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  • Linq Query - Average Time (DateTime data types)

    - by Jade
    I have a database that has the following records in a DateTime field: 2012-04-13 08:31:00.000 2012-04-12 07:53:00.000 2012-04-11 07:59:00.000 2012-04-10 08:16:00.000 2012-04-09 15:11:00.000 2012-04-08 08:28:00.000 2012-04-06 08:26:00.000 I want to run a linq to sql query to get the average time from the records above. I tried the following: (From o In MYDATA Select o.SleepTo).Average() Since "SleepTo" is a datetime field I get an error on Average(). If I was trying to get the average of say an integer, the above linq query works. What do I need to do to get it to work for datetimes?

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  • C++ Template problem adding two data types

    - by Sara
    I have a template class with an overloaded + operator. This is working fine when I am adding two ints or two doubles. How do I get it to add and int and a double and return the double? template <class T> class TemplateTest { private: T x; public: TemplateTest<T> operator+(const TemplateTest<T>& t1)const { return TemplateTest<T>(x + t1.x); } } in my main function i have void main() { TemplateTest intTt1 = TemplateTest<int>(2); TemplateTest intTt2 = TemplateTest<int>(4); TemplateTest doubleTt1 = TemplateTest<double>(2.1d); TemplateTest doubleTt2 = TemplateTest<double>(2.5d); std::cout << intTt1 + intTt2 << /n; std::cout << doubleTt1 + doubleTt2 << /n; } I want to be able to also do this std::cout << doubleTt1 + intTt2 << /n;

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  • Ideal HTTP cache control headers for different types of resources

    - by chris_l
    I want to find a minimal set of headers, that work with "all" caches and browsers (also when using HTTPS!) On my (GWT-based) web site, I'll have three kinds of resources: 1. Forever cacheable (public / equal for all users) These files don't ever change, and they get a filename based on the MD5 of their contents (this is GWT's approach). They should get cached as much as possible, even when using HTTPS (so I assume, I should set Cache-Control: public, especially for Firefox?) 2. Changing for every new version of the site (public / equal for all users) These files can be cached, but probably need to be revalidated every time. 3. Individual for each request (private / user specific) These resources (e. g. JSON responses) should never be cached unencrypted to disk under no circumstances. (Maybe I'll have a few specific requests that could be cached.) I have a general idea on which headers I would probably use for each type, but there's always something I could be missing.

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  • Implicit conversion between Scala collection types

    - by ebruchez
    I would like to implicitly convert between the Scala XML Elem object and another representation of an XML element, in my case dom4j Element. I wrote the following implicit conversions: implicit def elemToElement(e: Elem): Element = ... do conversion here ... implicit def elementToElem(e: Element): Elem = ... do conversion here ... So far so good, this works. Now I also need collections of said elements to convert both ways. First, do I absolutely need to write additional conversion methods? Things didn't seem to work if I didn't. I tried to write the following: implicit def elemTToElementT(t: Traversable[Elem]) = t map (elemToElement(_)) implicit def elementTToElemT(t: Traversable[Element]) = t map (elementToElem(_)) This doesn't look too ideal because if the conversion method takes a Traversable, then it also returns a Traversable. If I pass a List, I also get a Traversable out. So I assume the conversion should be parametrized somehow. So what's the standard way of writing these conversions in order to be as generic as possible?

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  • Using groovy ws with enum types?

    - by Jared
    I'm trying to use groovy ws to call a webservice. One of the properties of the generated class is it's self a class with an enum type. Although the debug messages show that the com.test.FinalActionType is created at runtime when the WSDL is read I can't create an instance of it using code like proxy.create("com.test.FinalActionType") When I try and assign a string to my class uin place of an instance of FinalActionType groovy is not able to do the conversion. How can I get an instance of this class to use in a webservice call? I've pasted the important part of the WSDL below. <xsd:simpleType name="FinalActionType"> <xsd:restriction base="xsd:string"> <xsd:enumeration value="stop"/> <xsd:enumeration value="quit"/> <xsd:enumeration value="continue"/> <xsd:whiteSpace value="collapse"/> </xsd:restriction> </xsd:simpleType>

