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• Serializing System.Drawing.Color in .NET

  - by alankdkd

  Hi all, I've used the default .NET serialization for a class with a System.Drawing.Color member. The code is now in use by people, and I need to add an extra member to the class, but still deserialize older versions. So I tried the standard way of doing this: The ISerializable interface, using SerializationInfo methods to get the int and string members. The problem: My class also has a System.Drawing.Color member, but SerializationInfo doesn't provide a "GetColor" method read this data type. I've tried getting it as an int and as a string, and casting it to System.Drawing.Color, but no luck. Does anyone know how to deserialize a System.Drawing.Color from SerializationInfo? Thanx! Alan

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• C99 strict aliasing rules in C++ (GCC)

  - by Checkers

  As far as I understand, GCC supports all of its C99 features in C++. But how is C99 strict aliasing handled in C++ code? I know that casting with C casts between unrelated types is not strict-aliasing-safe and may generate incorrect code, but what about C++? Since strict aliasing is not part of C++ standard (is that correct?), GCC must be specifying the semantics itself. I figure const_cast and static_cast cast between related types, hence they are safe, while reinterpret_cast can break strict aliasing rules. Is this a correct understanding?

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• Securing input of private / protected methods?

  - by ts

  Hello, normally, all sane developers are trying to secure input of all public methods (casting to proper types, validating, sanitizing etc.) My question is: are you in your code validating also parameters passed to protected / private methods? In my opinion it is not necessary, if you securize properly parameters of public methods and return values from outside (other classes, db, user input etc...). But I am constantly facing frameworks and apps (ie. prestashop to name one) where validation is often repeated in method call, in method body and once again for securize returned value - which, I think, is creating performace overhead and is also a sign of bad design.

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• Random select is not always returning a single row.

  - by Lieven

  The intention of following (simplified) code fragment is to return one random row. Unfortunatly, when we run this fragment in the query analyzer, it returns between zero and three results. As our input table consists of exactly 5 rows with unique ID's and as we perform a select on this table where ID equals a random number, we are stumped that there would ever be more than one row returned. Note: among other things, we already tried casting the checksum result to an integer with no avail. DECLARE @Table TABLE ( ID INTEGER IDENTITY (1, 1) , FK1 INTEGER ) INSERT INTO @Table SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 SELECT * FROM @Table WHERE ID = ABS(CHECKSUM(NEWID())) % 5 + 1

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• Inheritance - initialization problem

  - by dumbquestion

  I have a c++ class derived from a base class in a framework. The derived class doesn't have any data members because I need it to be freely convertible into a base class and back - the framework is responsible for loading and saving the objects and I can't change it. My derived class just has functions for accessing the data. But there are a couple of places where I need to store some temporary local variables to speed up access to data in the base class. mydata* MyClass::getData() { if ( !m_mydata ) { // set to NULL in the constructor m_mydata = some_long_and complex_operation_to_get_the_data_in_the_base() } return m_mydata; } The problem is if I just access the object by casting the base class pointer returned from the framework to MyClass* the ctor for MyClass is never called and m_mydata is junk. Is there a way of only initializing the m_mydata pointer once?

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• How to get a float value the pointer points to?

  - by aleluja

  Hello, In my app, i've created the TList type list where i store the pointers to 1 string and 2 float(real) values for every 3 items. aList.Add(@sName); //string aList.Add(@x1); //float aList.Add(@x2); //float Then, i want to get the values out from the list, but i could only do that for string sStr := string(lList.items[i]); But i couldn't get the float values as a := real(lList...) will result in an invalid typecast error. So what do i do to get the float values? Of course i have a question if that string casting will actually give me the string value. I'm not good at pointer stuff so i don't know how to do it.

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• What's an elegant solution to get the property values from two classes (that have the same property

  - by SlipToFall

  Essentially I have to deal with a poorly implemented web service. They have two classes that don't derive from a parent class, but have the same properties (Ughh...). So it looks like this in my web service proxy class file: public partial class Product1 { public int Quantity; public int Price; } public partial class Product2 { public int Quantity; public int Price; } So what's the best way to grab the values from known properties without duplicating the code and casting to their respective classes? I know I probably could use reflection, but that can get ugly. If there is an easier less crazier way to do it (maybe in the new c# features?) please let me know.

