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  • WPF data binding issue .

    - by Praveen
    Hi All, I have a wpf app and there i simply have a dock panel and inside dock panel i have a textblock. I want to bind the text property of textblock to my custom objects property but that' not working. I think i am missing something here but don't know what. Here is the code snippet. <TextBlock Text="{Binding Source=myDataSource, Path=ColorName}"/> </DockPanel> My custom class. class MyData { public string ColorName { get; set; } } and main window constructor.. public partial class MainWindow : Window { MyData myDataSource; public MainWindow() { InitializeComponent(); myDataSource = new MyData { ColorName = "Red" }; } }

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  • Tie destruction of an object (sealed) to destruction of an unmanaged buffer

    - by testtestSO
    I'll explain my situation first: I'm interested of using the Bitmap constructor that takes scan0, stride and format, because I'm decoding tiled images and I'd like to choose my own stride so I can decode the tiles without caring about the bounds in the decoder part. Anyway, the problem is that the documentation says: The caller is responsible for allocating and freeing the block of memory specified by the scan0 parameter. However, the memory should not be released until the related Bitmap is released. I can't release the buffer easily, because the Bitmap is then passed to another class that will eventually destroy it and I don't have control over it. Is there some way (hacky, I know) to tell the GC to also release my buffer when the Bitmap is destroyed? (Also, any alternative solution is welcome).

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  • Silently binding a variable instance to a class in C++?

    - by gct
    So I've got a plugin-based system I'm writing. Users can create a child class of a Plugin class and then it will be loaded at runtime and integrated with the rest of the system. When a Plugin is run from the system, it's run in the context of a group of plugins, which I call a Session. My problem is that inside the user plugins, two streaming classes called pf_ostream and pf_istream can be used to read/write data to the system. I'd like to bind the plugin instance's session variable to pf_ostream and pf_istream somehow so that when the user instantiates those classes, it's already bound to the session for them (basically I don't want them to see the session internals) I could just do this with a macro, wrapping a call to the constructor like: #define MAKE_OSTREAM = pf_ostream_int(this->session) But I thought there might be a better way. I looked at using a nested class inside Plugin wrapping pf_ostream but it appears nested classes don't get access to the enclosing classes variables in a closure sort of way. Does anyone know of a neat way to do this?

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  • C++11 initialize array with uniform value in constexpr function

    - by marack
    I have a class template which builds a simple array based on the template parameters as one of its members. I need to be able to initialize every element in the array to a single value in one of the constructors. Unfortunately this constructor must be constexpr. The relevant part boils down to: template <typename T, size_t N> class foo { T data[N]; constexpr foo(T val) { // initialize data with N copies of val } }; Using std::fill or a loop is incompatible with the constexpr requirement. Initializing with : data{val} only sets the first element of the array and zero-initializes the remainder. How can this be achieved? I feel like there should be a solution with variadic templates and tuples etc...

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  • C# language questions

    - by Water Cooler v2
    1) What is int? Is it any different from the struct System.Int32? I understand that the former is a C# alias (typedef or #define equivalant) for the CLR type System.Int32. Is this understanding correct? 2) When we say: IComparable x = 10; Is that like saying: IComparable x = new System.Int32(); But we can't new a struct, right? or in C like syntax: struct System.In32 *x; x=>someThing = 10; 3) What is String with a capitalized S? I see in Reflector that it is the sealed String class, which, of course, is a reference type, unlike the System.Int32 above, which is a value type. What is string, with an uncapitalized s, though? Is that also the C# alias for this class? Why can I not see the alias definitions in Reflector? 4) Try to follow me down this subtle train of thought, if you please. We know that a storage location of a particular type can only access properties and members on its interface. That means: Person p = new Customer(); p.Name = "Water Cooler v2"; // legal because as Name is defined on Person. but // illegal without an explicit cast even though the backing // store is a Customer, the storage location is of type // Person, which doesn't support the member/method being // accessed/called. p.GetTotalValueOfOrdersMade(); Now, with that inference, consider this scenario: int i = 10; // obvious System.object defines no member to // store an integer value or any other value in. // So, my question really is, when the integer is // boxed, what is the *type* it is actually boxed to. // In other words, what is the type that forms the // backing store on the heap, for this operation? object x = i;

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  • How do I convert c struct from dll to C#