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  • Control XML serialization of generic types

    - by Luca
    I'm investigating about XML serialization, and since I use lot of dictionary, I would like to serialize them as well. I found the following solution for that (I'm quite proud of it! :) ). [XmlInclude(typeof(Foo))] public class XmlDictionary<TKey, TValue> { /// <summary> /// Key/value pair. /// </summary> public struct DictionaryItem { /// <summary> /// Dictionary item key. /// </summary> public TKey Key; /// <summary> /// Dictionary item value. /// </summary> public TValue Value; } /// <summary> /// Dictionary items. /// </summary> public DictionaryItem[] Items { get { List<DictionaryItem> items = new List<DictionaryItem>(ItemsDictionary.Count); foreach (KeyValuePair<TKey, TValue> pair in ItemsDictionary) { DictionaryItem item; item.Key = pair.Key; item.Value = pair.Value; items.Add(item); } return (items.ToArray()); } set { ItemsDictionary = new Dictionary<TKey,TValue>(); foreach (DictionaryItem item in value) ItemsDictionary.Add(item.Key, item.Value); } } /// <summary> /// Indexer base on dictionary key. /// </summary> /// <param name="key"></param> /// <returns></returns> public TValue this[TKey key] { get { return (ItemsDictionary[key]); } set { Debug.Assert(value != null); ItemsDictionary[key] = value; } } /// <summary> /// Delegate for get key from a dictionary value. /// </summary> /// <param name="value"></param> /// <returns></returns> public delegate TKey GetItemKeyDelegate(TValue value); /// <summary> /// Add a range of values automatically determining the associated keys. /// </summary> /// <param name="values"></param> /// <param name="keygen"></param> public void AddRange(IEnumerable<TValue> values, GetItemKeyDelegate keygen) { foreach (TValue v in values) ItemsDictionary.Add(keygen(v), v); } /// <summary> /// Items dictionary. /// </summary> [XmlIgnore] public Dictionary<TKey, TValue> ItemsDictionary = new Dictionary<TKey,TValue>(); } The classes deriving from this class are serialized in the following way: <XmlProcessList xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Items> <DictionaryItemOfInt32Foo> <Key/> <Value/> </DictionaryItemOfInt32XmlProcess> <Items> This give me a good solution, but: How can I control the name of the element DictionaryItemOfInt32Foo What happens if I define a Dictionary<FooInt32, Int32> and I have the classes Foo and FooInt32? Is it possible to optimize the class above? THank you very much!

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  • Tools to thumbnail multiple extension types

    - by Joomala
    My requirements are to be able to thumbnail the major image and file extensions: doc(x), txt, xls(x), pdf, rte, and as many others as possible. We have been hooking into Office extensions to do this in the past, but they are not really supported on Vista and Windows 7 operating systems. Are there any third party thumbnailing applications that you have had success implementing? Preferably ones that are easy to invoke from .Net

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  • Python: Using `copyreg` to define reducers for types that already have reducers

    - by cool-RR
    (Keep in mind I'm working in Python 3, so a solution needs to work in Python 3.) I would like to use the copyreg module to teach Python how to pickle functions. When I tried to do it, the _Pickler object would still try to pickle functions using the save_global function. (Which doesn't work for unbound methods, and that's the motivation for doing this.) It seems like _Pickler first tries to look in its own dispatch for the type of the object that you want to pickle before looking in copyreg.dispatch_table. I'm not sure if this is intentional. Is there any way for me to tell Python to pickle functions with the reducer that I provide?

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  • Deserialising Json to derived types in Asp.Net Web API

    - by IoChaos
    I'm calling a method of my WebAPI sending a json that I would like to match (or bind) with a model. In the controller I have a method like: public Result Post([ModelBinder(typeof(CustomModelBinder))]MyClass model); 'MyClass', wich is given as a parameter is an abstract class. I would like that at, depending of the type of json passed, the correct inherited class is instantiated. To achieve it, I'm trying to implement a custom binder. The problem is that (I don't know if it's very basic but I can't find anything) I don't know how to retrieve the raw Json (or better, some kind of serialization) that comes in the request. I see: actionContext.Request.Content But all methods are exposed as async. I don't know who this fits with passing the generate model to the controller method... Thanks a lot!