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• Lots of pointer casts in QGraphicsView framework and performance

  - by kleimola

  Since most of the convenience functions of QGraphicsScene and QGraphicsItem (such as items(), collidingItems(), childItems() etc.) return a QList you're forced to do lots of qgraphicsitem_cast or static_cast and QGraphicsItem::Type() checks to get hold of the actual items when you have lots of different type of items in the scene. I thought doing lots of subclass casts were not a desirable coding style, but I guess in this case there are no other viable way, or is there? QList<QGraphicsItem *> itemsHit = someItem->collidingItems(Qt::IntersectsItemShape); foreach (QGraphicsItem *item, itemsHit) { if (item->type() == QGraphicsEllipseItem::type()) { QGraphicsEllipseItem *ellipse = qgraphicsitem_cast<QGraphicsEllipseItem *>(item); // do something } else if (item->type() == MyItemSubclass::type()) { MyItemSubClass *myItem = qgraphicsitem_cast<MyItemSubClass *>(item); // do something } // etc } The above qgraphicsitem_cast could be replaced by static_cast since correct type is already verified. When doing lots of these all the time (very dynamic scene), will the numerous casting affect performance beyond the normal if-else evaluation?

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• Converting a PHP array to class variables.

  - by animuson

  Simple question, how do I convert an associative array to variables in a class? I know there is casting to do an (object) $myarray or whatever it is, but that will create a new stdClass and doesn't help me much. Are there any easy one or two line methods to make each $key => $value pair in my array into a $key = $value variable for my class? I don't find it very logical to use a foreach loop for this, I'd be better off just converting it to a stdClass and storing that in a variable, wouldn't I? class MyClass { var $myvar; // I want variables like this, so they can be references as $this->myvar function __construct($myarray) { // a function to put my array into variables } }

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• Retlang: What is the best way to unsubscribe from a channel?

  - by TrickyFishy

  I'm not sure what is the best way to unsubscribe from a channel when using Retlang. When you subscribe by calling ISubscriber<T>::Subscribe(...) you are returned an IUnsubscriber. This interface has no methods. Going up a level, IChannel<T> also does not have any methods. The only thing I can think of is casting an ISubscriber<T> to the concrete Channel<T> and calling its Unsubscribe() method or adding an Unsubscribe() method to ISubscriber<T>. I'm just curious if anyone knows what they had in mind before I modify the code.

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• Strange calculation problem in C multiply by 1.2 fails

  - by DoomStone

  I have this c code, where i need to calculate a dobule from a long. double result; long t2_value; t2_value = 72; result = t2_value * 1.2; Now this code crashes at "result = t2_value * 1.2;" only with the error "Vector 0000000006". Here is the strange thing, if i replace result = t2_value * 1.2; with result = 72 * 1.2; evything works just as it should, i have tryed type casting t2_value as an double result = ((double)t2_value * 1.2); or making it an int istead of a long, but nothing helps.

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• Filter condition not working properly on list (C#3.0)

  - by Newbie

  I have a datatable that has many NULL or " " strings. Next I am type casting the DataTable to a list . Now if I want to filter those conditions on this list and get the resultant value(without NULL or String.Empty or " " records) what should I do? My code DataTableExtensions.AsEnumerable(dt).ToList().ForEach(i => { if (i[0] != null) { if ((i[0].ToString() != string.Empty)|| (i[0].ToString() != " ")) { list = dt.AsEnumerable().ToList(); } } }); But I am getting all the records. It is not getting filtered. Using C#3.0 Please help Thanks

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• Return an opaque object to the caller without violating type-safety

  - by JS Bangs

  I have a method which should return a snapshot of the current state, and another method which restores that state. public class MachineModel { public Snapshot CurrentSnapshot { get; } public void RestoreSnapshot (Snapshot saved) { /* etc */ }; } The state Snapshot class should be completely opaque to the caller--no visible methods or properties--but its properties have to be visible within the MachineModel class. I could obviously do this by downcasting, i.e. have CurrentSnapshot return an object, and have RestoreSnapshot accept an object argument which it casts back to a Snapshot. But forced casting like that makes me feel dirty. What's the best alternate design that allows me to be both type-safe and opaque?

