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• Calling Save on a Configuration obj with a custom sectiongroup of type NameValueSectionHandler

  - by Allen

  I've got aConfiguration object that I can easily read and write settings from and call Save(ConfigurationSaveMode.Minimal, true) on and that typically works just fine. However, I now have a config file that has a custom sectionGroup defined of type System.Configuration.NameValueSectionHandler (I didn't write that part and I can't change it). Now when I call the Save method, it throws a TypeLoadException Message: Type System.Configuration.NameValueSectionHandler does not inherit from System.Configuration.ConfigurationSectionGroup. Callstack: at System.Configuration.TypeUtil.VerifyAssignableType (Type baseType, Type type, Boolean throwOnError) at System.Configuration.TypeUtil.GetConstructorWithReflectionPermission (Type type, Type baseType, Boolean throwOnError) at System.Configuration.MgmtConfigurationRecord.CreateSectionGroupFactory (FactoryRecord factoryRecord) at System.Configuration.MgmtConfigurationRecord.EnsureSectionGroupFactory (FactoryRecord factoryRecord) at System.Configuration.MgmtConfigurationRecord.GetSectionGroup (String configKey) at System.Configuration.ConfigurationSectionGroupCollection.Get (String name) at System.Configuration.ConfigurationSectionGroupCollection. <GetEnumerator>d__0.MoveNext() at System.Configuration.Configuration.ForceGroupsRecursive (ConfigurationSectionGroup group) at System.Configuration.Configuration.SaveAsImpl (String filename, ConfigurationSaveMode saveMode, Boolean forceSaveAll) at System.Configuration.Configuration.Save (ConfigurationSaveMode saveMode, Boolean forceSaveAll) at MyCompany.MyProduct.blah.blah.Save () in C:\\projects\\blah\\blah\\blah.cs:line blah For reference, the configuration goes like so <configuration> <configSections> ... normal sections here that work just fine, followed by ... <sectionGroup name="threadSettings" type="System.Configuration.NameValueSectionHandler"> <section name="T1" type="System.Configuration.DictionarySectionHandler"/> <section name="T2" type="System.Configuration.DictionarySectionHandler"/> <section name="T3" type="System.Configuration.DictionarySectionHandler"/> </sectionGroup> </configSections> <applicationSettings /> <threadSettings> <T1> <add key="key-here" value="value-here"/> </T1> ... T2 and T3 here as well, thats not interesting ... </threadSettings> </configuration> If I remove the actual sections and the definition for the custom section groups, I am able to read / write settings just fine and even call Save just fine. Obviously the custom section groups could be setup a little nicer but I can't fix that so I'm wondering: Is it possible to get the Configuration object to save if it has custom sectionGroups of the NameValueSectionHandler type

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• FireandForget delegate - c#

  - by uno

  I came across this link, link text In the article, where the author has definition of this method static void WriteIt(string first, string second, int num) I changed that in my test app to this static void WriteIt(CustomerObject Customer) { fileIO.CreateFile(XMLUtil.Serialize(Customer)); } Where public static string Serialize(object o) { System.Xml.Serialization.XmlSerializerNamespaces ns = new System.Xml.Serialization.XmlSerializerNamespaces(); ns.Add("", ""); return Serialize(o, ns); } public static string Serialize(object o, XmlSerializerNamespaces ns) { try { using (System.IO.MemoryStream m = new System.IO.MemoryStream()) { //serialize messagelist to xml XmlSerializer serializer = new XmlSerializer(o.GetType(), ""); if (ns != null) serializer.Serialize(m, o, ns); else serializer.Serialize(m, o); m.Position = 0; byte[] b = new byte[m.Length]; m.Read(b, 0, b.Length); return System.Text.UTF8Encoding.UTF8.GetString(b); } } catch (Exception ex) { return "Ex = " + ex.ToString(); } } This method always gives an exception static void EndWrapperInvoke (IAsyncResult ar) { wrapperInstance.EndInvoke(ar); ar.AsyncWaitHandle.Close(); } Stacktrace: Server stack trace: at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner) at System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Delegate.DynamicInvokeImpl(Object[] args) at System.Delegate.DynamicInvoke(Object[] args) at SRC.FileMover.ThreadUtil.InvokeWrappedDelegate(Delegate d, Object[] args) at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs) at System.Runtime.Remoting.Messaging.StackBuilderSink.PrivateProcessMessage(RuntimeMethodHandle md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs) at System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink) Exception rethrown at [0]: at System.Runtime.Remoting.Proxies.RealProxy.EndInvokeHelper(Message reqMsg, Boolean bProxyCase) at System.Runtime.Remoting.Proxies.RemotingProxy.Invoke(Object NotUsed, MessageData& msgData) at SRC.FileMover.ThreadUtil.DelegateWrapper.EndInvoke(IAsyncResult result) at SRC.FileMover.ThreadUtil.EndWrapperInvoke(IAsyncResult ar) at System.Runtime.Remoting.Messaging.AsyncResult.SyncProcessMessage(IMessage msg) at System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(IMessage msg, IMessageSink replySink) at System.Runtime.Remoting.Proxies.AgileAsyncWorkerItem.DoAsyncCall() at System.Runtime.Remoting.Proxies.AgileAsyncWorkerItem.ThreadPoolCallBack(Object o) at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack) at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state) UPDATE 1: Trying to run my app and get the full exception. It seems like its happening at different locations. I will repost my ? again shortly. I think it may be wise if I can post my application. Can i upload a .zip file or is it better to just post the .cs code that I am using?

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• KISS: Simple C# application which communicates with a RESTful web service.

  - by Workshop Alex

  Following the KISS principle, I suddenly realised the following: In .NET, you can use the Entity Model Framework to wrap around a database. This model can be exposed as a web service through WCF. This web service would have a very standardized definition. A client application could be created which could consume any such RESTful web service. I don't want to re-invent the wheel and it wouldn't surprise me if someone has already done this, so my question is simple: Has anyone already created a simple (desktop, not web) client application that can consume a RESTful service that's based on the Entity Framework and which will allow the user to read and write data directly to this service? Otherwise, I'll just have to "invent" this myself. :-)Problem is, the database layer and RESTful service is already finished. The RESTful service will only stay in the project during it's development phase, since we can use the database-layer assembly directly from the web applications that are build around it. When the web application is deployed, the RESTful services are just kept out of the deployment. But the database has a lot of data to manage over nearly 50 tables. When developing against a local database, we can have straight access to the database so I wouldn't need this tool for this. When it's deployed, the web application would be the only way to access the data so I could not use this tool. But we're also having a test phase where the database is stored on another system outside the local domain and this database is not available for developers. Only administrators have direct access to this database, making tests a bit more complex. However, through the RESTful service, I can still access the data directly. Thus, when some test goes wrong, I can repair the data through this connection or just create a copy of the data for tests on my local system. There's plenty of other functionality and it's even possible to just open the URL to a table service straight in Excel or XMLSpy to see the contents. But when I want to write something back, I have to write special code to do just that. A generic tool that would allow me to access the data and modify it would be easier. Since it's a generic setup around the ADO.NET Data services, this should be reasonable easy too. Thus, I can do it but hoped someone else has already done something similar. But it appears that there's no such tool made yet...

