars="&dataURL=testData.xml&chartWidth=400&chartHeight=300&DOMId=myChart1&registerWithJS=1&debugMode=0" width="400" height="300" name="Column3D" quality="high" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" /> </object> <!-- We also create a DIV to contain the FusionCharts client-side exporter component --> <div id="holderDiv" align="center">FusionCharts Export Handler Component</div> <script type="text/javascript"> var myExportComponent = new FusionChartsExportObject("testExporter1", "FCExporter.swf"); //Render the exporter SWF in our DIV fcexpDiv myExportComponent.Render("holderDiv"); </script> <input type="button" value="Export My Chart" onclick="ExportMyChart()" />

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• Comparing all properties of an object using expression trees

  - by stringargs

  Hi, I'm trying to write a simple generator that uses an expression tree to dynamically generate a method that compares all properties of an instance of a type to the properties of another instance of that type. This works fine for most properties, like int an string, but fails for DateTime? (and presumably other nullable value types). The method: static Delegate GenerateComparer(Type type) { var left = Expression.Parameter(type, "left"); var right = Expression.Parameter(type, "right"); Expression result = null; foreach (var p in type.GetProperties()) { var leftProperty = Expression.Property(left, p.Name); var rightProperty = Expression.Property(right, p.Name); var equals = p.PropertyType.GetMethod("Equals", new[] { p.PropertyType }); var callEqualsOnLeft = Expression.Call(leftProperty, equals, rightProperty); result = result != null ? (Expression)Expression.And(result, callEqualsOnLeft) : (Expression)callEqualsOnLeft; } var method = Expression.Lambda(result, left, right).Compile(); return method; } On a DateTime? property it fails with: Expression of type 'System.Nullable`1[System.DateTime]' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)' OK, so it finds an overload of Equals that expects object. So why can't I pass a DateTime? into that, as it's convertible to object? If I look at Nullable<T>, it indeed has an override of Equals(object o). PS: I realize that this isn't a proper generator yet as it can't deal with null values, but I'll get to that :)

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• In what package should a "Settings" class be?

  - by Tom

  I've in the middle of building an application but found myself too easily creating new packages without keeping the project's structure in mind. Now, I'm trying to redo the whole project structure on paper first. I am using a Settings class with public properties, accessed as settings for several other classes around the project. Now, since this Settings class applies for the whole project, I am unsure if it should be packaged and if so, in what kind of package should it exist? Or should it be in the root (the default package) with the main application class? I've been thinking about putting it in my utils package, then again I don't think it really is an utlity. Any strategies on how to decide on such package structure for example for a Settings class?

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