    - by poco
    I am converting a application from c++ to C# and have a question about the proper way to handle importing structs. I am attempting to convert a struct from a c dll into c# The struct in c looks like this typedef struct card_info { ushort r; ushort s; enum_a a; usinged long ul; ushort n; ushort* b; ushort id; } CARD_INFO; when i use [StructLayout(LayoutKind.Sequentaial)] the size of the array is 20 bytes in c#. However, if take a look at my working c++ code it is 24 bytes. I changed my c# to look like this: [StructLayout(LayoutKind.Explicit)] public struct CardInfo { [FieldOffset(0) public ushort r; [FieldOffset(2) public ushort s; [FieldOffset(4) public EnumA a; [FieldOffset(8) public ushort ul; [FieldOffset(12) public ushort n; [FieldOffset(16) public UInt32 b; [FieldOffset(20) public ushort id; } This seems to compile but I'm not convinced this is the correct way to go about doing this. Please let me know if this is correct or if there is a better way. Thanks

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  • jUnit same exception in different cases

    - by coubeatczech
    Hi, I'm writing a jUnit test for a constructor that parses a String and then check numerous things. When there's wrong data, for every thing, some IllegalArgumentException with different message is thrown. So I would like to write tests for it, but how can i recognize what error was thrown? This is how can I do it: @Test(expected=IllegalArgumentException.class) public void testRodneCisloRok(){ new RodneCislo("891415",dopocitej("891415")); } and this is how I would like to be, but I don't know if it is possible to write it somehow: @Test(expected=IllegalArgumentException.class("error1")) public void testRodneCisloRok(){ new RodneCislo("891415",dopocitej("891415")); }

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  • Best way to create a Unique ID field for an enum

    - by jax
    What is the best way to get a Unique ID from an ENUM that will stay consistent between repeated execution of the program? Currently I am doing this manually by passing an ID to the enum constructor. I don't really want to do this is I can help it. Another option would be to use a static field that gets incremented for each enum value. The problem is that if later I decide to move the enum fields around or delete some this will cause problems with my program as the ID will be saved into user preferences. The ID can be any basic type or a String.

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  • Can't get a List(Of <my class>) from a Dictionary in .NET?

    - by magsto
    I have a Dictionary with key of type UInteger and the value is List(Of Session) where the (Public) class Session contains a couple of variables and a constructor (Public Sub New(...)). Some of the variables in my Session class is: Private count As Integer Private StartDate As Date Private Values As List(Of Integer) and a couple of methods like: Friend Sub Counter(ByVal c as Integer) count += c End Sub There is no problem to add values to the Dictionary: Dim Sessions As New List(Of Session) Dim dict As New Dictionary(Of Integer, Sessions) then some code to fill up a couple of Session objects in Sessions (not shown here) and then: dict.Add(17, Sessions) 'No problem Sessions.Clear() Sessions = dict(17) 'This doesn't return anything! The Sessions object is empty even if the code doesn't returned any error. Is my class Session to compex to be stored in a Dictionary?

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  • Pattern matching against Scala Map type

    - by Tom Morris
    Imagine I have a Map[String, String] in Scala. I want to match against the full set of key–value pairings in the map. Something like this ought to be possible val record = Map("amenity" -> "restaurant", "cuisine" -> "chinese", "name" -> "Golden Palace") record match { case Map("amenity" -> "restaurant", "cuisine" -> "chinese") => "a Chinese restaurant" case Map("amenity" -> "restaurant", "cuisine" -> "italian") => "an Italian restaurant" case Map("amenity" -> "restaurant") => "some other restaurant" case _ => "something else entirely" } The compiler complains thulsy: error: value Map is not a case class constructor, nor does it have an unapply/unapplySeq method What currently is the best way to pattern match for key–value combinations in a Map?