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• Cast vector<T> to vector<const T>

  - by user345386

  I have a member variable of type vector (where is T is a custom class, but it could be int as well.) I have a function from which I want to return a pointer to this vector, but I don't want the caller to be able to change the vector or it's items. So I want the return type to be const vector* None of the casting methods I tried worked. The compiler keeps complaining that T is not compatible with const T. Here's some code that demonstrates the gist of what I'm trying to do; vector<int> a; const vector<const int>* b = (const vector<const int>* ) (&a); This code doesn't compile for me. Thanks in advance!

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• aspectRatio = backingWidth / backingHeight ???

  - by carrots

  What am I doing wrong here, I can't get the result of this division: aspectRatio = backingWidth / backingHeight; I've thought I might try casting to (GLfloat) but that didn't do anything. As I step through the code I see that aspectRatio is 0 after the operation, while backingWidth is clearly 768 and backingHeight is 1029. Here are the types: GLfloat aspectRatio; and // The pixel dimensions of the CAEAGLLayer GLint backingWidth; GLint backingHeight; It must be something basic I'm doing wrong here..

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• iOS sdk question: how do I cast a UIView to a UIImage View (alternativly how do I get a UIImageView from a GestureRecognzer?)

  - by user439299

  Desired end result: user taps a UIImageView and the image changes to another image (a subsequent tap returns the image to the original state) Problem: I add a (unique) selector to a bunch of UIImageViews (in an array) and point the action at the same function - let's call this function imageTapped: for now. Here is my code so far: -(void)imageTapped:(UITapGestureRecognizer *)tapGesture { UIImageView *view = tapGesture.view; // rest of code... } This code actually works fine but gets a warning when I run it: "Incompatible objective c types initilizing 'struct UIView *', expected 'struct UIImageView *' Any way to get rid of this? Not sure how casting works in objective c... primitive types seem to work fine such as (int)someFloat works fine but (UIImageView)someUiView doesn't work. Like I said, code works alright when I run it but would like to get ride of the compiler warning. Any help would be awesome.... I am very new to objective c (or any non java language for that matter) so be gentle. Thanks in advance.

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• Calculate difference in days ActiveSupport:TimeWithZone in the most "rubyish" style?

  - by Nick

  I have a feeling someone is going to point me to another question that answers this but I've been searching with no luck over this simple issue. I have a Activerecord with a datetime property. It returns as an ActiveSupport:TimeWithZone. I know I can't compare that to DateTime.now because that doesn't include a zone so I need to use Time.zone. Makes sense. What I'm wondering is stylewise is there a "cleaner" way to do this than subtracting and dividing the result by 86400? Here's what I do: ((Time.zone.now - myActiveRecord.visit_date)/86400).to_i Works but seems un-rubyish and I feel like I'm missing something. Should I be casting, comparing or converting some other route or is this really the typical way to do this in rails? Appreciate any tips or a link to a question that already covers this. Thank you

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• Handling null values with PowerShell dates

  - by Tim Ferrill

  I'm working on a module to pull data from Oracle into a PowerShell data table, so I can automate some analysis and perform various actions based on the results. Everything seems to be working, and I'm casting columns into specific types based on the column type in Oracle. The problem I'm having has to do with null dates. I can't seem to find a good way to capture that a date column in Oracle has a null value. Is there any way to cast a [datetime] as null or empty?

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• How to deal with the Hibernate hql multi-join query result in an Object-Oriented Way?

  - by EugeneP

  How to deal with the Hibernate hql multi-join query result in an Object-Oriented Way? As I see it returns a list of Objects. yes, it is tricky and only you who write the query know what should the query return (what objects). But are there ways to simplify things, so that it returned specific objects with no need in casting Object to a specific class according to its position in the query ? Maybe Spring can simplify things here? It has the similar functionality for JDBC, but I don't see if it can help in a similar way with Hibernate.

