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• NullReferenceException at Microsoft.Silverlight.Build.Tasks.CompileXaml.LoadAssemblies(ITaskItem[] R

  - by Eugene Larchick

  Hi, I updated my Visual Studio 2010 to the version 10.0.30319.1 RTM Rel and start getting the following exception during the build: System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.Silverlight.Build.Tasks.CompileXaml.LoadAssemblies(ITaskItem[] ReferenceAssemblies) at Microsoft.Silverlight.Build.Tasks.CompileXaml.get_GetXamlSchemaContext() at Microsoft.Silverlight.Build.Tasks.CompileXaml.GenerateCode(ITaskItem item, Boolean isApplication) at Microsoft.Silverlight.Build.Tasks.CompileXaml.Execute() at Bohr.Silverlight.BuildTasks.BohrCompileXaml.Execute() The code of BohrCompileXaml.Execute is the following: public override bool Execute() { List<TaskItem> pages = new List<TaskItem>(); foreach (ITaskItem item in SilverlightPages) { string newFileName = getGeneratedName(item.ItemSpec); String content = File.ReadAllText(item.ItemSpec); String parentClassName = getParentClassName(content); if (null != parentClassName) { content = content.Replace("<UserControl", "<" + parentClassName); content = content.Replace("</UserControl>", "</" + parentClassName + ">"); content = content.Replace("bohr:ParentClass=\"" + parentClassName + "\"", ""); } File.WriteAllText(newFileName, content); pages.Add(new TaskItem(newFileName)); } if (null != SilverlightApplications) { foreach (ITaskItem item in SilverlightApplications) { Log.LogMessage(MessageImportance.High, "Application: " + item.ToString()); } } foreach (ITaskItem item in pages) { Log.LogMessage(MessageImportance.High, "newPage: " + item.ToString()); } CompileXaml xamlCompiler = new CompileXaml(); xamlCompiler.AssemblyName = AssemblyName; xamlCompiler.Language = Language; xamlCompiler.LanguageSourceExtension = LanguageSourceExtension; xamlCompiler.OutputPath = OutputPath; xamlCompiler.ProjectPath = ProjectPath; xamlCompiler.RootNamespace = RootNamespace; xamlCompiler.SilverlightApplications = SilverlightApplications; xamlCompiler.SilverlightPages = pages.ToArray(); xamlCompiler.TargetFrameworkDirectory = TargetFrameworkDirectory; xamlCompiler.TargetFrameworkSDKDirectory = TargetFrameworkSDKDirectory; xamlCompiler.BuildEngine = BuildEngine; bool result = xamlCompiler.Execute(); // HERE we got the error! And the definition of the task: <BohrCompileXaml LanguageSourceExtension="$(DefaultLanguageSourceExtension)" Language="$(Language)" SilverlightPages="@(Page)" SilverlightApplications="@(ApplicationDefinition)" ProjectPath="$(MSBuildProjectFullPath)" RootNamespace="$(RootNamespace)" AssemblyName="$(AssemblyName)" OutputPath="$(IntermediateOutputPath)" TargetFrameworkDirectory="$(TargetFrameworkDirectory)" TargetFrameworkSDKDirectory="$(TargetFrameworkSDKDirectory)" > <Output ItemName="Compile" TaskParameter="GeneratedCodeFiles" /> <!-- Add to the list list of files written. It is used in Microsoft.Common.Targets to clean up for a next clean build --> <Output ItemName="FileWrites" TaskParameter="WrittenFiles" /> <Output ItemName="_GeneratedCodeFiles" TaskParameter="GeneratedCodeFiles" /> </BohrCompileXaml> What can be the reason? And how can I get more info what's happening inside CompileXaml class?

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• Can I use the [] operator in C++ to create virtual arrays