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• Calling "Base-Getter" in Overriding Getter of Property

  - by scherand

  I have a base class "Parent" like this: using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication1 { class Parent { private int parentVirtualInt = -1; public virtual int VirtualProperty { get { return parentVirtualInt; } set { if(parentVirtualInt != value) { parentVirtualInt = value; } } } } } and a child class like this: using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication1 { class Child : Parent { public override int VirtualProperty { get { if(base.VirtualProperty > 0) { throw new ApplicationException("Dummy Ex"); } return base.VirtualProperty; } set { if(base.VirtualProperty != value) { base.VirtualProperty = value; } } } } } Note that the getter in Child is calling the getter of Parent (or at least this is what I intend). I now use the "Child" class by instantiating it, assigning a value (let's say 4) to its VirtualProperty and then reading the property again. Child c = new Child(); c.VirtualProperty = 4; Console.Out.WriteLine("Child.VirtualProperty: " + c.VirtualProperty); When I run this, I obviously get an ApplicationException saying "Dummy Ex". But if I set a breakpoint on the line if(base.VirtualProperty > 0) in Child and check the value of base.VirtualProperty (by hovering the mouse over it) before the exception can be thrown (I assume(d)), I already get the Exception. From this I convey that the statement base.VirtualProperty in the "Child-Getter calls itself"; kind of. What I would like to achieve is the same behavior I get when I change the definition of parentVirutalInt (in Parent) to protected and use base.parentVirtualInt in the Getter of Child instead of base.VirtualProperty. And I don't yet see why this is not working. Can anybody shed some light on this? I feel that overridden properties behave differently than overridden methods? By the way: I am doing something very similar with subclassing a class I do not have any control over (this is the main reason why my "workaround" is not an option). Kind regards

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• Challenge: Neater way of currying or partially applying C#4's string.Join

  - by Damian Powell

  Background I recently read that .NET 4's System.String class has a new overload of the Join method. This new overload takes a separator, and an IEnumerable<T> which allows arbitrary collections to be joined into a single string without the need to convert to an intermediate string array. Cool! That means I can now do this: var evenNums = Enumerable.Range(1, 100) .Where(i => i%2 == 0); var list = string.Join(",",evenNums); ...instead of this: var evenNums = Enumerable.Range(1, 100) .Where(i => i%2 == 0) .Select(i => i.ToString()) .ToArray(); var list = string.Join(",", evenNums); ...thus saving on a conversion of every item to a string, and then the allocation of an array. The Problem However, being a fan of the functional style of programming in general, and method chaining in C# in particular, I would prefer to be able to write something like this: var list = Enumerable.Range(1, 100) .Where(i => i%2 == 0) .string.Join(","); This is not legal C# though. The closest I've managed to get is this: var list = Enumerable.Range(1, 100) .Where(i => i%2 == 0) .ApplyTo( Functional.Curry<string, IEnumerable<object>, string> (string.Join)(",") ); ...using the following extension methods: public static class Functional { public static TRslt ApplyTo<TArg, TRslt>(this TArg arg, Func<TArg, TRslt> func) { return func(arg); } public static Func<T1, Func<T2, TResult>> Curry<T1, T2, TResult>(this Func<T1, T2, TResult> func) { Func<Func<T1, T2, TResult>, Func<T1, Func<T2, TResult>>> curried = f => x => y => f(x, y); return curried(func); } } This is quite verbose, requires explicit definition of the parameters and return type of the string.Join overload I want to use, and relies upon C#4's variance features because we are defining one of the arguments as IEnumerable rather than IEnumerable. The Challenge Can you find a neater way of achieving this using the method-chaining style of programming?

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• How can I use Web Services Core to send a complex type as a parameter to a SOAP API method

  - by Matthew Brindley

  I don't do much Cocoa programming, so I'm probably missing something obvious, so please excuse the basic question. I have a SOAP method that expects a complex type as a paramater. Here's some WSDL: <s:element name="SaveTestResult"> <s:complexType> <s:sequence> <s:element minOccurs="0" maxOccurs="1" name="result" type="tns:TestItemResponse" /> </s:sequence> </s:complexType> </s:element> Here's the definition of the complex type "TestItemResponse": <s:complexType name="TestItemResponse"> <s:sequence> <s:element minOccurs="1" maxOccurs="1" name="TestItemRequestId" type="s:int" /> <s:element minOccurs="1" maxOccurs="1" name="ExternalId" type="s:int" /> <s:element minOccurs="0" maxOccurs="1" name="ApiId" type="s:string" /> <s:element minOccurs="0" maxOccurs="1" name="InboxGuid" type="s:string" /> <s:element minOccurs="0" maxOccurs="1" name="SpamResult" type="tns:SpamResult" /> <s:element minOccurs="0" maxOccurs="1" name="ResultImageSet" type="tns:ResultImageSet" /> <s:element minOccurs="1" maxOccurs="1" name="ExclusiveUseMailAccountId" type="s:int" /> <s:element minOccurs="1" maxOccurs="1" name="State" type="tns:TestItemResponseState" /> <s:element minOccurs="0" maxOccurs="1" name="ErrorShortDescription" type="s:string" /> <s:element minOccurs="0" maxOccurs="1" name="ErrorFullDescription" type="s:string" /> </s:sequence> </s:complexType> I've been using Web Services Core to call a SOAP API method that requires a simple string param, that works great. That same method returns a complex type which WSC converted into nested NSDictionaries, so no problems there. So I assumed I'd be able to convert my local TestItemResponse class into an NSDictionary and then use that as the complex type param. It almost worked, but unfortunately WSC set the object's type as "Dictionary", instead of "TestItemResponse", and the server complained. <TestItemResponse xsi:type=\"SOAP-ENC:Dictionary\"> <ErrorFullDescription xsi:type=\"xsd:string\">foo</ErrorFullDescription> ... I can't seem to find anything that allows you to override the type WSC assigns to the element in the SOAP XML. I've been using code adapted from here, I'm happy to list it, it's just quite long and this is already the longest SO question I've ever posted.

