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  • How to JSON serialize math vector type in F#?

    - by The_Ghost
    Hello! I'm trying to serialize "vector" (Microsoft.FSharp.Math) type. And I get that error: Exception Details: System.Runtime.Serialization.SerializationException: Type 'Microsoft.FSharp.Math.Instances+FloatNumerics@115' with data contract name 'Instances.FloatNumerics_x0040_115:http://schemas.datacontract.org/2004/07/Microsoft.FSharp.Math' is not expected. Add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer. I have tried to put KnownType attribute and some other stuff, but nothing helps! Could someone know the answer? This is the code I use: // [< KnownType( typeof<vector> ) >] type MyType = vector let public writeTest = let aaa = vector [1.1;2.2] let serializer = new DataContractJsonSerializer( typeof<MyType> ) let writer = new StreamWriter( @"c:\test.txt" ) serializer.WriteObject(writer.BaseStream, aaa) writer.Close()

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  • What wording in the C++ standard allows static_cast<non-void-type*>(malloc(N)); to work?

    - by ben
    As far as I understand the wording in 5.2.9 Static cast, the only time the result of a void*-to-object-pointer conversion is allowed is when the void* was a result of the inverse conversion in the first place. Throughout the standard there is a bunch of references to the representation of a pointer, and the representation of a void pointer being the same as that of a char pointer, and so on, but it never seems to explicitly say that casting an arbitrary void pointer yields a pointer to the same location in memory, with a different type, much like type-punning is undefined where not punning back to an object's actual type. So while malloc clearly returns the address of suitable memory and so on, there does not seem to be any way to actually make use of it, portably, as far as I have seen.

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  • When does a const return type interfere with template instantiation?

    - by Rimo
    From Herb Sutter's GotW #6 Return-by-value should normally be const for non-builtin return types. ... Note: Lakos (pg. 618) argues against returning const value, and notes that it is redundant for builtins anyway (for example, returning "const int"), which he notes may interfere with template instantiation. While Sutter seems to disagree on whether to return a const value or non-const value when returning an object of a non-built type by value with Lakos, he generally agrees that returning a const value of a built-in type (e.g const int) is not a good idea. While I understand why that is useless because the return value cannot be modified as it is an rvalue, I cannot find an example of how that might interfere with template instantiation. Please give me an example of how having a const qualifier for a return type might interfere with template instantiation.

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  • why do we have to send the const " type " reference instead of just the types name to the constructo

    - by hamza
    i m trying to make a simple program ( & yes , it is a homework ) that can generate Dates , & like most of normal people : i made my Class attributes private , i tried to send the same type that i m working on to the constructor but the complier have not accept it , i did some research & i found out that in cases like that people generously send a const "type" reference to the constructor witch meant to me that have not understand OOP well so why do we have to send the const " type " reference instead of just the types name to the constructor ? & please give me some links or websites for beginners PS : sorry for my English

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  • C# - Custom Attributes - Setting an attribute property to the type of the decorated class.

    - by cmaduro
    Is it possible to get the decorated class' type inside of the custom attribute's class? For example: [MetadataAttribute] [AttributeUsage(AttributeTargets.Class | AttributeTargets.Property, AllowMultiple = false)] public class ViewAttribute : ExportAttribute { public object TargetRegion { get; set; } public Type ViewModel { get; set; } public Type Module { get; set; } public ViewAttribute() : base(typeof(UserControl)) { Module = GetDecoratedClassType(); //I need this method } } In the following example GetDecoratedClassType() would return HomeView [View] HomeView MyHomeView { get; set; }

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  • Using .Net, how can I determine if a type is a Numeric ValueType?

    - by Nescio
    Title says it all... But here's an example: Dim desiredType as Type if IsNumeric(desiredType) then ... EDIT: I only know the Type, not the Value as a string. Ok, so unfortunately I have to cycle through the TypeCode. But this is a nice way to do it: if ((desiredType.IsArray)) return 0; switch (Type.GetTypeCode(desiredType)) { case 3: case 6: case 7: case 9: case 11: case 13: case 14: case 15: return 1; } ;return 0;

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  • What is the 'noreq' Filter Type an Alias for?

    - by Alan Storm
    I'm looking in to Magento's filtering options (Ecommerce System and PHP Framekwork with an expansive ORM system). Specifically the addFieldToFilter method. In this method, you specify a SQLish filter by passing in a single element array, with the key indicating the type of filter. For example, array('eq'=>'bar') //eq means equal array('neq'=>'bar') //neq means not equal would each give you a where clause that looks like where field = 'bar'; where field != 'bar'; So, deep in the bowels of the source, I found a comparison type named 'moreq' that maps to a = comparison operator array('moreq'=>'27') where field >= 27 The weird thing is, there's already a 'gteq' comparision type array('gteq'=>'27') where field >= 27 So, my question is, what does moreq stand for? Is is some special SQL concept that's supported in other databases that the Magento guys wants to map to MySQL, or is it just "more required" and an example what happens when you're doing rapid agile and trying to maintain backwards compatibility.

