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• Stuck on an ASP.NET/WCF WSDL Parsing Error

  - by Vaccano

  I have a WCF Web Service that my ASP.NET app uses. It has been working fine for quite some time. I just added in a Dev Express Grid (and the Dev Express DLLs) and a new page that uses them and now I am getting parsing errors on the WSDL. But the weird part is that it works fine on my machine but fails on the web server machine. (Both are connecting to the same web services WSDL.) Here is the error message I am getting: Server Error in '/MyWebAppWebDev' Application. -------------------------------------------------------------------------------- Parser Error Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. Parser Error Message: Reference.svcmap: Failed to generate code for the service reference 'MyWebAppService'. Cannot import wsdl:portType Detail: An exception was thrown while running a WSDL import extension: System.ServiceModel.Description.DataContractSerializerMessageContractImporter Error: Referenced type 'WebClientApp.MyWebAppService.ReferenceUpdatesDataContract, WebClientApp, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' with data contract name 'ReferenceUpdatesDataContract' in namespace 'http://schemas.datacontract.org/2004/07/MyWebAppServiceLibrary.DataContracts' cannot be used since it does not match imported DataContract. Need to exclude this type from referenced types. XPath to Error Source: //wsdl:definitions[@targetNamespace='http://tempuri.org/']/wsdl:portType[@name='IMyWebAppReferenceDataServiceLib'] Cannot import wsdl:binding Detail: There was an error importing a wsdl:portType that the wsdl:binding is dependent on. XPath to wsdl:portType: //wsdl:definitions[@targetNamespace='http://tempuri.org/']/wsdl:portType[@name='IMyWebAppReferenceDataServiceLib'] XPath to Error Source: //wsdl:definitions[@targetNamespace='http://tempuri.org/']/wsdl:binding[@name='MyWebAppServicesDefaultEndpoint'] Cannot import wsdl:port Detail: There was an error importing a wsdl:binding that the wsdl:port is dependent on. XPath to wsdl:binding: //wsdl:definitions[@targetNamespace='http://tempuri.org/']/wsdl:binding[@name='MyWebAppServicesDefaultEndpoint'] XPath to Error Source: //wsdl:definitions[@targetNamespace='http://tempuri.org/']/wsdl:service[@name='MyWebAppReferenceDataServiceLib']/wsdl:port[@name='MyWebAppServicesDefaultEndpoint'] Source Error: [No relevant source lines] Source File: /MyWebAppWebDev/App_WebReferences/MyWebAppService/ Line: 1 I am completely stumped on this. I have checked my web.config endpoint address and it is spot on (and notably is not in the error message above). Any ideas would be welcomed. Things I have tried: Giving permissions to C:\Windows\temp to my Website user name Giving permissions to C:\Windows\temp to my App pool user name Checking to see that none of my data contracts are generic and have IsReference=true in them.

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• DSP - Filtering in the frequency domain via FFT

  - by Trap

  I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. Whenever I modify the amplitudes of the frequency bins before calling the iFFT the resulting signal contains some clicks and pops, especially when low frequencies are present in the signal (like drums or basses). However, this does not happen if I attenuate all the bins by the same factor. Let me put an example of the output buffer of a 4-sample FFT: // Bin 0 (DC) FFTOut[0] = 0.0000610351563 FFTOut[1] = 0.0 // Bin 1 FFTOut[2] = 0.000331878662 FFTOut[3] = 0.000629425049 // Bin 2 FFTOut[4] = -0.0000381469727 FFTOut[5] = 0.0 // Bin 3, this is the first and only negative frequency bin. FFTOut[6] = 0.000331878662 FFTOut[7] = -0.000629425049 The output is composed of pairs of floats, each representing the real and imaginay parts of a single bin. So, bin 0 (array indexes 0, 1) would represent the real and imaginary parts of the DC frequency. As you can see, bins 1 and 3 both have the same values, (except for the sign of the Im part), so I guess bin 3 is the first negative frequency, and finally indexes (4, 5) would be the last positive frequency bin. Then to attenuate the frequency bin 1 this is what I do: // Attenuate the 'positive' bin FFTOut[2] *= 0.5; FFTOut[3] *= 0.5; // Attenuate its corresponding negative bin. FFTOut[6] *= 0.5; FFTOut[7] *= 0.5; For the actual tests I'm using a 1024-length FFT and I always provide all the samples so no 0-padding is needed. // Attenuate var halfSize = fftWindowLength / 2; float leftFreq = 0f; float rightFreq = 22050f; for( var c = 1; c < halfSize; c++ ) { var freq = c * (44100d / halfSize); // Calc. positive and negative frequency indexes. var k = c * 2; var nk = (fftWindowLength - c) * 2; // This kind of attenuation corresponds to a high-pass filter. // The attenuation at the transition band is linearly applied, could // this be the cause of the distortion of low frequencies? var attn = (freq < leftFreq) ? 0 : (freq < rightFreq) ? ((freq - leftFreq) / (rightFreq - leftFreq)) : 1; // Attenuate positive and negative bins. mFFTOut[ k ] *= (float)attn; mFFTOut[ k + 1 ] *= (float)attn; mFFTOut[ nk ] *= (float)attn; mFFTOut[ nk + 1 ] *= (float)attn; } Obviously I'm doing something wrong but can't figure out what. I don't want to use the FFT output as a means to generate a set of FIR coefficients since I'm trying to implement a very basic dynamic equalizer. What's the correct way to filter in the frequency domain? what I'm missing? Thanks in advance.

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• Looking for Fiddler2 help. connection to gateway refused? Just got rid of a virus

  - by John Mackey

  I use Fiddler2 for facebook game items, and it's been a great success. I accessed a website to download some dat files I needed. I think it was eshare, ziddu or megaupload, one of those. Anyway, even before the rar file had downloaded, I got this weird green shield in the bottom right hand corner of my computer. It said a Trojan was trying to access my computer, or something to that extent. It prompted me to click the shield to begin anti-virus scanning. It turns out this rogue program is called Antivirus System Pro and is pretty hard to get rid of. After discovering the rogue program, I tried using Fiddler and got the following error: [Fiddler] Connection to Gateway failed.Exception Text: No connection could be made because the target machine actively refused it 127.0.0.1:5555 I ended up purchasing SpyDoctor + Antivirus, which I'm told is designed specifically for getting rid of these types of programs. Anyway, I did a quick-scan last night with spydoctor and malware bytes. Malware picked up 2 files, and Spydoctor found 4. Most were insignificant, but it did find a worm called Worm.Alcra.F, which was labeled high-priority. I don’t know if that’s the Anti-Virus Pro or not, but SpyDoctor said it got rid of all of those successfully. I tried to run Fiddler again before leaving home, but was still getting the "gateway failed" error. Im using the newest version of firefox. When I initially set up the Fiddler 2.2.8.6, I couldn’t get it to run at first, so I found this faq on the internet that said I needed to go through ToolsOptionsSettings and set up an HTTP Proxy to 127.0.0.1 and my Port to 8888. Once I set that up and downloaded this fiddler helper as a firefox add-on, it worked fine. When I turn on fiddler, it automatically takes my proxy setting from no proxy (default) to the 127.0.0.1 with Port 8888 set up. It worked fine until my computer detected this virus. Anyway, hopefully I've given you sufficient information to offer me your best advice here. Like I said, Spydoctor says the bad stuff is gone, so maybe the rogue program made some type of change in my fiddler that I could just reset or uncheck or something like that? Or will I need to completely remove fiddler and those dat files and rar files I downloaded? Any help would be greatly appreciated. Thanks for your time.