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• wxPython ListCtrl Column Ignores Specific Fields

  - by g.d.d.c

  I'm rewriting this post to clarify some things and provide a full class definition for the Virtual List I'm having trouble with. The class is defined like so: from wx import ListCtrl, LC_REPORT, LC_VIRTUAL, LC_HRULES, LC_VRULES, \ EVT_LIST_COL_CLICK, EVT_LIST_CACHE_HINT, EVT_LIST_COL_RIGHT_CLICK, \ ImageList, IMAGE_LIST_SMALL, Menu, MenuItem, NewId, ITEM_CHECK, Frame, \ EVT_MENU class VirtualList(ListCtrl): def __init__(self, parent, datasource = None, style = LC_REPORT | LC_VIRTUAL | LC_HRULES | LC_VRULES): ListCtrl.__init__(self, parent, style = style) self.columns = [] self.il = ImageList(16, 16) self.Bind(EVT_LIST_CACHE_HINT, self.CheckCache) self.Bind(EVT_LIST_COL_CLICK, self.OnSort) if datasource is not None: self.datasource = datasource self.Bind(EVT_LIST_COL_RIGHT_CLICK, self.ShowAvailableColumns) self.datasource.list = self self.Populate() def SetDatasource(self, datasource): self.datasource = datasource def CheckCache(self, event): self.datasource.UpdateCache(event.GetCacheFrom(), event.GetCacheTo()) def OnGetItemText(self, item, col): return self.datasource.GetItem(item, self.columns[col]) def OnGetItemImage(self, item): return self.datasource.GetImg(item) def OnSort(self, event): self.datasource.SortByColumn(self.columns[event.Column]) self.Refresh() def UpdateCount(self): self.SetItemCount(self.datasource.GetCount()) def Populate(self): self.UpdateCount() self.datasource.MakeImgList(self.il) self.SetImageList(self.il, IMAGE_LIST_SMALL) self.ShowColumns() def ShowColumns(self): for col, (text, visible) in enumerate(self.datasource.GetColumnHeaders()): if visible: self.columns.append(text) self.InsertColumn(col, text, width = -2) def Filter(self, filter): self.datasource.Filter(filter) self.UpdateCount() self.Refresh() def ShowAvailableColumns(self, evt): colMenu = Menu() self.id2item = {} for idx, (text, visible) in enumerate(self.datasource.columns): id = NewId() self.id2item[id] = (idx, visible, text) item = MenuItem(colMenu, id, text, kind = ITEM_CHECK) colMenu.AppendItem(item) EVT_MENU(colMenu, id, self.ColumnToggle) item.Check(visible) Frame(self, -1).PopupMenu(colMenu) colMenu.Destroy() def ColumnToggle(self, evt): toggled = self.id2item[evt.GetId()] if toggled[1]: idx = self.columns.index(toggled[2]) self.datasource.columns[toggled[0]] = (self.datasource.columns[toggled[0]][0], False) self.DeleteColumn(idx) self.columns.pop(idx) else: self.datasource.columns[toggled[0]] = (self.datasource.columns[toggled[0]][0], True) idx = self.datasource.GetColumnHeaders().index((toggled[2], True)) self.columns.insert(idx, toggled[2]) self.InsertColumn(idx, toggled[2], width = -2) self.datasource.SaveColumns() I've added functions that allow for Column Toggling which facilitate my description of the issue I'm encountering. On the 3rd instance of this class in my application the Column at Index 1 will not display String values. Integer values are displayed properly. If I add print statements to my OnGetItemText method the values show up in my console properly. This behavior is not present in the first two instances of this class, and my class does not contain any type checking code with respect to value display. It was suggested by someone on the wxPython users' group that I create a standalone sample that demonstrates this issue if I can. I'm working on that, but have not yet had time to create a sample that does not rely on database access. Any suggestions or advice would be most appreciated. I'm tearing my hair out on this one.

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• Soon to be PhD in Computer Science - Which Path to Follow?

  - by mttr

  I am going to submit my PhD thesis within the next six months. My PhD is on managing the availabiity of large-scale distributed systems, so I have some experience actually building non-trivial systems (+ I have four years experience working as a programmer). I am now trying to figure out what I should do following the PhD. I enjoy research (a quick definition: identify problem, come up with solution, ask interesting questions, find ways to answer them, build system, experiment, contribute some new knowledge and publish). I also like teaching and supervising students. It would seem that a career in academia is the ideal thing to do (can work on non-trivial problems and contribute something of use to some or more people). However, a career in academia has two significant drawbacks. First, it can be difficult to gain access to real systems with real users which then display real problems. This creates the danger that you do work that seems important (to you and maybe to some of your colleagues), but is not really relevant to anything or anyone. Second, the pay is pretty sad. Apparently, you have to sacrifice this for the privilege of doing research. I enjoy programming, but don't just want to hack some web-based system for the rest of my life. That is, working in IT for a bank is not a future I see myself enjoying. I want to work on interesting problms (that's difficult to define clearly): things where you don't know how to start, that take some time to figure out and attack, that require a rigorous approach to demonstrate that the problem has been solved, and problems that need a solution in the real world. Give the experience of people on stackoverflow, what do you think suitable options are and why (or alternatively, what gaps in my thinking does the above reveal)? Is industrial research (aka IBM Research, Microsoft Research) the only alternative avenue to a career in academia? What other areas, companies, occupations, etc. could provide me with stimulating, inspiring work? Which regions, countries am I most likely to find such work? Please share your experience.

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• Common DataAnnotations in ASP.Net MVC2

  - by Scott Mayfield

  Howdy, I have what should be a simple question. I have a set of validations that use System.CompontentModel.DataAnnotations . I have some validations that are specific to certain view models, so I'm comfortable with having the validation code in the same file as my models (as in the default AccountModels.cs file that ships with MVC2). But I have some common validations that apply to several models as well (valid email address format for example). When I cut/paste that validation to the second model that needs it, of course I get a duplicate definition error because they're in the same namespace (projectName.Models). So I thought of removing the common validations to a separate class within the namespace, expecting that all of my view models would be able to access the validations from there. Unexpectedly, the validations are no longer accessible. I've verified that they are still in the same namespace, and they are all public. I wouldn't expect that I would have to have any specific reference to them (tried adding using statement for the same namespace, but that didn't resolve it, and via the add references dialog, a project can't reference itself (makes sense). So any idea why public validations that have simply been moved to another file in the same namespace aren't visible to my models? CommonValidations.cs using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.ComponentModel; using System.ComponentModel.DataAnnotations; using System.Text.RegularExpressions; namespace ProjectName.Models { public class CommonValidations { [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = true, Inherited = true)] public sealed class EmailFormatValidAttribute : ValidationAttribute { public override bool IsValid(object value) { if (value != null) { var expression = @"^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$"; return Regex.IsMatch(value.ToString(), expression); } else { return false; } } } } } And here's the code that I want to use the validation from: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.ComponentModel; using System.ComponentModel.DataAnnotations; using Growums.Models; namespace ProjectName.Models { public class PrivacyModel { [Required(ErrorMessage="Required")] [EmailFormatValid(ErrorMessage="Invalid Email")] public string Email { get; set; } } }