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  • Which term to use when referring to functional data structures: persistent or immutable?

    - by Bob
    In the context of functional programming which is the correct term to use: persistent or immutable? When I Google "immutable data structures" I get a Wikipedia link to an article on "Persistent data structure" which even goes on to say: such data structures are effectively immutable Which further confuses things for me. Do functional programs rely on persistent data structures or immutable data structures? Or are they always the same thing?

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  • How can I abstract out the core functionality of several Rails applications?

    - by hornairs
    I'd like to develop a number of non-trivial Rails applications which all implement a core set of functionality but each have certain particular customizations, extensions, and aesthetic differences. How can I pull the core functionality (models, controllers, helpers, support classes, tests) common to all these systems out in such a way that updating the core will benefit every application based upon it? I've seen Rails Engines but they seem to be too detached, almost too abstracted to be built upon. I can seem them being useful for adding one component to an existing app, for example bolting on a blog engine to your existing e-commerce site. Since engines seem to be mostly self contained, it seems difficult and inconvenient to override their functionality and views while keeping DRY. I've also considered abstracting the code into a gem, but this seems a little odd. Do I make the gem depend on the Rails gems, and the define models & controllers inside it, and then subclass them in my various applications? Or do I define many modules inside the gem that I include in the different spots inside my various applications? How do I test the gem and then test the set of customizations and overridden functionality on top of it? I'm also concerned with how I'll develop the gem and the Rails apps in tandem, can I vendor a git repository of the gem into the app and push from that so I don't have to build a new gem every iteration? Also, are there private gem hosts/can I set my own gem source up? Also, any general suggestions for this kind of undertaking? Abstraction paradigms to adhere to? Required reading? Comments from the wise who have done this before? Thanks!

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  • Is it possible to override a property and return a derived type in VB.NET?

    - by Casey
    Consider the following classes representing an Ordering system: Public Class OrderBase Public MustOverride Property OrderItem() as OrderItemBase End Class Public Class OrderItemBase End Class Now, suppose we want to extend these classes to a more specific set of order classes, keeping the aggregate nature of OrderBase: Public Class WebOrder Inherits OrderBase Public Overrides Property OrderItem() as WebOrderItem End Property End Class Public Class WebOrderItem Inherits OrderItemBase End Class The Overriden property in the WebOrder class will cause an error stating that the return type is different from that defined in OrderBase... however, the return type is a subclass of the type defined in OrderBase. Why won't VB allow this?

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  • Why does "xsd:date" of XML Schema Type mapped "javax.xml.datatype.XMLGregorianCalendar" When Schema-to-Java Mapping of JAXB does.

    - by Take
    I don't know why does "xsd:date" of XML Schema Type mapped "javax.xml.datatype.XMLGregorianCalendar" When Schema-to-Java Mapping of JAXB does. Why does "xsd:date" of XML Schema Type mapped "java.util.Date" ? I guess that JAXB intentionally does its mapping. I want to know that reason if any. And if exists it, how to change "xsd:date" of XML Schema Type to "java.util.Date" of Java class without using annotation(ex.@XmlJavaTypeAdapter). I want to do mashalling and unmarshalling without all annotations.

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  • How do you resolve the common naming collision between type and object?

    - by Catskul
    Since the standard c# convention is to capitalize the first letter of public properties, the old c++ convention of initial capital for type names, and initial lowercase for non-type names does not prevent the classic name collision where the most obvious object name matches the type name: class FooManager { public BarManager BarManager { get; set; } // Feels very wrong. // Recommended naming convention? public int DoIt() { // 1st and 2nd Bar Manager are different symbols return BarManager.Blarb + BarManager.StaticBlarb; } } class BarManager { public int Blarb { get; set; } public static int StaticBlarb { get; set; } } It seems to compile, but feels so wrong. Is there a recommend naming convention to avoid this?

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  • How to save derived type (TPT) in Entity Framework?

    - by Peter Stegnar
    I have problems with saving derived type (TPT) with Entity Framework to database. Let's say I have base entity Animal and derived type Dog. I want to save Dog entity. I thought that I could do it like contex.AddToDogs(), but contex contain only base entity - Animal. So I can only save Animal object - contex.AddToAnimals(). I have also tried with contex.AddObject("Animals", dogInstance), but I get the following error: The member with identity 'NavigationProperty' does not exist in the metadata collection. But I have add EntityReference to the "NavigationProperty". So how to save derived type in EF?