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• ASP.NET MVC 2 AJAX dilemma: Lose Models concept or create unmanageable JavaScript

  - by Slightly Frustrated

  Hi, Ok, let's assume we are working with ASP.NET MVC 2 (latest and greatest preview) and we want to create AJAX user interface with jQuery. So what are our real options here? Option 1 - Pass Json from the Controller to the view, and then the view submits Json back to the controller. This means (in the order given): User opens some View (let's say - /Invoices/January) which has to visualize a list of data (e.g. <IEnumerable<X.Y.Z.Models.Invoice>>) Controller retrieves the Model from the repository (assuming we are using repository pattern). Controller creates a new instance of a class which we will serialize to Json. The reasaon we do this, is because the model may not be serializable (circular reference ftl) Controller populates the soon-to-be-serialized class with data Controller serializes the class to Json and passes it the view. User does some change and submits the 'form' The View submits back Json to the controller The Controller now must 'manually' validate the input, because the Json passed does not bind to a Model See, if our View is communicating to the controller via Json, we lose the Model validation, which IMHO is incredible disadvantage. In this case, forget about data annotations and stuff. Option 2 - Ok, the alternative of the first approach is to pass the Models to the Views, which is the default behavior in the template when you start a new project. We pass a strong typed model to the view The view renders the appropriate html and javascript, sticking to the model property names. This is important! The user submits the form. If we stick to the model names, when we .serialize() the form and submit it to the controller it will map to a model. There is no Json mapping. The submitted form directly binds to a strongly typed model, hence, we can use the model validation. E.g. we keep the business logic where it should be. Problem with this approach is, if we refactor some of the Models (change property names, types, etc), the javascript we wrote would become invalid. We will have to manually refactor the scripting and hope we don't miss something. There is no way you can test it either. Ok, the question is - how to write an AJAX front end, which keeps the business logic validation in the model (e.g. controller passes and receives a Model type), but in the same time doesn't screw up the javascript and html when we refactor the model?

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• Java - strange problem storing text to a String[] and then storing the array to a Vector. Help plea

  - by hatboysam

  OK so for background I've only been using Java for a little more than a week and I am making a basic GUI "Recipe Book" application just to test out some of the techniques I've learned. Currently I'm working on the "Add New Recipe" page that allows the user to make a new recipe by adding ingredients one at a time. The ingredients have 3 attributes: Name, amount, and unit (like cups, oz, etc) that come from two text fields and a combo box respectively. The 3 values are stores as strings to a String array that represents the ingredient, then the arrays are stored in a vector that holds all of the ingredients for one recipe. When an ingredient is added, the user first types in the 3 necessary values into empty boxes/combo box dropdown and then clicks "Add Ingredient". Here is my code for when the button is clicked: public void actionPerformed(ActionEvent event) { Object source = event.getSource(); if (source == addIngredientButton) { //make sure 3 ingredient fields are not blank if (!ingredientNameField.getText().equals("") && !ingredientAmountField.getText().equals("") && !ingredientUnitDropdown.getSelectedItem().equals("")) { tempIngredientsArray[0] = ingredientNameField.getText(); //set ingredient name to first position in array tempIngredientsArray[1] = ingredientAmountField.getText(); //set ingredient amount to second position in array tempIngredientsArray[2] = (String) ingredientUnitDropdown.getSelectedItem(); //set ingredient unit to third position in array int ingredientsVectorSize = tempRecipe.ingredientsVector.size(); tempRecipe.ingredientsVector.add(this.tempIngredientsArray); //why would it matter if this and previous statement were switched for (int k = 0; k < ingredientsVectorSize + 1; k++ ) { liveIngredientsListArea.append("\n" + tempRecipe.makeIngredientSentence(k)); System.out.println(Arrays.toString(tempIngredientsArray)); //shows that tempIngredientsArray gets messed up each time } } Now here's the really strange problem I've been having. The first time the user adds an ingredient everything works fine. The second time, the String[] for that ingredient seems to be duplicated, and the third time it's triplicated. Aka the first time it runs the System.out.println might return "{Sugar, 3, Cups}" and the second time it will return "{Flour, 2, Oz.} {Flour, 2, Oz.}" etc. What's causing this strange problem? All help greatly appreciated, let me know if you need any clarification.

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• passing custom object as parameter to a webmethod of asp.net web service

  - by Jon

  Hi, I have a custom class declared as follows (in vb.net) <Serializable()> _ Public Class NumInfo Public n As String Public f As Integer Public fc As char() Public t As Integer Public tc As char() Private validFlag As Boolean = True Public Sub New() End Sub 'I also have public properties(read/write) for all the public variablesEnd Class In my service.asmx codebehind class I have a webmethod as follows: <WebMethod()> _ <XmlInclude(GetType(NumInfo))> _ Public Function ConvertTo(ByVal info As NumInfo) As String Return mbc(info)'mbc is another function defined in my service.asmx "service" class End Function The problem is that when I start debugging it to test it, the page that I get does not contain any fields where I could input the values for the public fields of numInfo. How do I initialise the class? There is no "Invoke" button either. All I see are soap details as below: ConvertToTestThe test form is only available for methods with primitive types as parameters.SOAP 1.1The following is a sample SOAP 1.1 request and response. The placeholders shown need to be replaced with actual values.POST /Converter/BC.asmx HTTP/1.1Host: localhostContent-Type: text/xml; charset=utf-8Content-Length: lengthSOAPAction: "http://Services/ConvertTo"<?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <ConvertTo xmlns="http://Services/"> <info> <n>string</n> <f>int&lt/f> <fc> <char>char</char> <char>char>/char> </fc>..etc.. What am I doing wrong? For the record I tried replacing char() with string to see if it was the array causing problems but that didn't help either. I'm fairly new to web services. I tried replacing the custom object parameter with a primitive parameter just to check how things worked and it rendered a page with an input field and invoke button. I just can't seem to get it working with custom object. Help!

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• Web Services Primer for a WinForms Developer?