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• How to handle float values in a plist

  - by Banjer

  I'm reading in a plist from a web server, generated with some php. When I read that into an NSArray in my iphone app, and then spit the NSArray out with NSLog to check it out, I see that the float values are treated as strings. I would like the "distance" values to be treated as numeric and not strings. This plist is displayed in a table view where it can be sorted by distance, but the problem is is distance is sorted as a string, so I get some funny sorting results. Can I convert the distance values to float from string in the NSArray? Or maybe theres a simpler solution like tweaking the plist definition, or maybe something in the NSMutableURLRequest code? My plist looks like this: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <array> <dict> <key>name</key> <string>Pizza Joint</string> <key>distance</key> <string>2.1</string> </dict> <dict> <key>name</key> <string>Burger Kang</string> <key>distance</key> <string>5</string> </dict> </array> </plist> After reading it into an NSArray, it looks like this per NSLog: result: ( { distance = "2.1"; name = "Pizza Joint"; }, { distance = 5; name = "Burger Kang"; } ) Here is the Objective-C code that retrieves the plist: // Set up url request // postData and postLength are left out, but I can post in this question if needed. NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease]; [request setURL:[NSURL URLWithString:@"http://mysite.com/get_plist.php"]]; [request setHTTPMethod:@"POST"]; [request setValue:postLength forHTTPHeaderField:@"Content-Length"]; [request setValue:@"application/x-www-form-urlencoded charset=utf-8" forHTTPHeaderField:@"Content-Type"]; [request setHTTPBody:postData]; NSError *error; NSURLResponse *response; NSData *result = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; NSString *string = [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding]; // libraryContent is an NSArray self.libraryContent = [string propertyList]; NSLog(@"result: %@", self.libraryContent);

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• Where to put a glossary of important terms and patterns in documentation?

  - by Tetha

  Greetings. I want to document certain patterns in the code in order to build up a consistent terminology (in order to easen communication about the software). I am, however, unsure, where to define the terms given. In order to get on the same level, an example: I have a code generator. This code generator receives a certain InputStructure from the Parser (yes, the name InputStructure might be less than ideal). This InputStructure is then transformed into various subsequent datastructures (like an abstract description of the validation process). Each of these datastructures can be either transformed into another value of the same datastructure or it can be transformed into the next datastructure. This should sound like Pipes and Filters to some degree. Given this, I call an operation which takes a datastructures and constructs a value of the same datastructure a transformation, while I call an operation which takes a datastructure and produces a different follow-up datastructure a derivation. The final step of deriving a string containing code is called emitting. (So, overall, the codegenerator takes the input-structure and transforms, transforms, derives, transforms, derives and finally emits). I think emphasizing these terms will be benefitial in communications, because then it is easy to talk about things. If you hear "transformation", you know "Ok, I only need to think about these two datastructures", if you hear "emitting", you know "Ok, I only need to know this datastructure and the target language.". However, where do I document these patterns? The current code base uses visitors and offers classes called like ValidatorTransformationBase<ResultType> (or InputStructureTransformationBase<ResultType>, and so one and so on). I do not really want to add the definition of such terms to the interfaces, because in that case, I'd have to repeat myself on each and every interface, which clearly violates DRY. I am considering to emphasize the distinction between Transformations and Derivations by adding further interfaces (I would have to think about a better name for the TransformationBase-classes, but then I could do thinks like ValidatorTransformation extends ValidatorTransformationBase<Validator>, or ValidatorDerivationFromInputStructure extends InputStructureTransformation<Validator>). I also think I should add a custom page to the doxygen documentation already existing, as in "Glossary" or "Architecture Principles", which contains such principles. The only disadvantage of this would be that a contributor will need to find this page in order to actually learn about this. Am I missing possibilities or am I judging something wrong here in your opinion? -- Regards, Tetha

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• quartz: preventing concurrent instances of a job in jobs.xml

  - by Jason S

  This should be really easy. I'm using Quartz running under Apache Tomcat 6.0.18, and I have a jobs.xml file which sets up my scheduled job that runs every minute. What I would like to do, is if the job is still running when the next trigger time rolls around, I don't want to start a new job, so I can let the old instance complete. Is there a way to specify this in jobs.xml (prevent concurrent instances)? If not, is there a way I can share access to an in-memory singleton within my application's Job implementation (is this through the JobExecutionContext?) so I can handle the concurrency myself? (and detect if a previous instance is running) update: After floundering around in the docs, here's a couple of approaches I am considering, but either don't know how to get them to work, or there are problems. Use StatefulJob. This prevents concurrent access... but I'm not sure what other side-effects would occur if I use it, also I want to avoid the following situation: Suppose trigger times would be every minute, i.e. trigger#0 = at time 0, trigger #1 = 60000msec, #2 = 120000, #3 = 180000, etc. and the trigger#0 at time 0 fires my job which takes 130000msec. With a plain Job, this would execute triggers #1 and #2 while job trigger #0 is still running. With a StatefulJob, this would execute triggers #1 and #2 in order, immediately after #0 finishes at 130000. I don't want that, I want #1 and #2 not to run and the next trigger that runs a job should take place at #3 (180000msec). So I still have to do something else with StatefulJob to get it to work the way I want, so I don't see much of an advantage to using it. Use a TriggerListener to return true from vetoJobExecution(). Although implementing the interface seems straightforward, I have to figure out how to setup one instance of a TriggerListener declaratively. Can't find the docs for the xml file. Use a static shared thread-safe object (e.g. a semaphore or whatever) owned by my class that implements Job. I don't like the idea of using singletons via the static keyword under Tomcat/Quartz, not sure if there are side effects. Also I really don't want them to be true singletons, just something that is associated with a particular job definition. Implement my own Trigger which extends SimpleTrigger and contains shared state that could run its own TriggerListener. Again, I don't know how to setup the XML file to use this trigger rather than the standard <trigger><simple>...</simple></trigger>.