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• C# SQL SELECT Statement

  - by Feren6

  I have the following code: SqlCommand cmd2 = new SqlCommand("SELECT ClaimId FROM tblPayment WHERE PaymentId = " + PaymentID.ToString(), mvarDBConn); SqlDataReader reader = cmd2.ExecuteReader(); reader.Read(); Int32 ClaimId = reader.GetInt32(0); reader.Close(); If I run the SELECT statement in SQL it returns the number fine, but when I use ExecuteReader all it returns is 0. I've tried multiple methods including ExecuteScalar, ExecuteNonQuery, reader.GetString then casting that to an int, etc. What am I missing? Thanks.

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• PHP 1-liner each() with mysql_fetch_assoc()

  - by MVC You Know Me

  Hey All. Trying to create a 1-liner to loop through a mysql result set. Example: $sql = "SELECT uid, role FROM usr WHERE uid = '$this-uid'"; $r = db::q($sql); if($r-rows()) { $q = mysql_fetch_assoc($r-result); while(list($k, $v) = each($q)) { // would like to omit line above and consolidate here $_SESSION['usr'][$k] = $this->$k = $v; } } problem is that consolidating while loop like so: while(list($k, $v) = each(mysql_fetch_assoc($r-result)) returns an error a la each() not getting object or array, even though of course it is. I think the problem is a casting issue, but it does not seem you can do: each( (array) mysql_fetch_assoc($r-result)) Any ideas? I like to code as tersely as possible, and having "$q = mysql_fetch_assoc($r-result)" everywhere will annoy me, does already. Keep posted... Thanks!

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• List.ForEach method and collection interfaces

  - by tyndall

  In .NET 3.5 List< gains a ForEach method. I notice this does not exist on IList< or IEnumerable< what was the thinking here? Is there another way to do this? Nice and simple short way to do this? I ask because I was at a talk where the speaker said always use the more general interfaces. But why would I use IList< as a return type if I want to be able to turn around and use ForEach? Then I would just end up casting it back to a List<.

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• Visual C++ CreateThread Parameter Problem

  - by Vanwaril

  I have a class that contains a function that calls create thread, and needs to pass itself (this) as a parameter: DWORD threadId; HANDLE h = CreateThread( NULL, 0, runThread, this, 0, &threadId); My runThread definition is as follows: DWORD WINAPI runThread(LPVOID args) { Obj *t = (Obj*)args; t->funct(); return 0; } Unfortunately, the object t that I get in runThread() gets garbage. My Obj class has a function pointer attribute. Could that be the problem? class Obj{ void(*funct)(); and in the constructor: Obj(void(*f)()) { funct = f; } where is my mistake? The function pointer, the createThread itself, or type-casting? I tried whatever I could think of.

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• Abstract class and operator!= in c++

  - by Alessandro Teruzzi

  Hi All, I have problem implementing the operator!= in a set class deriving from an abstact one. The code looks like this: class Abstract { public: //to make the syntax easier let's use a raw pointer virtual bool operator!=(const Abstract* other) = 0; }; class Implementation { SomeObject impl_; //that already implement the operator!= public: bool operator!=(const Abstract* other) { return dynamic_cast<Implementation*>(other)->impl_ != this->impl_; } }; This code works but it has the drawback to use dynamic_cast and I need to handle error in casting operation. This is a generic problem that occur when a function of a concrete class it is trying to using some internal information (not available at the abstract class level) to perform a task. Is there any better way to solve this kind of problem? Cheers

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• C# Why does calling an interface member from a class generate an error?

  - by Jack

  So I have an interface: interface IFoo { int Bar(); int this[int i] {get; set;} } And a class that derives from it class Foo : IFoo { public int IFoo.Bar() { //Implementation { public int IFoo.this[int i] { //Implementation } } Now, I try to do this: var fooey = new Foo(); int i = Fooey.Bar(); or this: int i = Fooey[4]; I would expect these to work properly. However, the compiler generates an error as if such members don't exist. Why is that? I am aware I can cast Foo as IFoo, but I am also aware that casting is costly to performance, which is often the reason to use interfaces in the first place. EDIT 1: These are the errors generated 'Foo' does not contain a definition for 'Bar' and no extension method 'Bar' accepting a first argument of type 'Foo' could be found (are you missing a using directive or an assembly reference?) "Cannot apply indexing to an expression of type 'Foo'"

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