  - by Unicorns

  I've been writing client/server applications with Winforms for about six years now, but I have yet to venture into the web space (neither ASP.NET nor web services). Given the direction that the job market has been heading for some time and the fact that I have a basic curiosity, I'd like to get involved with writing web services, but I don't know where to start. I've read about various options (XML/SOAP vs. JSON, REST vs...well, actually I don't know what it's called, etc.), but I'm not sure what sort of criteria are in play when making the determination to use one or the other. Obviously, I'd like to leverage the tools that I have (Visual Studio, the .NET framework, etc.) without hamstringing myself into only targeting a particular audience (i.e. writing the service in such a way as to make it difficult to consume from a Windows Mobile/Android/iPhone client, for example). For the record, my plan--for now--is to use WCF for my web service development, but I'm open to using another .NET approach if that's advisable. I realize that this question is pretty open-ended so it may get closed, but here are some things I'm wondering: What are some things to consider when choosing the type of web service (REST, etc.) I intend to write? Is it possible (and, if so, feasible) to move from one approach to another? Can web services be written in an event-driven way? As I said I'm a Winforms developer, so I'm used to objects raising events for me to react to. For instance, if I have two clients connected to my service, is there a way for me to "push" information to one of them as a result of an action by the other? If this is possible, is this advisable or am I just not thinking about it correctly? What authentication mechanisms seem to work best for public-facing services? What about if I plan to have different types of OS'es and clients connecting to the service? Is there a generally accepted platform-agnostic approach? In the line of authentication, is this something that I should be doing myself (authenticating an managing sessions, etc.) or is this something should be handled at the framework level and I just define exactly how it should work? If that's the case, how do I tell who the requester has authenticated themselves as? I started writing an authentication mechanism (simple username/password combinations stored in the database and a corresponding session table with a GUID key) within my service and just requiring that key to be passed with every operation (other than logging in, of course), but I want to make sure that I'm not reinventing the wheel here. However, I also don't want to clutter up the server with a bunch of machine user accounts just to use Basic authentication. I'm also under the impression that Digest (and of course Windows) authentication requires a machine (or AD) user account.

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• c#: Design advice. Using DataTable or List<MyObject> for a generic rule checker

  - by Andrew White

  Hi, I have about 100,000 lines of generic data. Columns/Properties of this data are user definable and are of the usual data types (string, int, double, date). There will be about 50 columns/properties. I have 2 needs: To be able to calculate new columns/properties using an expression e.g. Column3 = Column1 * Column2. Ultimately I would like to be able to use external data using a callback, e.g. Column3 = Column1 * GetTemperature The expression is relatively simple, maths operations, sum, count & IF are the only necessary functions. To be able to filter/group the data and perform aggregations e.g. Sum(Data.Column1) Where(Data.Column2 == "blah") As far as I can see I have two options: 1. Using a DataTable. = Point 1 above is achieved by using DataColumn.Expression = Point 2 above is acheived by using DataTable.DefaultView.RowFilter & C# code 2. Using a List of generic Objects each with a Dictionary< string, object to store the values. = Point 1 could be achieved by something like NCalc = Point 2 is achieved using LINQ DataTable: Pros: DataColumn.Expression is inbuilt Cons: RowFilter & coding c# is not as "nice" as LINQ, DataColumn.Expression does not support callbacks(?) = workaround could be to get & replace external value when creating the calculated column GenericList: Pros: LINQ syntax, NCalc supports callbacks Cons: Implementing NCalc/generic calc engine Based on the above I would think a GenericList approach would win, but something I have not factored in is the performance which for some reason I think would be better with a datatable. Does anyone have a gut feeling / experience with LINQ vs. DataTable performance? How about NCalc? As I said there are about 100,000 rows of data, with 50 columns, of which maybe 20 are calculated. In total about 50 rules will be run against the data, so in total there will be 5 million row/object scans. Would really appreciate any insights. Thx. ps. Of course using a database + SQL & Views etc. would be the easiest solution, but for various reasons can't be implemented.

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• Help me understand this C code

  - by Benjamin

  INT GetTree (HWND hWnd, HTREEITEM hItem, HKEY *pRoot, TCHAR *pszKey, INT nMax) { TV_ITEM tvi; TCHAR szName[256]; HTREEITEM hParent; HWND hwndTV = GetDlgItem (hWnd, ID_TREEV); memset (&tvi, 0, sizeof (tvi)); hParent = TreeView_GetParent (hwndTV, hItem); if (hParent) { // Get the parent of the parent of the... GetTree (hWnd, hParent, pRoot, pszKey, nMax); // Get the name of the item. tvi.mask = TVIF_TEXT; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); TreeView_GetItem (hwndTV, &tvi); //send the TVM_GETITEM message? lstrcat (pszKey, TEXT ("\\")); lstrcat (pszKey, szName); } else { *pszKey = TEXT ('\0'); szName[0] = TEXT ('\0'); // Get the name of the item. tvi.mask = TVIF_TEXT | TVIF_PARAM; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); if (TreeView_GetItem (hwndTV, &tvi)) //*pRoot = (HTREEITEM)tvi.lParam; //original hItem = (HTREEITEM)tvi.lParam; else { INT rc = GetLastError(); } } return 0; } The block of code that begins with the comment "Get the name of the item" does not make sense to me. If you are getting the listview item why does the code set the parameters of the item being retrieved? If you already had the values there would be no need to retrieve them. Secondly near the comment "original" is the original line of code which will compile with a warning under embedded visual c++ 4.0, but if you copy the exact same code into visual studio 2008 it will not compile. Since I did not write any of this code, and am trying to learn, is it possible the original author made a mistake on this line? The *pRoot should point to HKEY type yet he is casting to an HTREEITEM type which should never work since the data types don't match?

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• jQuery.extend() not giving deep copy of object formed by constructor

  - by two7s_clash

  I'm trying to use this to clone a complicated Object. The object in question has a property that is an array of other Objects, and each of these have properties of different types, mostly primitives, but a couple further Objects and Arrays. For example, an ellipsed version of what I am trying to clone: var asset = new Assets(); function Assets() { this.values = []; this.sectionObj = Section; this.names = getNames; this.titles = getTitles; this.properties = getProperties; ... this.add = addAsset; function AssetObj(assetValues) { this.name = ""; this.title = ""; this.interface = ""; ... this.protected = false; this.standaloneProtected = true; ... this.chaptersFree = []; this.chaptersUnavailable = []; ... this.mediaOptions = { videoWidth: "", videoHeight: "", downloadMedia: true, downloadMediaExt: "zip" ... } this.chaptersAvailable = []; if (typeof assetValues == "undefined") { return; } for (var name in assetValues) { if (typeof assetValues[name] == "undefined") { this[name] = ""; } else { this[name] = assetValues[name]; } } ... function Asset() { return new AssetObj(); } ... function getProperties() { var propertiesArray = new Array(); for (var property in this.values[0]) { propertiesArray.push(property); } return propertiesArray; } ... function addAsset(assetValues) { var newValues; newValues = new AssetObj(assetValues); this.values.push(newValues); } } When I do var copiedAssets = $.extend(true, {}, assets); copiedAssets.values == [], while assets.values == [Object { name="section_intro", more...}, Object { name="select_textbook", more...}, Object { name="quiz", more...}, 11 more...] When I do var copiedAssets = $.extend( {}, assets); all copiedAssets.values.[X].properties are just pointers to the value in assets. What I want is a true deep copy all the way down. What am I missing? Do I need to write a custom extend function? If so, any recommended patterns?