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• dynamic char array sizing

  - by droseman

  Hello, In my application, I have a char array defined which can take one of three options: "okay", "high", "low" which are then sent down a serial port to a remote device. I currently have the array sized to take the 4 character words plus carriage return and line feed, but when I have to send "low" I get a null character in the strings, which I am concerned would confuse the host terminal. array definition char mod1_status_char[6] = {'0','0','0','0','0','0'}; char mod2_status_char[6] = {'0','0','0','0','0','0'}; char mod3_status_char[6] = {'0','0','0','0','0','0'}; sample of switch case statement: void DCOKStatus(uint8_t *ptr_status) { uint8_t status = *ptr_status; switch (status) { case 0x00: strcpy(mod1_status_char, "okay"); strcpy(mod2_status_char, "okay"); strcpy(mod3_status_char, "okay"); break; case 0x10: strcpy(mod1_status_char, "okay"); strcpy(mod2_status_char, "okay"); strcpy(mod3_status_char, "low"); break; } This is the struct which makes the message string to send strcpy(MsgStatus_on.descriptor_msg, "$psu_"); MsgStatus_on.address01 = hex_addr[0]; MsgStatus_on.address02 = hex_addr[1]; MsgStatus_on.space01 = 0x20; strcpy(MsgStatus_on.cmdmsg01, "op_en op1_"); strcpy(MsgStatus_on.statusmsg01, mod1_status_char); MsgStatus_on.space02 = 0x20; strcpy(MsgStatus_on.cmdmsg02, "op2_"); strcpy(MsgStatus_on.statusmsg02, mod2_status_char); MsgStatus_on.space03 = 0x20; strcpy(MsgStatus_on.cmdmsg03, "op3_"); strcpy(MsgStatus_on.statusmsg03, mod3_status_char); MsgStatus_on.CR = 0x0D; MsgStatus_on.LF = 0x0A; and this sends the message void USARTWrite(char *object, uint32_t size) { GPIO_SetBits(GPIOB, GPIO_Pin_1); char *byte; for (byte = object; size--; ++byte) { USART_SendData(USART1,*byte); } Would anyone be able to suggest a good approach to dynamically size the array to one character shorter when I need to send "low"? Thanks

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• Can I append to a preprocessor macro?

  - by JCSalomon

  Is there any way in standard C—or with GNU extensions—to append stuff to a macro definition? E.g., given a macro defined as #define quux_list X(foo) X(bar) can I append X(bas) so that it now expands as if I’d defined it #define quux_list X(foo) X(bar) X(bas)? I’m playing with discriminated/tagged unions along these lines: struct quux_foo { int x; }; struct quux_bar { char *s; }; struct quux_bas { void *p; }; enum quux_type {quux_foo, quux_bar, quux_bas}; struct quux { enum quux_type type; union { struct quux_foo foo; struct quux_bar bar; struct quux_bas bas; } t; }; I figure this is a good place for the X-macro. If I define a macro #define quux_table X(foo) X(bar) X(bas) the enumeration & structure can be defined thus, and never get out of sync: #define X(t) quux_ ## t, enum quux_type {quux_table}; #undef X #define X(t) struct quux_ ## t t; struct quux { enum quux_type type; union {quux_table} t; }; #undef X Of course, the quux_* structures can get out of sync, so I’d like to do something like this, only legally: struct quux_foo { int x; }; #define quux_table quux_table X(foo) struct quux_bar { char *s; }; #define quux_table quux_table X(bar) struct quux_bas { void *p; }; #define quux_table quux_table X(bas) (Well, what I really want to be able to do is something like member_struct(quux, foo) { int x; }; but I’m well aware that macros cannot be (re)defined from within macros.) Anyhow, that’s my motivating example. Is there a way to accomplish this? Boost.Preprocessor examples are fine, if you can show me how to make the X-macro technique work with that library.

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• ActiveMQ 5.2.0 + REST + HTTP POST = java.lang.OutOfMemoryError

  - by Bruce Loth

  First off, I am a newbie when it comes to JMS & ActiveMQ. I have been looking into a messaging solution to serve as middleware for a message producer that will insert XML messages into a queue via HTTP POST. The producer is an existing system written in C++ that cannot be modified (so Java and the C++ API are out). Using the "demo" examples and some trial and error, I have cobbled together a working example of what I want to do (on a windows box). The web.xml I configured in a test directory under "webapps" specifies that the HTTP POST messages received from the producer are to be handled by the MessageServlet. I added a line for the text app in "activemq.xml" ('ow' is the test app dir): I created a test script to "insert" messages into the queue which works well. The problem I am running into is that it as I continue to insert messages via REST/HTTP POST, the memory consumption and thread count used by ActiveMQ continues to rise (It happens when I have timely consumers as well as slow or non-existent consumers). When memory consumption gets around 250MB's and the thread count exceeds 5000 (as shown in windows task manager), ActiveMQ crashes and I see this in the log: Exception in thread "ActiveMQ Transport Initiator: vm://localhost#3564" java.lang.OutOfMemoryError: unable to create new native thread It is as if Jetty is spawning a new thread to handle each HTTP POST and the thread never dies. I did look at this page: http://activemq.apache.org/javalangoutofmemory.html and tried but that didn't fix the problem (although I didn't fully understand the implications of the change either). Does anyone have any ideas? Thanks! Bruce Loth PS - I included the "test message producer" python script below for what it is worth. I created batches of 100 messages and continued to run the script manually from the command line while watching the memory consumption and thread count of ActiveMQ in task manager. def foo(): import httplib, urllib body = "<?xml version='1.0' encoding='UTF-8'?>\n \ <ROOT>\n \ [snip: xml deleted to save space] </ROOT>" headers = {"content-type": "text/xml", "content-length": str(len(body))} conn = httplib.HTTPConnection("127.0.0.1:8161") conn.request("POST", "/ow/message/RDRCP_Inbox?type=queue", body, headers) response = conn.getresponse() print response.status, response.reason data = response.read() conn.close() ## end method definition ## Begin test code count = 0; while(count < 100): # Test with batches of 100 msgs count += 1 foo()

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• .NET: Interface Problem VB.net Getter Only Interface

  - by snmcdonald

  Why does an interface override a class definition and violate class encapsulation? I have included two samples below, one in C# and one in VB.net? VB.net Module Module1 Sub Main() Dim testInterface As ITest = New TestMe Console.WriteLine(testInterface.Testable) ''// Prints False testInterface.Testable = True ''// Access to Private!!! Console.WriteLine(testInterface.Testable) ''// Prints True Dim testClass As TestMe = New TestMe Console.WriteLine(testClass.Testable) ''// Prints False ''//testClass.Testable = True ''// Compile Error Console.WriteLine(testClass.Testable) ''// Prints False End Sub End Module Public Class TestMe : Implements ITest Private m_testable As Boolean = False Public Property Testable As Boolean Implements ITest.Testable Get Return m_testable End Get Private Set(ByVal value As Boolean) m_testable = value End Set End Property End Class Interface ITest Property Testable As Boolean End Interface C# using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace InterfaceCSTest { class Program { static void Main(string[] args) { ITest testInterface = new TestMe(); Console.WriteLine(testInterface.Testable); testInterface.Testable = true; Console.WriteLine(testInterface.Testable); TestMe testClass = new TestMe(); Console.WriteLine(testClass.Testable); //testClass.Testable = true; Console.WriteLine(testClass.Testable); } } class TestMe : ITest { private bool m_testable = false; public bool Testable { get { return m_testable; } private set { m_testable = value; } } } interface ITest { bool Testable { get; set; } } } More Specifically How do I implement a interface in VB.net that will allow for a private setter. For example in C# I can declare: class TestMe : ITest { private bool m_testable = false; public bool Testable { get { return m_testable; } private set //No Compile Error here! { m_testable = value; } } } interface ITest { bool Testable { get; } } However, if I declare an interface property as readonly in VB.net I cannot create a setter. If I create a VB.net interface as just a plain old property then interface declarations will violate my encapsulation. Public Class TestMe : Implements ITest Private m_testable As Boolean = False Public ReadOnly Property Testable As Boolean Implements ITest.Testable Get Return m_testable End Get Private Set(ByVal value As Boolean) ''//Compile Error m_testable = value End Set End Property End Class Interface ITest ReadOnly Property Testable As Boolean End Interface So my question is, how do I define a getter only Interface in VB.net with proper encapsulation? I figured the first example would have been the best method. However, it appears as if interface definitions overrule class definitions. So I tried to create a getter only (Readonly) property like in C# but it does not work for VB.net. Maybe this is just a limitation of the language?