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  • VB Change Calulator

    - by BlueBeast
    I am creating a VB 2008 change calculator as an assignment. The program is to use the amount paid - the amount due to calculate the total.(this is working fine). After that, it is to break that amount down into dollars, quarters, dimes, nickels, and pennies. The problem I am having is that sometimes the quantity of pennies, nickels or dimes will be a negative number. For example $2.99 = 3 Dollars and -1 Pennies. SOLVED Thanks to the responses, here is what I was able to make work with my limited knowledge. Option Explicit On Option Strict Off Option Infer Off Public Class frmMain Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click 'Clear boxes lblDollarsAmount.Text = String.Empty lblQuartersAmount.Text = String.Empty lblDimesAmount.Text = String.Empty lblNickelsAmount.Text = String.Empty lblPenniesAmount.Text = String.Empty txtOwed.Text = String.Empty txtPaid.Text = String.Empty lblAmountDue.Text = String.Empty txtOwed.Focus() End Sub Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click 'Close application' Me.Close() End Sub Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click ' Find Difference between Total Price and Total Received lblAmountDue.Text = Val(txtPaid.Text) - Val(txtOwed.Text) Dim intChangeAmount As Integer = lblAmountDue.Text * 100 'Declare Integers Dim intDollarsBack As Integer Dim intQuartersBack As Integer Dim intDimesBack As Integer Dim intNickelsBack As Integer Dim intPenniesBack As Integer ' Change Values Const intDollarValue As Integer = 100 Const intQuarterValue As Integer = 25 Const intDimeValue As Integer = 10 Const intNickelValue As Integer = 5 Const intPennyValue As Integer = 1 'Dollars intDollarsBack = CInt(Val(intChangeAmount \ intDollarValue)) intChangeAmount = intChangeAmount - Val(Val(intDollarsBack) * intDollarValue) lblDollarsAmount.Text = intDollarsBack.ToString 'Quarters intQuartersBack = CInt(Val(intChangeAmount \ intQuarterValue)) intChangeAmount = intChangeAmount - Val(Val(intQuartersBack) * intQuarterValue) lblQuartersAmount.Text = intQuartersBack.ToString 'Dimes intDimesBack = CInt(Val(intChangeAmount \ intDimeValue)) intChangeAmount = intChangeAmount - Val(Val(intDimesBack) * intDimeValue) lblDimesAmount.Text = intDimesBack.ToString 'Nickels intNickelsBack = CInt(Val(intChangeAmount \ intNickelValue)) intChangeAmount = intChangeAmount - Val(Val(intNickelsBack) * intNickelValue) lblNickelsAmount.Text = intNickelsBack.ToString 'Pennies intPenniesBack = CInt(Val(intChangeAmount \ intPennyValue)) intChangeAmount = intChangeAmount - Val(Val(intPenniesBack) * intPennyValue) lblPenniesAmount.Text = intPenniesBack.ToString End Sub End Class

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  • WPF/C# - Sometimes my dropdowns/datepickers will stop functioning?

    - by BlargINC
    Q: Where should I check to track this down? Issue: Opening a view model in my application sometimes makes dropdowns/datepickers nonfunctional. ie. dropdown won't drop and the datepicker calendar won't come up I suspect a binding issue but don't see one. Dropdowns have normal things like strings, numbers. One drop has a list of mini views. Datepickers are bound to nullable dates set in the constructor of the viewmodel. Note: These same things work in other viewmodels/views. I can paste code, I'm just not sure what code is relevant here. Thank you for helping me :)

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  • excel:mysql: rs.Update not working

    - by every_answer_gets_a_point
    i am updating a table using an ODBC connection from excel to mysql unfortunately the only column that gets updated is this one: .Fields("instrument") = "NA" where i am assigning variables to .Fields, it is putting NULL values!! what is going on here? here's the code Option Explicit Dim oConn As ADODB.Connection Private Sub ConnectDB() Set oConn = New ADODB.Connection oConn.Open "DRIVER={MySQL ODBC 5.1 Driver};" & _ "SERVER=localhost;" & _ "DATABASE=employees;" & _ "USER=root;" & _ "PASSWORD=pas;" & _ "Option=3" End Sub Function esc(txt As String) esc = Trim(Replace(txt, "'", "\'")) End Function Private Sub InsertData() Dim dpath, atime, rtime, lcalib, aname, rname, bstate, instrument As String Dim rs As ADODB.Recordset Set rs = New ADODB.Recordset ConnectDB With wsBooks rs.Open "batchinfo", oConn, adOpenKeyset, adLockOptimistic, adCmdTable Worksheets.Item("Report 1").Select dpath = Trim(Range("B2").Text) atime = Trim(Range("B3").Text) rtime = Trim(Range("B4").Text) lcalib = Trim(Range("B5").Text) aname = Trim(Range("B6").Text) rname = Trim(Range("B7").Text) bstate = Trim(Range("B8").Text) ' instrument = GetInstrFromXML(wbBook.FullName) With rs .AddNew ' create a new record ' add values to each field in the record .Fields("datapath") = dpath .Fields("analysistime") = atime .Fields("reporttime") = rtime .Fields("lastcalib") = lcalib .Fields("analystname") = aname .Fields("reportname") = rname .Fields("batchstate") = bstate .Fields("instrument") = "NA" .Update ' stores the new record End With ' get the last id Set rs = oConn.Execute("SELECT @@identity", , adCmdText) 'MsgBox capture_id rs.Close Set rs = Nothing End With End Sub