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• Create class instance in assembly from string name

  - by Arcadian

  I'm not sure if this is possible, and I'm quite new to using assemblies in C#.NET. What I would like to do is to create an instance of a class when supplied the string name of that class. Something like this: using MyAssembly; namespace MyNameSpace { Class MyClass { int MyValue1; int MyValue2; public MyClass(string myTypeName) { foreach(Type type in MyAssembly) { if((string)type == myTypeName) { //create a new instance of the type } } AssignInitialValues(//the type created above) } //Here I use an abstract type which the type above inherits from private void AssignInitialValues(AbstractType myClass) { this.value1 = myClass.value1; this.value2 = myClass.value2; } } } Obviously you cannot compare strings to types but it illustrates what I'm trying to do: create a type from a supplied string. Any thoughts? EDIT: After attempting: var myObject = (AbstractType) Activator.CreateInstance(null, myTypeName); AssignInitialValues(myObject); I get a number of errors: Inconsistent accessibility: parameter type 'MyAssembly.AbstractType' is less accessible than method 'MyNameSpace.MyClass.AssignInitialValues(MyAssembly.AstractType)' 'MyAssembly.AstractType' is inaccessible due to it's protection level The type or namespace name 'MyAssembly' could not be found (are you missing a using directive or an assembly reference?) The type or namespace name 'AbstractType' could not be found (are you missing a using directive or an assembly reference?) Not exactly sure why it can't find the assembly; I've added a reference to the assembly and I use a Using Directive for the namespace in the assembly. As for the protection level, it's calling classes (or rather the constructors of classes) which can only be public. Any clues on where the problem is? UPDATE: After looking through several articles on SO I came across this: http://stackoverflow.com/a/1632609/360627 Making the AbstractTypeclass public solved the issue of inconsistent accessibility. The new compiler error is this: Cannot convert type 'System.Runtime.Remoting.ObjectHandle' to 'MyAssembly.AbstractType' The line it references is this one: var myObject = (AbstractType) Activator.CreateInstance(null, myTypeName); Using .Unwrap() get's me past this error and I think it's the right way to do it (uncertain). However, when running the program I then get a TypeLoadException when this code is called. TypeLoadException: Could not load type ‘AbstractType’ from assembly ‘MyNameSpace'... Right away I can spot that the type its looking for is correct but the assembly it's looking in is wrong. Looking up the Activator.CreateInstance(String, String) method revealed that the null as the first argument means that the method will look in the executing assembly. This is contrary to the required behavior as in the original post. I've tried using MyAssembly as the first argument but this produces the error: 'MyAssembly' is a 'namespace' but is used like a 'variable' Any thoughts on how to fix this?

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• C++ vs. C++/CLI: Const qualification of virtual function parameters

  - by James McNellis

  [All of the following was tested using Visual Studio 2008 SP1] In C++, const qualification of parameter types does not affect the type of a function (8.3.5/3: "Any cv-qualifier modifying a parameter type is deleted") So, for example, in the following class hierarchy, Derived::Foo overrides Base::Foo: struct Base { virtual void Foo(const int i) { } }; struct Derived : Base { virtual void Foo(int i) { } }; Consider a similar hierarchy in C++/CLI: ref class Base abstract { public: virtual void Foo(const int) = 0; }; ref class Derived : public Base { public: virtual void Foo(int i) override { } }; If I then create an instance of Derived: int main(array<System::String ^> ^args) { Derived^ d = gcnew Derived; } it compiles without errors or warnings. When I run it, it throws the following exception and then terminates: An unhandled exception of type 'System.TypeLoadException' occurred in ClrVirtualTest.exe Additional information: Method 'Foo' in type 'Derived'...does not have an implementation. That exception seems to indicate that the const qualification of the parameter does affect the type of the function in C++/CLI (or, at least it affects overriding in some way). However, if I comment out the line containing the definition of Derived::Foo, the compiler reports the following error (on the line in main where the instance of Derived is instantiated): error C2259: 'Derived': cannot instantiate abstract class If I add the const qualifier to the parameter of Derived::Foo or remove the const qualifier from the parameter of Base::Foo, it compiles and runs with no errors. I would think that if the const qualification of the parameter affects the type of the function, I should get this error if the const qualification of the parameter in the derived class virtual function does not match the const qualification of the parameter in the base class virtual function. If I change the type of Derived::Foo's parameter from an int to a double, I get the following warning (in addition to the aforementioned error, C2259): warning C4490: 'override': incorrect use of override specifier; 'Derived::Foo' does not match a base ref class method So, my question is, effectively, does the const qualification of function parameters affect the type of the function in C++/CLI? If so, why does this compile and why are there no errors or warnings? If not, why is an exception thrown?

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• What is a good platform for building a game framework targetting both web and native languages?