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• Hibernate + Spring : cascade deletion ignoring non-nullable constraints

  - by E.Benoît

  Hello, I seem to be having one weird problem with some Hibernate data classes. In a very specific case, deleting an object should fail due to existing, non-nullable relations - however it does not. The strangest part is that a few other classes related to the same definition behave appropriately. I'm using HSQLDB 1.8.0.10, Hibernate 3.5.0 (final) and Spring 3.0.2. The Hibernate properties are set so that batch updates are disabled. The class whose instances are being deleted is: @Entity( name = "users.Credentials" ) @Table( name = "credentials" , schema = "users" ) public class Credentials extends ModelBase { private static final long serialVersionUID = 1L; /* Some basic fields here */ /** Administrator credentials, if any */ @OneToOne( mappedBy = "credentials" , fetch = FetchType.LAZY ) public AdminCredentials adminCredentials; /** Active account data */ @OneToOne( mappedBy = "credentials" , fetch = FetchType.LAZY ) public Account activeAccount; /* Some more reverse relations here */ } (ModelBase is a class that simply declares a Long field named "id" as being automatically generated) The Account class, which is one for which constraints work, looks like this: @Entity( name = "users.Account" ) @Table( name = "accounts" , schema = "users" ) public class Account extends ModelBase { private static final long serialVersionUID = 1L; /** Credentials the account is linked to */ @OneToOne( optional = false ) @JoinColumn( name = "credentials_id" , referencedColumnName = "id" , nullable = false , updatable = false ) public Credentials credentials; /* Some more fields here */ } And here is the AdminCredentials class, for which the constraints are ignored. @Entity( name = "admin.Credentials" ) @Table( name = "admin_credentials" , schema = "admin" ) public class AdminCredentials extends ModelBase { private static final long serialVersionUID = 1L; /** Credentials linked with an administrative account */ @OneToOne( optional = false ) @JoinColumn( name = "credentials_id" , referencedColumnName = "id" , nullable = false , updatable = false ) public Credentials credentials; /* Some more fields here */ } The code that attempts to delete the Credentials instances is: try { if ( account.validationKey != null ) { this.hTemplate.delete( account.validationKey ); } this.hTemplate.delete( account.languageSetting ); this.hTemplate.delete( account ); } catch ( DataIntegrityViolationException e ) { return false; } Where hTemplate is a HibernateTemplate instance provided by Spring, its flush mode having been set to EAGER. In the conditions shown above, the deletion will fail if there is an Account instance that refers to the Credentials instance being deleted, which is the expected behaviour. However, an AdminCredentials instance will be ignored, the deletion will succeed, leaving an invalid AdminCredentials instance behind (trying to refresh that instance causes an error because the Credentials instance no longer exists). I have tried moving the AdminCredentials table from the admin DB schema to the users DB schema. Strangely enough, a deletion-related error is then triggered, but not in the deletion code - it is triggered at the next query involving the table, seemingly ignoring the flush mode setting. I've been trying to understand this for hours and I must admit I'm just as clueless now as I was then.

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• C++ EZWindows Linker Errors when trying to run demos

  - by Brent Nash

  I'm attempting to download and use the EZWindows ( http://www.cs.virginia.edu/c++programdesign/software/ ) SPARC installation (the http://www.cs.virginia.edu/c++programdesign/software/EzWindows2a-SPARC.tar.gz file). When trying to build some of the examples that come with it, I'm getting some linker errors that I just can't figure out. Here's the result of the uname -a command on the machine I'm running on (on which I am NOT an administrator): SunOS AAA.BBB.edu 5.10 Generic_138888-07 sun4v sparc SUNW,T5240 And here is the result of the g++ -v command: gcc version 2.95.2 19991024 (release) If you untar/unzip the package, I'm trying to compile the example in samples/chap03/lawn by simply doing "gmake" in that directory, here's what I get. Here's the error I get: bash-3.00$ gtar xfz EzWindows2a-SPARC.tar.gz gtar: Removing leading `./' from member names bash-3.00$ cd chap03/lawn bash-3.00$ gmake clean ; gmake rm -f *.o *~ lawn make lawn g++ -I/X11.6/include -I../../EzWindows/include -c prog3-5.cpp prog3-5.cpp: In function `int ApiMain()': prog3-5.cpp:75: warning: initialization to `long int' from `const float' prog3-5.cpp:85: warning: initialization to `int' from `float' prog3-5.cpp:86: warning: initialization to `int' from `float' g++ -o lawn prog3-5.o -L/X11.6/lib -R/X11.6/lib -lX11 -lsocket -L../../EzWindows/lib -lezwin -lXpm ld: warning: symbol `clog' has differing types: (file /usr/usc/gnu/gcc/2.95.2/lib/gcc-lib/sparc-sun-solaris2.6/2.95.2/libstdc++.so type=OBJT; file /lib/libm.so type=FUNC); /usr/usc/gnu/gcc/2.95.2/lib/gcc-lib/sparc-sun-solaris2.6/2.95.2/libstdc++.so definition taken Undefined first referenced symbol in file __dl__Q2t12basic_string3ZcZt18string_char_traits1ZcZt24__default_alloc_template2b0i03RepPv ../../EzWindows/lib/libezwin.a(WindowManager.o) __eh_pc ../../EzWindows/lib/libezwin.a(WindowManager.o) clone__Q2t12basic_string3ZcZt18string_char_traits1ZcZt24__default_alloc_template2b0i03Rep ../../EzWindows/lib/libezwin.a(WindowManager.o) ld: fatal: Symbol referencing errors. No output written to lawn collect2: ld returned 1 exit status *** Error code 1 make: Fatal error: Command failed for target `lawn' Current working directory /export/samfs-bcf/rcf-11/bnash/sparc/chap03/lawn gmake: *** [default] Error 1 This particular run was built using g++ 2.95.2, but I've also tried with versions 3.3.2 and 4.2.1 with other equally strange errors. I'm pretty sure that EZWindows requires a 2.x version of gcc & g++. I've tried to make sure that my LD_LIBRARY_PATH and PATH are setup to include everything that's needed, but it seems that may be incorrect. I'm running out of ideas. Anyone have any other ones?