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  • Forcing entry of certain character types in UITextField

    - by cannyboy
    If I have a UITextField which the user is inputing a registration number, which has the format: 11-11-1111 (that is 2 digits, a dash, 2 digits, a dash, four digits) How do I force the user to enter this kind of data only... so they can't enter anything except 0-9 in the first character, and only '-' for the third character etc.

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  • StructureMap Open Generic Types

    - by Shane Fulmer
    I have the following classes: public interface IRenderer<T> { string Render(T obj); } public class Generic<T> { } public class SampleGenericRenderer<T> : IRenderer<Generic<T>> { public string Render(Generic<T> obj) { throw new NotImplementedException(); } } I would like to be able to call StructureMap with ObjectFactory.GetInstance<IRenderer<Generic<string>>>(); and receive SampleGenericRenderer<string>. I'm currently using the following registration and receiving this error when I call GetInstance. "Unable to cast object of type 'ConsoleApplication1.SampleGenericRenderer'1[ConsoleApplication1.Generic'1[System.String]]' to type 'ConsoleApplication1.IRenderer'1[ConsoleApplication1.Generic'1[System.String]]'." public class CoreRegistry : Registry { public CoreRegistry() { Scan(assemblyScanner => { assemblyScanner.AssemblyContainingType(typeof(IRenderer<>)); assemblyScanner.AddAllTypesOf(typeof(IRenderer<>)); assemblyScanner.ConnectImplementationsToTypesClosing(typeof(IRenderer<>)); }); } } Is there any way to configure StructureMap so that it creates SampleGenericRenderer<string> instead of SampleGenericRenderer<Generic<string>>?

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  • A better way of getting a data table with various column types into string array

    - by Vlad
    This should be an easy one, looks like I got myself too confused. I get a table from a database, data ranges from varchar to int to Null values. Cheap and dirty way of converting this into a tab-delimited file that I already have is this (shrunken to preserve space, ugliness is kept on par with original): da.Fill(dt) ' da - DataAdapter ' ' dt - DataTable ' Dim lColumns As Long = dt.Columns.Count Dim arrColumns(dt.Columns.Count) As String Dim arrData(dt.Columns.Count) As Object Dim j As Long = 0 Dim arrData(dt.Columns.Count) As Object For i = 0 To dt.Rows.Count - 1 arrData = dt.Rows(i).ItemArray() For j = 0 To arrData.GetUpperBound(0) - 1 arrColumns(j) = arrData(j).ToString Next wrtOutput.WriteLine(String.Join(strFieldDelimiter, arrColumns)) Array.Clear(arrColumns, 0, arrColumns.GetLength(0)) Array.Clear(arrData, 0, arrData.GetLength(0)) Next Not only this is ugly and inefficient, it is also getting on my nerves. Besides, I want, if possible, to avoid the infamous double-loop through the table. I would really appreciate a clean and safe way of rewriting this piece. I like the approach that is used here - especially that is trying to solve the same problem that I have, but it crashes on me when I apply it to my case directly.

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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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  • problems with Haskell's Number Types

    - by mindeavor.
    I have the following haskell code: fac n = product [1..n] taylor3s w0 f f' f'' t h = w1 : taylor3s w1 f f' f'' (t+h) h where hp i = h^i / fac i w1 = w0 + (hp 1) * f t w0 + (hp 2) * f' t w0 + (hp 3) * f'' t w0 taylor_results = take 4 $ taylor3s 1 f f' f'' 1 0.25 where f t x = t^4 - 4*x/t f' t x = 4*t^3 - 4*(f t x)/t + 4*x/t^2 f'' t x = 12*t^2 - 4*(f' t x)/t + 8*(f t x)/t^2 - 8*x/t^3 taylor_results is supposed to be a use case of taylor3s. However, there is something wrong with the number type inferencing. When I try to compile, this is the error I get: practice.hs:93:26: Ambiguous type variable `a' in the constraints: `Integral a' arising from a use of `taylor3s' at practice.hs:93:26-51 `Fractional a' arising from a use of `f' at practice.hs:93:37 Possible cause: the monomorphism restriction applied to the following: taylor_results :: [a] (bound at practice.hs:93:0) Probable fix: give these definition(s) an explicit type signature or use -XNoMonomorphismRestriction Can someone help me with understanding what the problem is?