  - by fuzzyTew

  I would like to develop (or find, if one is already in development) a framework with support for accelerated graphics and sound built on a system flexible enough to compile to the following: native ppc/x86/x86_64/arm binaries or a language which compiles to them javascript actionscript bytecode or a language which compiles to it (actionscript 3, haxe) optionally java I imagine, for example, creating an API where I can open windows and make OpenGL-like calls and the framework maps this in a relatively efficient manner to either WebGL with a canvas object, 3d graphics in Flash, OpenGL ES 2 with EGL, or desktop OpenGL in an X11, Windows, or Cocoa window. I have so far looked into these avenues: Building the game library in haXe Pros: Targets exist for php, javascript, actionscript bytecode, c++ High level, object oriented language Cons: No support for finally{} blocks or destructors, making resource cleanup difficult C++ target does not allow room for producing highly optimized libraries -- the foreign function interface requires all primitive types be boxed in a wrapper object, as if writing bindings for a scripting language; these feel unideal for real-time graphics and audio, especially exporting low-level functions. Doesn't seem quite yet mature Using the C preprocessor to create a translator, writing programs entirely with macros Pros: CPP is widespread and simple to use Cons: This is an arduous task and probably the wrong tool for the job CPP implementations differ widely in support for features (e.g. xcode cpp has no variadic macros despite claiming C99 compliance) There is little-to-no room for optimization in this route Using llvm's support for multiple backends to target c/c++ to web languages Pros: Can code in c/c++ LLVM is a very mature highly optimizing compiler performing e.g. global inlining Targets exist for actionscript (alchemy) and javascript (emscripten) Cons: Actionscript target is closed source, unmaintained, and buggy. Javascript targets do not use features of HTML5 for appropriate optimization (e.g. linear memory with typed arrays) and are immature An LLVM target must convert from low-level bytecode, so high-level constructs are lost and bloated unreadable code is created from translating individual instructions, which may be more difficult for an unprepared JIT to optimize. "jump" instructions cause problems for languages with no "goto" statements. Using libclang to write a translator from C/C++ to web languages Pros: A beautiful parsing library providing easy access to the code structure Can code in C/C++ Has sponsored developer effort from Apple Cons: Incomplete; current feature set targets IDEs. Basic operators are unexposed and must be manually parsed from the returned AST element to be identified. Translating code prior to compilation may forgo optimizations assumed in c/c++ such as inlining. Creating new code generators for clang to translate into web languages Pros: Can code in C/C++ as libclang Cons: There is no API; code structure is unstable A much larger job than using libclang; the innards of clang are complex Building the game library in Common Lisp Pros: Flexible, ancient, well-developed language Extensive introspection should ease writing translators Translators exist for at least javascript Cons: Unfamiliar language No standardized library functions, widely varying implementations Which of these avenues should I pursue? Do you know of any others, or any systems that might be useful? Does a general project like this exist somewhere already? Thank you for any input.

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• Design Technique: How to design a complex system for processing orders, products and units.

  - by Shyam

  Hi, Programming is fun: I learned that by trying out simple challenges, reading up some books and following some tutorials. I am able to grasp the concepts of writing with OO (I do so in Ruby), and write a bit of code myself. What bugs me though is that I feel re-inventing the wheel: I haven't followed an education or found a book (a free one that is) that explains me the why's instead of the how's, and I've learned from the A-team that it is the plan that makes it come together. So, armed with my nuby Ruby skills, I decided I wanted to program a virtual store. I figured out the following: My virtual Store will have: Products and Services Inventories Orders and Shipping Customers Now this isn't complex at all. With the help of some cool tools (CMapTools), I drew out some concepts, but quickly enough (thanks to my inferior experience in designing), my design started to bite me. My very first product-line were virtual "laptops". So, I created a class (Ruby): class Product attr_accessor :name, :price def initialize(name, price) @name = name @price = price end end which can be instantiated by doing (IRb) x = Product.new("Banana Pro", 250) Since I want my virtual customers to be able to purchase more than one product, or various types, I figured out I needed some kind of "Order" mechanism. class Order def initialize(order_no) @order_no = order_no @line_items = [] end def add_product(myproduct) @line_items << myproduct end def show_order() puts @order_no @line_items.each do |x| puts x.name.to_s + "\t" + x.price.to_s end end end that can be instantiated by doing (IRb) z = Order.new(1234) z.add_product(x) z.show_order Splendid, I have now a very simple ordering system that allows me to add products to an order. But, here comes my real question. What if I have three models of my product (economy, business, showoff)? Or have my products be composed out of separate units (bigger screen, nicer keyboard, different OS)? Surely I could make them three separate products, or add complexity to my product class, but I am looking for are best practices to design a flexible product object that can be used in the real world, to facilitate a complex system. My apologies if my grammar and my spelling are with error, as english is not my first language and I took the time to check as far I could understand and translate properly! Thank you for your answers, comments and feedback!

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• How do I solve "Two different CRTLDLLs are loaded" when using packages in C++ Builder 2010?

  - by David M

  Hi, We are trying to split up our monolithic EXE into a combination of an EXE and several packages. So far, we have one package that we're trying to use, and when running the EXE Codeguard shows the following error on startup: CG Error Two different CRTLDLLs are loaded. CG might report false errors (C:\Windows\system32\CC32100MT.DLL) (D:\Projects\Foo\Bar.bpl) OK I read this as two different runtime libraries being loaded - one, the correct one (CC32100MT.dll), one incorrect, which is the package we're trying to use. Continuing to run the program shows odd errors, especially casting between classes or passing a pointer to a class as a parameter in a method that crosses the EXE/DLL boundary. Codeguard itself doesn't show any other errors at all though. How do we solve this? Some more details We've looked at as many things as we (the developer working on this and I) can collectively think of: Each project is built using runtime packages. The EXE host lists Bar in its package list. Each project is set to compile with dynamic RTL. However, changing this does not solve the problem. The package is linked to the EXE via its BPI file, but linking via a LIB makes no difference either. The EXE and BPL are compiled with the same project settings, where the same options exist for both types of project. We think, anyway :) There is only one copy of the BPL and BPI on the system: it's definitely linking to the right one. Examining the EXE and BPL with Depends and TDump show they are both using C:\Windows\system32\CC32100MT.DLL. They should both be using the one RTL. Creating a new project (a plain VCL forms application) and linking to the BPL (via its BPI) works fine. Something in the process of adding all the files and LIBs that make our EXE contain the code it needs to changes this, but we haven't been able to figure out what. The LIBs all either correspond to DLLs we use (flat C interface, usually look as though they were built with MSVC) or are simple projects with lots of related files, compiled to a lib for the purpose of linking into the EXE - these correspond roughly to the areas of the program we want to split to BPLs, by the way. There don't seem to be project options for the LIB projects that would affect RTL linking, unless we've missed them. I have exhaustively hunted through Depends and looked at all RTL and CC32*.dll files the EXE and every single DLL references. All are identical: rtl140.bpl and CC32100MT.DLL. Fully qualified paths show they are the same files, too. Everything should be using the one same run-time library. We're stumped. Absolutely stumped. We've had other problems using BPLs (they seem to be surprisingly tricky things, especially using C++) but have managed to solve them all. This one we've had no luck at all and we'd really appreciate any insights :) We're using C++Builder 2010 (as part of RAD Studio actually, but with little Delphi code apart from components.)