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  • How to invoke static method in C#4.0 with dynamic type?

    - by Morgan Cheng
    In C#4.0, we have dynamic type, but how to invoke static method of dynamic type object? Below code will generate exception at run time. class Foo { public static int Sum(int x, int y) { return x + y; } } class Program { static void Main(string[] args) { dynamic d = new Foo(); Console.WriteLine(d.Sum(1, 3)); } } IMHO, dynamic is invented to bridge C# and other programming language. There is some other language (e.g. Java) allows to invoke static method through object instead of type. BTW, The introduction of C#4.0 is not so impressive compared to C#3.0.

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  • Problem with receiving data form serial port in c#?

    - by moon
    hello i have problem with receiving data from serial port in c# in am inserting a new line operator at the end of data buffer. then i send this data buffer on serial port, after this my c# GUI receiver will take this data via Readline() function but it always give me raw data not the actual one how to resolve this problem.

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  • How to track dealloc of an abstract object class (NSMutable...)

    - by Thomas Tempelmann
    I have a bug in my code caused by a premature freeing of a ObjC object. I seem not to be able to find it by just looking at my code. There's usually a simple trick to track the dealloc to any class: Implement dealloc, and set a breakpoint. This even usually works with standard objects, by subclassing them and making sure I instantiate the subclass instead of the standard class. However, this does not seem to work with NSMutableArray, and probably neither with similar NSMutable... classes. Some explanations for this can be found here: link text Any other ideas how to track the dealloc invocation of a particular class or object so that I can see the call stack? It's probably possible with DTrace. Any pointers without having to read the entire dtrace docs first?

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  • What's the deal with all of the abstract stuff?

    - by JustVenting
    I see a lot of talk about MVVM, MVC, Design Patterns etc... You know, some guy has a blog, and he spent the last six months learning about one these things and desiging a program centered around that concept and then he goes on and on about it like its better than sliced bread. I read all of this crap and I wonder, whatever happened to simple logical programming? Not self-absorbed huge frameworks of design patterns and mvc and whatever else you can think of... just simple linear programming, perhaps a few classes to encapsulate things here and there.

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  • How to model and handle presentation DTO's to abstract from complicated domain model?

    - by arrages
    Hi I am developing an application that needs to work with a complex domain model using Hibernate. This application uses Spring MVC and using the domain objects in the presentation layer is very messy so I think I should use DTO's that go to and from my service layer so that these match what I need in my views. Now lets assume I have a CarLease entity whose properties are not simple java primitives but it's composed with other entities like Make, Model, etc public class CarLease { private Make make; Private Model model; . . . } most properties are in this fashion and they are selectable using drop down selects on the jsp view, each will post back an ID to the controller. Now considering some standard use cases: create, edit, display How would you go about modeling the presentation DTO's to be used as form backing objects and communication between presentation and service layers?? Would you create a different DTO for each case (create, edit, display), would you make DTO's for the complex attributes? if so where would you translate the ID to entity? how and where would you handle validation, DTO/Domain assembly, what would you return from service layer methods? (create, edit, get) As you can see, I now I will benefit by separating my view from the domain objects (very complex with lots of stuff I don't need.) but I am having a hard time finding any real world examples and best practices for this. I need some architecture guidance from top to bottom, please keep in mind I will use Spring MVC in case that may leverage on your anwser. thanks in advance.

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  • How can I receive the "scroll box" type scroll events from a DataGridView?

    - by Simon
    I have a DataGridView, and I'm listening to its Scroll event. This gives me a ScrollEventArgs object whose Type member is supposed to tell me the type of scroll event that has occurred. On the MSDN documentation page it says I should be able to detect movement of the scroll box by listening for events with types ThumbPosition, ThumbTrack, First, Last and EndScroll. However, when I drag the scroll box, I only get events of type LargeDecrement and LargeIncrement. How do I get access to the ThumbPosition, ThumbTrack, First, Last and EndScroll events?

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  • Dynamic parameters for XSLT 2.0 group-by