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  • C# underlying types of enums

    - by Marlon
    What is the point of having enum SomeEnum : byte // <---- { SomeValue = 0x01, ... } when you have to make a cast just to assign it to the same type of variable as the enums underlying type? byte b = (byte)SomeEnum.SomeValue;

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  • File System Types in .Net

    - by Avi
    I don't get the abstractions and the terminology :-( For example, DirectoryInfo.FullName is defined as the full path of the directory or file, but it's a string! So is DirectoryInfo.Name, FileInfo.FullName, Path.GetDirectoyName and so on. This means that in .Net there is no "depth" (or "meat" - my English isn't so good) for the file system objects. There's no protection from a type system. I can't, for example, define two Path objects and ask if one of them is "above" the other - I have to manipulate the strings. I can't differentiate between a Path that identifies a directory and a path that identifies a file. I can't do anything!-( Just manipulate strings. Is this correct (or am I simply missing something). If correct, are there any alternatives?

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  • Validating primitive types in ASP.NET MVC

    - by Alex
    I've implemented the following classes to validate data public abstract class Validated { public bool IsValid { get { return (GetRuleViolations().Count() == 0); } } public abstract IEnumerable<RuleViolation> GetRuleViolations(); } public partial class User: Validated { public override IEnumerable<RuleViolation> GetRuleViolations() { if (this.Age < 1) yield return new RuleViolation("Age can't be less than 1"); } } It works great! When the form is submitted I just do if (user.IsValid == false) blah... But I still need to validate that the Age is an integer int a = 0; if (!int.TryParse(age, out a)) { error = "Not integer"; // ... } How can I move this to my model?

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  • Mapping integers to types using C++ template fails in a specific case

    - by Shailesh Kumar
    I am attempting to compile the following template based code in VC++ 2005. #include <iostream> using namespace std; /* * T is a template which maps an integer to a specific type. * The mapping happens through partial template specialization. * In the following T<1> is mapped to char, T<2> is mapped to long * and T<3> is mapped to float using partial template specializations */ template <int x> struct T { public: }; template<> struct T<1> { public: typedef char xType; }; template<> struct T<2> { public: typedef long xType; }; template<> struct T<3> { public: typedef float xType; }; // We can easily access the specific xType for a specific T<N> typedef T<3>::xType x3Type; /*! * In the following we are attempting to use T<N> inside another * template class T2<R> */ template<int r> struct T2 { //We can map T<r> to some other type T3 typedef T<r> T3; // The following line fails typedef T3::xType xType; }; int main() { T<1>::xType a1; cout << typeid(a1).name() << endl; T<2>::xType a2; cout << typeid(a2).name() << endl; T<3>::xType a3; cout << typeid(a3).name() << endl; return 0; } There is a particular line in the code which doesn't compile: typedef T3::xType xType; If I remove this line, compilation goes fine and the result is: char long float If I retain this line, compilation errors are observed. main.cpp(53) : warning C4346: 'T<x>::xType' : dependent name is not a type prefix with 'typename' to indicate a type main.cpp(54) : see reference to class template instantiation 'T2<r>' being compiled main.cpp(53) : error C2146: syntax error : missing ';' before identifier 'xType' main.cpp(53) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int I am not able to figure out how to make sure that T::xType can be treated as a type inside the T2 template. Any help is highly appreciated.

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  • iPhone: Types of persistent store

    - by Lisa
    Hi, I would like to know which type of persistent store would be most appropriate in what situations, like how can I decide where to use core data, property list or archives for my iPhone application. Thanks

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