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• Repeating fields in similar database tables

  - by user1738833

  I have been tasked with working on a database that I have never seen before and I'm looking at the DB structure. Some of the central and most heavily queried and joined tables look like virtual duplicates of each other. Here's a massively simplified representation of the situation, with business-sensitive information changed, listing hypothetical table names and fields: TopLevelGroup: PK_TLGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubGroup: PK_SubGroupId, FK_ParentTopLevelGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubSubGroup: PK_SubSUbGroupId, FK_ParentSubGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK I haven't listed the types of the fields as I don't think it's particularly important to the situation. In addition, it's worth saying that rather than four repeated fields as in the example above, I'm looking at 86 repeated fields. For the most part, those fields genuinely do represent "facts" about the primary table entity, so it's not automatically wrong for that reason. In addition, the "groups" represented here have a property inheritance relationship. If DisplaysXOnBill is NULL in the SubSubGroup, it takes the value of DisplaysXOnBillfrom it's parent, the SubGroup, and so-on up to the TopLevelGroup. Further, the requirements will never require that the model extends beyond three levels, so there is no need for flexibility in that area. Is there a design smell from several tables which describe very similar entities having almost identical fields? If so, what might be a better design of the example above? I'm using the phrase "design smell" to indicate a possible problem. Of course, in any given situation, a particular design might well be the best solution. I'm looking for a more general answer - wondering what might be wrong with this design and what might be the better design were that the case. Possibly related, but not primary questions: Is this database schema in a reasonably normal form (e.g. to 3NF), insofar as can be told from the information I've provided. I can't see a problem with the requirements of 2NF and 3NF, except in their inheriting the requirements of 1NF. Is 1NF satisfied though? Are repeating groups allowed in different tables? Is there a best-practice method for implementing the inheritance relationship in a database as I require? The method above feels clunky to me because any query on the SubSubGroup necessarily needs to join onto the SubGroup and the TopLevelGroup tables to collect inherited facts, which can make even trivial joins requiring facts from the SubSubGroup table rather long-winded. There are, of course, political considerations to making a relatively large change like this. For the purpose of this question, I'm happy to ignore that fact in the interests of keeping the answers ring-fenced to the technical problem.

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• XML Schema for a .NET type that inherits and implements

  - by John Ruiz

  Hi, Please consider the following three .NET types: I have an interface, an abstract class, and a concrete class. My question is how to write the XML Schema to include the properties from the interface and from the abstract class. public interface IStartable { bool RequiresKey { get; set; } void Start(object key); } public abstract class Vehicle { uint WheelCount { get; set; } } public class Car : Vehicle, IStartable { public bool RequiresKey { get; set; } public string Make { get; set; } publilc string Model { get; set; } public Car() {} public void Start(object key) { // start car with key } } I don't know how to complete this schema: <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="cars" xmlns="cars" xmlns:c="cars"> <!-- How do I get car to have vehicle's wheelcount AND IStartable's RequiresKey? --> <xs:element name="Car" type="c:Car" /> <xs:complexType name="Car"> <xs:complexContent> <xs:extension base="c:Vehicle"> <xs:group ref=c:CarGroup" /> </xs:extension> </xs:complexContent> </xs:complexType> <xs:group name="CarGroup"> <xs:sequence> <xs:element name="Make" type="xs:token" /> <xs:element name="Model" type="xs:token" /> </xs:sequence> </xs:group> <xs:complexType name="Vehicle"> <xs:sequence> <xs:element name="WheelCount" type="xs:unsignedInt" /> </xs:sequence> </xs:complexType> <xs:complexType name="IStartable"> <xs:sequence> <xs:element name="RequiresKey" type="xs:boolean" /> </xs:sequence> </xs:complexType> </xs:schema>

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• Unique_ptr compiler errors

  - by Godric Seer

  I am designing and entity-component system for a project, and C++ memory management is giving me a few issues. I just want to make sure my design is legitimate. So to start I have an Entity class which stores a vector of Components: class Entity { private: std::vector<std::unique_ptr<Component> > components; public: Entity() { }; void AddComponent(Component* component) { this -> components.push_back(std::unique_ptr<Component>(component)); } ~Entity(); }; Which if I am not mistaken means that when the destructor is called (even the default, compiler created one), the destructor for the Entity, will call ~components, which will call ~std::unique_ptr for each element in the vector, and lead to the destruction of each Component, which is what I want. The component class has virtual methods, but the important part is its constructor: Component::Component(Entity parent) { parent.addComponent(this) // I am not sure if this would work like I expect // Other things here } As long as passing this to the method works, this also does what I want. My confusion is in the factory. What I want to do is something along the lines of: std::shared_ptr<Entity> createEntity() { std::shared_ptr<Entity> entityPtr(new Entity()); new Component(*parent); // Initialize more, and other types of Components return entityPtr; } Now, I believe that this setup will leave the ownership of the Component in the hands of its Parent Entity, which is what I want. First a small question, do I need to pass the entity into the Component constructor by reference or pointer or something? If I understand C++, it would pass by value, which means it gets copied, and the copied entity would die at the end of the constructor. The second, and main question is that code based on this sample will not compile. The complete error is too large to print here, however I think I know somewhat of what is going on. The compiler's error says I can't delete an incomplete type. My Component class has a purely virtual destructor with an implementation: inline Component::~Component() { }; at the end of the header. However since the whole point is that Component is actually an interface. I know from here that a complete type is required for unique_ptr destruction. The question is, how do I work around this? For reference I am using gcc 4.4.6.

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• Composite Views and View Controllers

  - by BillyK

  Hi, I'm somewhat new to Android and am in the process of designing an application with a couple fairly complex views. One of the views is intended to involve a complex view displaying information associated with model objects and segregated into several different views; the navigation of which is meant to be achieved using sliding effects (i.e. sliding one's finger across the screen to traverse from one screen to the next, etc). The view itself will be used to host multiple sets of views for varying types of model objects, but with a general structure that is reused between them all. As a rough example, the view might come up to display information about a person (the model object), displaying several details views: a view for general information, a view displaying a list of hobbies, and a view displaying a list of other individuals associated with their social network. The same general view, when given a model object representing a particular car would give several different views: A general view with details, A view containing photo images for that vehicle, a view representing locations which it could be purchased from, and a view providing a list of related cars. (NOTE: This is not the real data involved, but is representative of the general intent for the view). The subviews will NOT cover the entire screen real-estate and other features within the view should be both visible and able to be interacted with by the user. The idea here is that there is a general view structure that is reusable and which will manage a set of subviews dynamically generated based upon the type of model object handed to the view. I'm trying to determine the appropriate way to leverage the Android framework in order to best achieve this without violating the integrity of the framework. Basically, I'm trying to determine how to componentize this larger view into reusable units (i.e. general view, model-specific sub-view controllers, and individual detail views). To be more specific, I'm trying to determine if this view is best designed as a composite of several custom View classes or a composite of several Activity classes. I've seen several examples of custom composite views, but they typically are used to compose simple views without complex controllers and without attention to the general Activity lifecycle (i.e. storing and retrieving data related to the model objects, as appropriate). On the other hand, the only real example I've seen regarding a view comprised of a composite of Activities is the TabActivity itself, and that isn't customizable in the fashion that would be necessary for this. Does anyone have any suggestions as to the appropriate way to structure my view to achieve the application framework I'm looking for? Views? Activities? Something else? Any guidance would be appreciated. Thanks in advance.