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• Coldfusion Components:- The argument passed to the function is not of type numeric

  - by salim.vali

  Hi I have a simple form form.cfm:- <cfset Registr = createObject("component", "forms.Registr") /> <cfset setFoo = createObject('component','forms.Registr).putNUsr(username,password,rating) /> <form name="regFrm" action="#cgi.script_name#" method="post" onsubmit="submitform();" > <tr><td>Username:</td> <td><input type="text" name=" Username" value="#form. Username#" ></td></tr> <tr><td>Password:</td> <td><input class="" type="password" name="password" value="#form.password#" ></td></tr> <tr><td>Rate:</td> <select name="rating" > <option value="" ></option> <cfloop query="qGetReting"> <option value="#rating_id#" <cfif form. rating eq prof_id>selected</cfif> >#rating#</option> </cfloop> </select> </td> </tr> </form> Now there is this cfc called Registr.cfc in the "forms" folder which has an insert-function called 'putNUsr'the code for 'Registr.cfc' is as follows. <cfcomponent> <cffunction name="putNUsr" returntype="void" displayname="" output="no"> <cfargument name="password" type="string" required="true"> <cfargument name="rating" type="numeric" required="true"> <cfargument name="username" type="string" required="true"> <cfquery datasource="#application.xyz#" name="q_putNUsr"> insert into users (username , password , rating) values( <cfqueryparam value="#arguments. username#" cfsqltype="CF_SQL_VARCHAR" />, <cfqueryparam value="#arguments.password#" cfsqltype="CF_SQL_VARCHAR" />, <cfqueryparam value="#arguments.rating#" cfsqltype="CF_SQL_INTEGER" ) </cfquery> </cffunction> </cfcomponent> I am able to populate the DB with the data if I do not use the form field "rating" which is numeric. Else i am getting the error as follows:- The RATING argument passed to the putNUsr function is not of type numeric. If the component name is specified as a type of this argument, it is possible that either a definition file for the component cannot be found or is not accessible. KINDLY HELP -S Vali

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• More GCC link time issues: undefined reference to main

  - by vikramtheone

  Hi Guys, I'm writing software for a Cortex-A8 processor and I have to write some ARM assembly code to access specific registers. I'm making use of the gnu compilers and related tool chains, these tools are installed on the processor board(Freescale i.MX515) with Ubuntu. I make a connection to it from my host PC(Windows) using WinSCP and the PuTTY terminal. As usual I started with a simple C project having main.c and functions.s. I compile the main.c using GCC, assemble the functions.s using as and link the generated object files using once again GCC, but I get strange errors during this process. An important finding - Meanwhile, I found out that my assembly code may have some issues because when I individually assemble it using the command as -o functions.o functions.s and try running the generated functions.o using ./functions.o command, the bash shell is failing to recognize this file as an executable(on pressing tab functions.o is not getting selected/PuTTY is not highlighting the file). Can anyone suggest whats happening here? Are there any specific options I have to send, to GCC during the linking process? The errors I see are strange and beyond my understanding, I don't understand to what the GCC is referring. I'm pasting here the contents of main.c, functions.s, the Makefile and the list of errors. Help, please!!! Vikram main.c #include <stdio.h> #include <stdlib.h> int main(void) { puts("!!!Hello World!!!"); /* prints !!!Hello World!!! */ return EXIT_SUCCESS; } functions.s * Main program */ .equ STACK_TOP, 0x20000800 .text .global _start .syntax unified _start: .word STACK_TOP, start .type start, function start: movs r0, #10 movs r1, #0 .end Makefile all: hello hello: main.o functions.o gcc -o main.o functions.o main.o: main.c gcc -c -mcpu=cortex-a8 main.c functions.o: functions.s as -mcpu=cortex-a8 -o functions.o functions.s Errors ubuntu@ubuntu-desktop:~/Documents/Project/Others/helloworld$ make gcc -c -mcpu=cortex-a8 main.c as -mcpu=cortex-a8 -o functions.o functions.s gcc -o main.o functions.o functions.o: In function `_start': (.text+0x0): multiple definition of `_start' /usr/lib/gcc/arm-linux-gnueabi/4.3.3/../../../crt1.o:init.c:(.text+0x0): first defined here /usr/lib/gcc/arm-linux-gnueabi/4.3.3/../../../crt1.o: In function `_start': init.c:(.text+0x30): undefined reference to `main' collect2: ld returned 1 exit status make: *** [hello] Error 1

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• XSD sequence shows as abiguous!

  - by Tim C

  I have an XSD which was transformed from a RELAX NG schema with a few errors I am trying to fix. The big issue I have it with the following <xs:element name="list"> <xs:complexType> <xs:sequence> <xs:choice> <xs:sequence> <xs:element minOccurs="0" ref="preamble"/> <xs:element minOccurs="0" ref="title"/> </xs:sequence> <xs:sequence> <xs:element minOccurs="0" ref="title"/> <xs:element minOccurs="0" ref="preamble"/> </xs:sequence> </xs:choice> <xs:group maxOccurs="unbounded" ref="block-selectionListItem"/> </xs:sequence> <xs:attributeGroup ref="attlist-selectionList"/> </xs:complexType> </xs:element> As you can see the xs:choice block allows you to pick between two xs:sequence blocks. Seems to make sense except that Visual Studio gives the following warning on the second <xs:element minOccurs="0" ref="title/> element which is throwing everything off: Multiple definition of element 'title' causes the content model to become ambiguous. A content model must be formed such that during validation of an element information item sequence, the particle contained directly, indirectly or implicitly therein with which to attempt to validate each item in the sequence in turn can be uniquely determined without examining the content or attributes of that item, and without any information about the items in the remainder of the sequence. Because you can only choose one I do not see how this is ambiguous. Any help would be greatly appreciated! Edit: To be a bit more concise here are the possible outputs of the XML that would validate with this schema: <list> <preamble>My Preamble</preamble> <title>My Title</title> </list> or: <list> <title>My Title</title> <preamble>My Preamble</preamble> </list> As you can see it can be either one way or the other but not both. Also you could just have a title or a preamble and not both.

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• Is there any reasonable use of a function returning an anonymous struct?