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  • How to set a value from another class

    - by Ram
    Its said that property should not be "Set" only and it should be "Get" as well. What should i do if I need to set value to a variable from some other class? The will keep changing so I cannot pass it through constructor. Shall I create a function for this as shown below? class A { public void SetValue() { b = new B(); b.SetTest(10); } } class B { int test; public void SetTest(int value) { test = value; } } What are the other alternatives?

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  • Why isn't the new() generic constraint satisfied by a class with optional parameters in the construc

    - by Joshua Flanagan
    The following code fails to compile, producing a "Widget must be a non-abstract type with a public parameterless constructor" error. I would think that the compiler has all of the information it needs. Is this a bug? An oversight? Or is there some scenario where this would not be valid? public class Factory<T> where T : new() { public T Build() { return new T(); } } public class Widget { public Widget(string name = "foo") { Name = name; } public string Name { get; set; } } public class Program { public static void Main() { var widget = new Widget(); // this is valid var factory = new Factory<Widget>(); // compiler error } }

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  • C++ syntax of constructors " 'Object1 a (1, Object1(2))''

    - by osgx
    Hello I have a such syntax in program class Object1 : BaseClass { BaseClass *link; int i; public: Object1(int a){i=a;} Object1(int a, Object1 /*place1*/ o) {i=a; link= &o;} }; int main(){ Object1 a(1, /*place2*/ Object1(2)); ... } What do I need in place1? I want to save a link (pointer) to the second object in the first object. Should I use in place1 reference "&"? What type will have "Object1(2)" in place2? Is it a constructor of the anonymous object? Will it have a "auto" storage type?

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  • any way to simplify this with a form of dynamic class instantiation?

    - by gnychis
    I have several child classes that extend a parent class, forced to have a uniform constructor. I have a queue which keeps a list of these classes, which must extend MergeHeuristic. The code that I currently have looks like the following: Class<? extends MergeHeuristic> heuristicRequest = _heuristicQueue.pop(); MergeHeuristic heuristic = null; if(heuristicRequest == AdjacentMACs.class) heuristic = new AdjacentMACs(_parent); if(heuristicRequest == SimilarInterfaceNames.class) heuristic = new SimilarInterfaceNames(_parent); if(heuristicRequest == SameMAC.class) heuristic = new SameMAC(_parent); Is there any way to simplify that to dynamically instantiate the class, something along the lines of: heuristic = new heuristicRequest.somethingSpecial(); That would flatten that block of if statements.

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  • C++ Static Array Initialization - Memory Issue

    - by donalmg
    Hi, I have a header file which contains a member variable declaration of a static char array: class ABC { public: static char newArray[4]; // other variables / functions private: void setArray(int i, char * ptr); } In the CPP file, I have the array initialized to NULL: char ABC::newArray[4] = {0}; In the ABC constructor, I need to overwrite this value with a value constructed at runtime, such as the encoding of an integer: ABC::ABC() { int i; //some int value defined at runtime memset(newArray, 0, 4); // not sure if this is necessary setArray(i,newArray); } ... void setArray(int i, char * value) { // encoding i to set value[0] ... value [3] } When I return from this function, and print the modified newArray value, it prints out many more characters than the 4 specified in the array declaration. Any ideas why this is the case. I just want to set the char array to 4 characters and nothing further. Thanks...

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  • What's the difference between => , ()=>, and Unit=>

    - by Malvolio
    I'm trying to represent a function that takes no arguments and returns no value (I'm simulating the setTimeout function in JavaScript, if you must know.) case class Scheduled(time : Int, callback : => Unit) doesn't compile, saying " `val' parameters may not be call-by-name" case class Scheduled(time : Int, callback : () => Unit) compiles, but has to be invoked strangely, instead of Scheduled(40, { println("x") } ) I have to do this Scheduled(40, { () => println("x") } ) What also works is class Scheduled(time : Int, callback : Unit => Unit) but is invoked in an even-less-sensible way Scheduled(40, { x : Unit => println("x") } ) (What would a variable of type Unit be?) What I want of course is a constructor that can be invoke the way I would invoke it if it were an ordinary function: Scheduled(40, println("x") ) Give baby his bottle!