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• NSLinguisticTagger on the contents of an NSTextStorage- crashing bug

  - by Remy Porter

  I'm trying to use an NSLinguisticTagger to monitor the contents of an NSTextStorage and provide some contextual information based on what the user types. To that end, I have an OverlayManager object, which wires up this relationship: -(void) setView:(NSTextView*) view { _view = view; _layout = view.layoutManager; _storage = view.layoutManager.textStorage; //get the TextStorage from the view [_tagger setString:_storage.string]; //pull the string out, this grabs the mutable version [self registerForNotificationsOn:self->_storage]; //subscribe to the willProcessEditing notification } When an edit occurs, I make sure to trap it and notify the tagger (and yes, I know I'm being annoyingly inconsistent with member access, I'm rusty on Obj-C, I'll fix it later): - (void) textStorageWillProcessEditing:(NSNotification*) notification{ if ([self->_storage editedMask] & NSTextStorageEditedCharacters) { NSRange editedRange = [self->_storage editedRange]; NSUInteger delta = [self->_storage changeInLength]; [_tagger stringEditedInRange:editedRange changeInLength:delta]; //should notify the tagger of the changes [self highlightEdits:self]; } } The highlightEdits message delegates the job out to a pool of "Overlay" objects. Each contains a block of code similar to this: [tagger enumerateTagsInRange:range scheme:NSLinguisticTagSchemeLexicalClass options:0 usingBlock:^(NSString *tag, NSRange tokenRange, NSRange sentenceRange, BOOL *stop) { if (tag == PartOfSpeech) { [self applyHighlightToRange:tokenRange onStorage:storage]; } }]; And that's where the problem is- the enumerateTagsInRange method crashes out with a message: 2014-06-04 10:07:19.692 WritersEditor[40191:303] NSMutableRLEArray replaceObjectsInRange:withObject:length:: Out of bounds This problem doesn't occur if I don't link to the mutable copy of the underlying string and instead do a [[_storage string] copy], but obviously I don't want to copy the entire backing store every time I want to do tagging. This all should be happening in the main run loop, so I don't think this is a threading issue. The NSRange I'm enumerating tags on exists both in the NSTextStorage and in the NSLinguisticTagger's view of the string. It's not even the fact that the applyHighlightToRange call adds attributes to the string, because it crashes before even reaching that line. I attempted to build a test case around the problem, but can't replicate it in those situations: - (void) testEdit { NSAttributedString* str = [[NSMutableAttributedString alloc] initWithString:@"Quickly, this is a test."]; text = [[NSTextStorage alloc] initWithAttributedString:str]; NSArray* schemes = [NSLinguisticTagger availableTagSchemesForLanguage:@"en"]; tagger = [[NSLinguisticTagger alloc] initWithTagSchemes:schemes options:0]; [tagger setString:[text string]]; [text beginEditing]; [[text mutableString] appendString:@"T"]; NSRange edited = [text editedRange]; NSUInteger length = [text changeInLength]; [text endEditing]; [tagger stringEditedInRange:edited changeInLength:length]; [tagger enumerateTagsInRange:edited scheme:NSLinguisticTagSchemeLexicalClass options:0 usingBlock:^(NSString *tag, NSRange tokenRange, NSRange sentenceRange, BOOL *stop) { //doesn't matter, this should crash }]; } That code doesn't crash.

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• PInvokeStackImbalance C# call to unmanaged C++ function

  - by user287498

  After switching to VS2010, the managed debug assistant is displaying an error about an unbalanced stack from a call to an unmanaged C++ function from a C# application. The usuals suspects don't seem to be causing the issue. Is there something else I should check? The VS2008 built C++ dll and C# application never had a problem, no weird or mysterious bugs - yeah, I know that doesn't mean much. Here are the things that were checked: The dll name is correct. The entry point name is correct and has been verified with depends.exe - the code has to use the mangled name and it does. The calling convention is correct. The sizes and types all seem to be correct. The character set is correct. There doesn't seem to be any issues after ignoring the error and there isn't an issue when running outside the debugger. C#: [DllImport("Correct.dll", EntryPoint = "SuperSpecialOpenFileFunc", CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, ExactSpelling = true)] public static extern short SuperSpecialOpenFileFunc(ref SuperSpecialStruct stuff); [StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Ansi)] public struct SuperSpecialStruct { public int field1; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)] public string field2; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 20)] public string field3; [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)] public string field4; public ushort field5; public ushort field6; public ushort field7; public short field8; public short field9; public uint field10; public short field11; }; C++: short SuperSpecialOpenFileFunc(SuperSpecialStruct * stuff); struct SuperSpecialStruct { int field1; char field2[256]; char field3[20]; char field4[10]; unsigned short field5; unsigned short field6; unsigned short field7; short field8; short field9; unsigned int field10; short field11; }; Here is the error: Managed Debugging Assistant 'PInvokeStackImbalance' has detected a problem in 'Managed application path'. Additional Information: A call to PInvoke function 'SuperSpecialOpenFileFunc' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

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• C# - Parse HTML source as XML

  - by fonix232

  I would like to read in a dynamic URL what contains a HTML file, and read it like an XML file, based on nodes (HTML tags). Is this somehow possible? I mean, there is this HTML code: <table class="bidders" cellpadding="0" cellspacing="0"> <tr class="bidRow4"> <td>kucik (automata)</td> <td class="right">9 374 Ft</td> <td class="bidders_date">2010-06-10 18:19:52</td> </tr> <tr class="bidRow4"> <td>macszaf (automata)</td> <td class="right">9 373 Ft</td> <td class="bidders_date">2010-06-10 18:19:52</td> </tr> <tr class="bidRow2"> <td>kucik (automata)</td> <td class="right">9 372 Ft</td> <td class="bidders_date">2010-06-10 18:19:42</td> </tr> <tr class="bidRow2"> <td>macszaf (automata)</td> <td class="right">9 371 Ft</td> <td class="bidders_date">2010-06-10 18:19:42</td> </tr> <tr class="bidRow0"> <td>kucik (automata)</td> <td class="right">9 370 Ft</td> <td class="bidders_date">2010-06-10 18:19:32</td> </tr> <tr class="bidRow0"> <td>macszaf (automata)</td> <td class="right">9 369 Ft</td> <td class="bidders_date">2010-06-10 18:19:32</td> </tr> <tr class="bidRow8"> <td>kucik (automata)</td> <td class="right">9 368 Ft</td> <td class="bidders_date">2010-06-10 18:19:22</td> </tr> <tr class="bidRow8"> <td>macszaf (automata)</td> <td class="right">9 367 Ft</td> <td class="bidders_date">2010-06-10 18:19:22</td> </tr> <tr class="bidRow6"> <td>kucik (automata)</td> <td class="right">9 366 Ft</td> <td class="bidders_date">2010-06-10 18:19:12</td> </tr> <tr class="bidRow6"> <td>macszaf (automata)</td> <td class="right">9 365 Ft</td> <td class="bidders_date">2010-06-10 18:19:12</td> </tr> </table> I want to parse this into a ListView (or a Grid) to create rows with the data contained. All tr are different row, and all td in a given td is a column in the given row. And also I want it to be as fast as possible, as it would update itself in 5 seconds. Is there any library for this?