    - by Ophileon
    I got this input <?xml version="1.0" encoding="UTF-8"?> <result> <datapoint poiid="2492" period="2004" value="1240"/> <datapoint poiid="2492" period="2005" value="1290"/> <datapoint poiid="2492" period="2006" value="1280"/> <datapoint poiid="2492" period="2007" value="1320"/> <datapoint poiid="2492" period="2008" value="1330"/> <datapoint poiid="2492" period="2009" value="1340"/> <datapoint poiid="2492" period="2010" value="1340"/> <datapoint poiid="2492" period="2011" value="1335"/> <datapoint poiid="2493" period="2004" value="1120"/> <datapoint poiid="2493" period="2005" value="1120"/> <datapoint poiid="2493" period="2006" value="1100"/> <datapoint poiid="2493" period="2007" value="1100"/> <datapoint poiid="2493" period="2008" value="1100"/> <datapoint poiid="2493" period="2009" value="1110"/> <datapoint poiid="2493" period="2010" value="1105"/> <datapoint poiid="2493" period="2011" value="1105"/> </result> and I use this xslt 2.0 <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="xs" version="2.0"> <xsl:output method="xml" indent="yes"/> <xsl:template match="result"> <xsl:for-each-group select="datapoint" group-by="@poiid"> <node type="poiid" id="{@poiid}"> <xsl:for-each select="current-group()"> <node type="period" id="{@period}" value="{@value}"/> </xsl:for-each> </node> </xsl:for-each-group> </xsl:template> </xsl:stylesheet> to convert it into <?xml version="1.0" encoding="UTF-8"?> <node type="poiid" id="2492"> <node type="period" id="2004" value="1240"/> <node type="period" id="2005" value="1290"/> <node type="period" id="2006" value="1280"/> <node type="period" id="2007" value="1320"/> <node type="period" id="2008" value="1330"/> <node type="period" id="2009" value="1340"/> <node type="period" id="2010" value="1340"/> <node type="period" id="2011" value="1335"/> </node> <node type="poiid" id="2493"> <node type="period" id="2004" value="1120"/> <node type="period" id="2005" value="1120"/> <node type="period" id="2006" value="1100"/> <node type="period" id="2007" value="1100"/> <node type="period" id="2008" value="1100"/> <node type="period" id="2009" value="1110"/> <node type="period" id="2010" value="1105"/> <node type="period" id="2011" value="1105"/> </node> Works smoothly. Where I got stuck is when I tried to make it more dynamic. The real life input has 6 attributes for each datapoint instead of 3, and the usecase requires the possibility to set the grouping parameters dynamically. I tried using parameters <xsl:param name="k1" select="'poiid'"/> <xsl:param name="k2" select="'period'"/> but passing them to the rest of the xslt is something that I can't get right. The code below doesn't work, but clarifies hopefully, what I'm looking for. <xsl:template match="result"> <xsl:for-each-group select="datapoint" group-by="@{$k1}"> <node type="{$k1}" id="@{$k1}"> <xsl:for-each select="current-group()"> <node type="{$k2}" id="@{$k2}" value="{@value}"/> </xsl:for-each> </node> </xsl:for-each-group> </xsl:template> Any help appreciated..

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  • How can I check the type of an object against a list of types?

    - by RookieRick
    Given a collection IEnumerable<Type> supportedTypes What's the best way to check whether a given object is one of those types (or a derived type)? My first instinct was to do something like: // object target is a parameter passed to the method in which I'm doing this. if (supportedTypes.Count( supportedType => target is supportedType ) > 0) { // Yay my object is of a supported type!!! } ..but that doesn't seem to be working. Can I not use the "is" keyword in a lambda expression like this?

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  • How to write function where argument is type but not typed value?

    - by ssp
    I want to convert a string representations of few dozen enum types to enum values. It's easy to convert string to concrete type: Enum.Parse(typeof<FontStyle>,"Bold") |> unbox<FontStyle> but for now i want to write function where type and string are parameters. The best one i can write is: > let s2e (_: 'a) s = Enum.Parse(typeof<'a>,s) |> unbox<'a>;; val s2e : 'a -> string -> 'a > s2e FontStyle.Regular "Bold";; val it : FontStyle = Bold Is there any option to write something like this but with type itself as first argument?

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  • Why can't I set attribute "TYPE" of LI element in IE?

    - by Petr Urban
    Hello, I've just come to an unusual beghavior of Internet Explorer IE (v8.0.6001.18904). When I try to set "type" attribute of any <LI> element, it will result into error. I used jQuery (v1.32): $("<li>").attr("type", "test"); The same thing works for DIV. LI element does not seem to have "type" attribute reserved by HTML or XHTML definitions. It also might be jQuery issue. Solution is simple - just use another attribute name :-) But is there someone out there who knows WHY does this error occur? Could it happen with another attribute names? Why the error comes with LI element only?

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  • What will happen if I change the type of a column from int to year?

    - by MachinationX
    I have a table in MySQL 4.0 which currently has a year field as a smallint(6) type. What will happen if I convert it directly to a Year type with a query like the following: ALTER TABLE t MODIFY y YEAR(4) NOT NULL DEFAULT CURRENT_TIMESTAMP; When the current members of column y have values like 2010? I assume that because the year type is technically values from 1-255, values above that will be truncated or broken. So if MySQL isn't smart enough to realize that 2010(int) = 110(year), what would be the simplest query or queries to convert the values? Thanks for your help!

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