  - by Akanksh

  Here is an (artificial) example of using a function that returns an anonymous struct and does "something" useful: #include <iostream> template<typename T> T* func( T* t, float a, float b ) { if(!t) { t = new T; t->a = a; t->b = b; } else { t->a += a; t->b += b; } return t; } struct { float a, b; }* foo(float a, float b) { if(a==0) return 0; return func(foo(a-1,b), a, b); } int main() { std::cout << foo(5,6)->a << std::endl; std::cout << foo(5,6)->b << std::endl; void* v = (void*)(foo(5,6)); float* f = (float*)(v); //[1] delete f now because I know struct is floats only. std::cout << f[0] << std::endl; std::cout << f[1] << std::endl; delete[] f; return 0; } There are a few points I would like to discuss: As is apparent, this code leaks, is there anyway I can NOT leak without knowing what the underlying struct definition is? see Comment [1]. I have to return a pointer to an anonymous struct so I can create an instance of the object within the templatized function func, can I do something similar without returning a pointer? I guess the most important, is there ANY (real-world) use for this at all? As the example given above leaks and is admittedly contrived. By the way, what the function foo(a,b) does is, to return a struct containing two numbers, the sum of all numbers from 1 to a and the product of a and b. EDIT: Maybe the line new T could use a boost::shared_ptr somehow to avoid leaks, but I haven't tried that. Would that work?

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• Fread binary file dynamic size string [C]

  - by Blackbinary

  I've been working on this assignment, where I need to read in "records" and write them to a file, and then have the ability to read/find them later. On each run of the program, the user can decide to write a new record, or read an old record (either by Name or #) The file is binary, here is its definition: typedef struct{ char * name; char * address; short addressLength, nameLength; int phoneNumber; }employeeRecord; employeeRecord record; The way the program works, it will store the structure, then the name, then the address. Name and address are dynamically allocated, which is why it is necessary to read the structure first to find the size of the name and address, allocate memory for them, then read them into that memory. For debugging purposes I have two programs at the moment. I have my file writing program, and file reading. My actual problem is this, when I read a file I have written, i read in the structure, print out the phone # to make sure it works (which works fine), and then fread the name (now being able to use record.nameLength which reports the proper value too). Fread however, does not return a usable name, it returns blank. I see two problems, either I haven't written the name to the file correctly, or I haven't read it in correctly. Here is how i write to the file: where fp is the file pointer. record.name is a proper value, so is record.nameLength. Also i am writing the name including the null terminator. (e.g. 'Jack\0') fwrite(&record,sizeof record,1,fp); fwrite(record.name,sizeof(char),record.nameLength,fp); fwrite(record.address,sizeof(char),record.addressLength,fp); And i then close the file. here is how i read the file: fp = fopen("employeeRecord","r"); fread(&record,sizeof record,1,fp); printf("Number: %d\n",record.phoneNumber); char *nameString = malloc(sizeof(char)*record.nameLength); printf("\nName Length: %d",record.nameLength); fread(nameString,sizeof(char),record.nameLength,fp); printf("\nName: %s",nameString); Notice there is some debug stuff in there (name length and number, both of which are correct). So i know the file opened properly, and I can use the name length fine. Why then is my output blank, or a newline, or something like that? (The output is just Name: with nothing after it, and program finishes just fine) Thanks for the help.

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• OpenGL Polygon Stipple Not Working On Different Machine

  - by FranticPedantic

  I have a situation where I am trying to draw a semi-transparent rectangle over a background that is not using openGL and so I can not use blending. I decided to use polygon stippling for a 'screen door transparency' effect as recommended by some. It works fine on my machine and some others, but on some machines with slightly old Intel graphics cards it's failing to render the rectangle at all. If I turn off polygon stipple, it renders fine (but without the stipple). I have compared many of the state variables that I thought might affect it (see code) between machines and they are all the same, and I get no errors. static const GLubyte stipplePatternChkr[128]; //definition omitted for clarity //but works on my machine // stipple the box glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glColor4ubv(Color(COLORREF_PADGRAY)); glEnable(GL_POLYGON_STIPPLE); glPolygonStipple(stipplePatternChkr); CRect rcStipple(dim); rcStipple.DeflateRect(padding - 1, padding - 1); glBegin(GL_QUADS); glVertex2i(rcStipple.left, rcStipple.bottom); glVertex2i(rcStipple.right, rcStipple.bottom); glVertex2i(rcStipple.right, rcStipple.top); glVertex2i(rcStipple.left, rcStipple.top); glEnd(); glDisable(GL_POLYGON_STIPPLE); int err = glGetError(); if (err != GL_NO_ERROR) { TRACE("glError(%s: %s)\n", s, gluErrorString(err)); } float x; glGetFloatv(GL_UNPACK_ALIGNMENT, &x); TRACE("unpack alignment %f\n", x); glGetFloatv(GL_UNPACK_IMAGE_HEIGHT, &x); TRACE("unpack height %f\n", x); glGetFloatv(GL_UNPACK_LSB_FIRST, &x); TRACE("unpack lsb %f\n", x); glGetFloatv(GL_UNPACK_ROW_LENGTH, &x); TRACE("unpack length %f\n", x); glGetFloatv(GL_UNPACK_SKIP_PIXELS, &x); TRACE("upnack skip %f\n", x); glGetFloatv(GL_UNPACK_SWAP_BYTES, &x); TRACE("upnack swap %f\n", x);

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• Undefined Behavior and Sequence Points Reloaded

  - by Nawaz

  Consider this topic a sequel of the following topic: Previous Installment Undefined Behavior and Sequence Points Let's revisit this funny and convoluted expression (the italicized phrases are taken from the above topic *smile* ): i += ++i; We say this invokes undefined-behavior. I presume that when say this, we implicitly assume that type of i is one of built-in types. So my question is: what if the type of i is a user-defined type? Say it's type is Index which is defined later in this post (see below). Would it still invoke undefined-behavior? If yes, why? Is it not equivalent to writing i.operator+=(i.operator ++()); or even syntactically simpler i.add(i.inc());? Or, do they too invoke undefined-behavior? If no, why not? After all, the object i gets modified twice between consecutive sequence points. Please recall the rule of thumb : an expression can modify an object's value only once between consecutive "sequence points. And if i += ++i is an expression, then it must invoke undefined-behavior. If so, then it's equivalents i.operator+=(i.operator ++()); and i.add(i.inc()); must also invoke undefined-behavior which seems to be untrue! (as far as I understand) Or, i += ++i is not an expression to begin with? If so, then what is it and what is the definition of expression? If it's an expression, and at the same time, it's behavior is also well-defined, then it implies that number of sequence points associated with an expression somehow depends on the type of operands involved in the expression. Am I correct (even partly)? By the way, how about this expression? a[++i] = i; //taken from the previous topic. but here type of `i` is Index. class Index { int state; public: Index(int s) : state(s) {} Index& operator++() { state++; return *this; } Index& operator+=(const Index & index) { state+= index.state; return *this; } operator int() { return state; } Index & add(const Index & index) { state += index.state; return *this; } Index & inc() { state++; return *this; } };

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