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• How do you prevent IDisposable from spreading to all your classes?

  - by GrahamS

  Start with these simple classes... Let's say I have a simple set of classes like this: class Bus { Driver busDriver = new Driver(); } class Driver { Shoe[] shoes = { new Shoe(), new Shoe() }; } class Shoe { Shoelace lace = new Shoelace(); } class Shoelace { bool tied = false; } A Bus has a Driver, the Driver has two Shoes, each Shoe has a Shoelace. All very silly. Add an IDisposable object to Shoelace Later I decide that some operation on the Shoelace could be multi-threaded, so I add an EventWaitHandle for the threads to communicate with. So Shoelace now looks like this: class Shoelace { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; // ... other stuff .. } Implement IDisposable on Shoelace Buit now FxCop will complain: "Implement IDisposable on 'Shoelace' because it creates members of the following IDisposable types: 'EventWaitHandle'." Okay, I implement IDisposable on Shoelace and my neat little class becomes this horrible mess: class Shoelace : IDisposable { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; private bool disposed = false; public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } ~Shoelace() { Dispose(false); } protected virtual void Dispose(bool disposing) { if (!this.disposed) { if (disposing) { if (waitHandle != null) { waitHandle.Close(); waitHandle = null; } } // No unmanaged resources to release otherwise they'd go here. } disposed = true; } } Or (as pointed out by commenters) since Shoelace itself has no unmanaged resources, I might use the simpler dispose implementation without needing the Dispose(bool) and Destructor: class Shoelace : IDisposable { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; public void Dispose() { if (waitHandle != null) { waitHandle.Close(); waitHandle = null; } GC.SuppressFinalize(this); } } Watch in horror as IDisposable spreads Right that's that fixed. But now FxCop will complain that Shoe creates a Shoelace, so Shoe must be IDisposable too. And Driver creates Shoe so Driver must be IDisposable. and Bus creates Driver so Bus must be IDisposable and so on. Suddenly my small change to Shoelace is causing me a lot of work and my boss is wondering why I need to checkout Bus to make a change to Shoelace. The Question How do you prevent this spread of IDisposable, but still ensure that your unmanaged objects are properly disposed?

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• In Ruby, how does coerce() actually work?

  - by Jian Lin

  It is said that when we have a class Point and knows how to perform point * 3 like the following: class Point def initialize(x,y) @x, @y = x, y end def *(c) Point.new(@x * c, @y * c) end end point = Point.new(1,2) p point p point * 3 Output: #<Point:0x336094 @x=1, @y=2> #<Point:0x335fa4 @x=3, @y=6> but then, 3 * point is not understood: Point can't be coerced into Fixnum (TypeError) So we need to further define an instance method coerce: class Point def coerce(something) [self, something] end end p 3 * point Output: #<Point:0x3c45a88 @x=3, @y=6> So it is said that 3 * point is the same as 3.*(point) that is, the instance method * takes an argument point and invoke on the object 3. Now, since this method * doesn't know how to multiply a point, so point.coerce(3) will be called, and get back an array: [point, 3] and then * is once again applied to it, is that true? point * 3 which is the same as point.*(3) and now, this is understood and we now have a new Point object, as performed by the instance method * of the Point class. The question is: 1) who invokes point.coerce(3) ? Is it Ruby automatically, or is it some code inside of * method of Fixnum by catching an exception? Or is it by case statement that when it doesn't know one of the known types, then call coerce? 2) Does coerce always need to return an array of 2 elements? Can it be no array? Or can it be an array of 3 elements? 3) And is the rule that, the original operator (or method) * will then be invoked on element 0, with the argument of element 1? (element 0 and element 1 are the two elements in that array returned by coerce) Who does it? Is it done by Ruby or is it done by code in Fixnum? If it is done by code in Fixnum, then it is a "convention" that everybody follows when doing a coerce? So could it be the code in * of Fixnum do something like this: if (something.typeof? ...) else if ... # other type else if ... # other type else # if it is not a type I know array = something.coerce(self) return array[0].*(array[1]) end

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• Problem with GwtUpload on GAE

  - by weesilmania

  I'm using GwtUpload to upload images on GAE. The problem is that the images seem to get much bigger when I move them into a blob. I've noticed the same for simple text fields and in that case I've realised that some weirdo characters are being appended to the end of the field values (encoding right?). Can anyone help? public class ImageUploadServlet extends AppEngineUploadAction { /** * Maintain a list with received files and their content types */ Hashtable<String, File> receivedFiles = new Hashtable<String, File>(); Hashtable<String, String> receivedContentTypes = new Hashtable<String, String>(); private Objectify objfy; public ImageUploadServlet() { ObjectifyService.register(Thumbnail.class); objfy = ObjectifyService.begin(); System.out.println("ImageUploadServlet init"); } /** * Override executeAction to save the received files in a custom place and * delete this items from session. */ @Override public String executeAction(HttpServletRequest request, List<FileItem> sessionFiles) throws UploadActionException { Thumbnail t = new Thumbnail(); for (FileItem item : sessionFiles) { //CacheableFileItem item = (CacheableFileItem)fItem; if (false == item.isFormField()) { System.out.println("the name 1st:" + item.getFieldName()); try { // You can also specify the temporary folder InputStream imgStream = item.getInputStream(); Blob imageBlob = new Blob(IOUtils.toByteArray(imgStream)); t.setMainImage(imageBlob); System.out.println("blob: " + t.getMainImage()); } catch (Exception e) { throw new UploadActionException(e.getMessage()); } } else { System.out.println("the name 2nd:" + item.getFieldName()); String name = item.getFieldName(); String value; try { InputStream is = item.getInputStream(); StringWriter writer = new StringWriter(); IOUtils.copy(is, writer,"UTF-8"); value = writer.toString(); writer.close(); System.out.println("parm name: " + name); System.out.println("parm value: " + value + " **" + value.length()); System.out.println(item.getContentType()); if (name.equals("thumb-name")) { t.setName(value); } } catch (IOException e) { // TODO Auto-generated catch block System.out.println("Error"); e.printStackTrace(); } } removeSessionFileItems(request); } objfy.put(t); return null; } As an example the size of the image is 20kb, and the lib has some debugging that confirms that this is the case when it's uploading the file but the blob ends up being over 1 MB. Wes

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