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  • Calling a method on an object a bunch of times versus constructing an object a bunch of times

    - by Ami
    I have a List called myData and I want to apply a particular method (someFunction) to every element in the List. Is calling a method through an object's constructor slower than calling the same method many times for one particular object instantiation? In other words, is this: for(int i = 0; i < myData.Count; i++) myClass someObject = new myClass(myData[i]); slower than this: myClass someObject = new myClass(); for(int i = 0; i < myData.Count; i++) someObject.someFunction(myData[i]); ? If so, how much slower?

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  • Why does Generic class signature requires specifying new() if type T needs instantiation ?

    - by this. __curious_geek
    I'm writing a Generic class as following. public class Foo<T> : where T : Bar, new() { public void MethodInFoo() { T _t = new T(); } } As you can see the object(_t) of type T is instantiated at run-time. To support instantiation of generic type T, language forces me to put new() in the class signature. I'd agree to this if Bar is an abstract class but why does it need to be so if Bar standard non-abstract class with public parameter-less constructor. compiler prompts following message if new() is not found. Cannot create an instance of the variable type 'T' because it does not have the new() constraint

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  • How do i get (is it possible to) a reference to the class that creates an instance of another class.

    - by Cadde
    Odd situation... I need to create a new instance of a class that needs a member of the calling class. But i can't pass a reference to the calling class through the constructor. The solution i am looking for is something like this: Public Class ChildClass Public Sub New(args) _MyMember = GetMemberFromCallingClass() ... ... End Sub End Class I want this to work without having to manually pass any references or variables from the calling class to the new instance of ChildClass. Is this possible and if so, what should i look at to make this part of my code.

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  • Two phase Construction in C++

    - by tommieb75
    I have as part of assignment to look into a development kit that uses the "two-phase" construction for C++ classes: // Include Header class someFubar{ public: someFubar(); bool Construction(void); ~someFubar(); private: fooObject _fooObj; } In the source // someFubar.cpp someFubar::someFubar : _fooObj(null){ } bool someFubar::Construction(void){ bool rv = false; this->_fooObj = new fooObject(); if (this->_fooObj != null) rv = true; return rv; } someFubar::~someFubar(){ if (this->_fooObj != null) delete this->_fooObj; } Why would this "two-phase" be used and what benefits are there? Why not just instantiate the object initialization within the actual constructor?

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  • what is the purpose of numeric/boolean/string objects as opposed to primitive values?

    - by zespri
    In javascript you can call a function as a function or as a constructor. For example you can do : myObject = new Number(13); myPrimitiveValue = Number(13); or simply myPrimitiveValue = 13; I understand the difference between the results. Can you explain me under which reasonable circumstances creating a number, a boolean or a string as an object is desirable? For example, ability to set new properties (this is something you can do on objects but can't really do on primitive values) is almost always a bad idea for objects containing number/boolean/string. Why would I want a numeric/boolean/string object?

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  • Hiding instantiated templates in shared library created with g++

    - by jchl
    I have a file that contains the following: #include <map> class A {}; void doSomething() { std::map<int, A> m; } When compiled into a shared library with g++, the library contains dynamic symbols for all the methods of std::map<int, A>. Since A is private to this file, there is no possibility that std::map will be instantiated in any other shared library with the same parameters, so I'd like to make the template instantiation hidden (for some of the reasons described in this document). I thought I should be able to do this by adding an explicit instantiation of the template class and marking it as hidden, like so: #include <map> class A {}; template class __attribute__((visibility ("hidden"))) std::map<int, A>; void doSomething() { std::map<int, A> m; } However, this has no effect: the symbols are still all exported. I even tried compiling with -fvisibility=hidden, but this also has no effect on the visibility of the methods of std::map<int, A> (although it does hide doSomething). The document I linked to above describes the use of export maps to restrict visibility, but that seems very tedious. Is there a way to do what I want in g++ (other than using export maps)? If so, what is it? If not, is there a good reason why these symbols must always be exported, or is this just a omission in g++?

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