  - by Shane MacLaughlin

  I have a large code base, originally C ported to C++ many years ago, that is operating on a number of large arrays of spatial data. These arrays contain structs representing point and triangle entities that represent surface models. I need to refactor the code such that the specific way these entities are stored internally varies for specific scenarios. For example if the points lie on a regular flat grid, I don't need to store the X and Y coordinates, as they can be calculated on the fly, as can the triangles. Similarly, I want to take advantage of out of core tools such as STXXL for storage. The simplest way of doing this is replacing array access with put and get type functions, e.g. point[i].x = XV; becomes Point p = GetPoint(i); p.x = XV; PutPoint(i,p); As you can imagine, this is a very tedious refactor on a large code base, prone to all sorts of errors en route. What I'd like to do is write a class that mimics the array by overloading the [] operator. As the arrays already live on the heap, and move around with reallocs, the code already assumes that references into the array such as point *p = point + i; may not be used. Is this class feasible to write? For example writing the methods below in terms of the [] operator; void MyClass::PutPoint(int Index, Point p) { if (m_StorageStrategy == RegularGrid) { int xoffs,yoffs; ComputeGridFromIndex(Index,xoffs,yoffs); StoreGridPoint(xoffs,yoffs,p.z); } else m_PointArray[Index] = p; } } Point MyClass::GetPoint(int Index) { if (m_StorageStrategy == RegularGrid) { int xoffs,yoffs; ComputeGridFromIndex(Index,xoffs,yoffs); return GetGridPoint(xoffs,yoffs); // GetGridPoint returns Point } else return m_PointArray[Index]; } } My concern is that all the array classes I've seen tend to pass by reference, whereas I think I'll have to pass structs by value. I think it should work put other than performance, can anyone see any major pitfalls with this approach. n.b. the reason I have to pass by value is to get point[a].z = point[b].z + point[c].z to work correctly where the underlying storage type varies.

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• Translating a C# WCF app into Visual Basic

  - by MikeG

  I'm trying to write a simple/small Windows Communication Foundation service application in Visual Basic (but I am very novice in VB) and all the good examples I've found on the net are written in C#. So far I've gotten my WCF service application working but now I'm trying to add callback functionality and the program has gotten more complicated. In the C# example code I understand how everything works but I am having trouble translating into VB the portion of code that uses a delegate. Can someone please show the VB equivalent? Here is the C# code sample I'm using for reference: namespace WCFCallbacks { using System; using System.ServiceModel; [ServiceContract(CallbackContract = typeof(IMessageCallback))] public interface IMessage { [OperationContract] void AddMessage(string message); [OperationContract] bool Subscribe(); [OperationContract] bool Unsubscribe(); } interface IMessageCallback { [OperationContract(IsOneWay = true)] void OnMessageAdded(string message, DateTime timestamp); } } namespace WCFCallbacks { using System; using System.Collections.Generic; using System.ServiceModel; public class MessageService : IMessage { private static readonly List<IMessageCallback> subscribers = new List<IMessageCallback>(); //The code in this AddMessage method is what I'd like to see re-written in VB... public void AddMessage(string message) { subscribers.ForEach(delegate(IMessageCallback callback) { if (((ICommunicationObject)callback).State == CommunicationState.Opened) { callback.OnMessageAdded(message, DateTime.Now); } else { subscribers.Remove(callback); } }); } public bool Subscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); if (!subscribers.Contains(callback)) subscribers.Add(callback); return true; } catch { return false; } } public bool Unsubscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); if (!subscribers.Contains(callback)) subscribers.Remove(callback); return true; } catch { return false; } } } } I was thinking I could do something like this but I don't know how to pass the message string from AddMessage to DoSomething... Dim subscribers As New List(Of IMessageCallback) Public Sub AddMessage(ByVal message As String) Implements IMessage.AddMessage Dim action As Action(Of IMessageCallback) action = AddressOf DoSomething subscribers.ForEach(action) 'Or this instead of the above three lines: 'subscribers.ForEach(AddressOf DoSomething) End Sub Public Sub DoSomething(ByVal callback As IMessageCallback) 'I am also confused by: '((ICommunicationObject)callback).State 'Is that casting the callback object as type ICommunicationObject? 'How is that done in VB? End Sub

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• Mobile Safari text selection after input field focus

  - by Andy

  I have some legacy html that needs to work on old and new browsers (down to IE7) as well as the iPad. The iPad is the biggest issues because of how text selection is handled. On a page there is a textarea as well as some text instructions. The instructions are in a <div> and the user needs to be able to select the instructions. The problem is that once focus is placed in the textarea, the user cannot subsequently select the text instructions in the <div>. This is because the text cannot receive focus. According to the Safari Web Content Guide: Handling Events (especially, "Making Elements Clickable"), you can add a onclick event handler to the div you want to receive focus. This solution works (although it is not ideal) in iOS 6x but it does not work in iOS 5x. Does anyone have a suggestion that minimizes changes to our existing code and produces consistant user interaction. Here is sample code that shows the problem. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <script src="http://code.jquery.com/jquery-1.8.2.js"></script> <!-- Resources: Safari Web Content Guide: Handling Events (especially, "Making Elements Clickable") http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/HandlingEvents/HandlingEvents.html#//apple_ref/doc/uid/TP40006511-SW1 --> </head> <body> <div style="width:550"> <div onclick='function() { void(0); }'> <p>On the iPad, I want to be able to select this text after the textarea has had focus.</p> </div> <textarea rows="20" cols="80">After focus is in the textarea, can you select the text above?</textarea> </div> </body> </html>

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• Problems with starting windows service on windows xp SP3

  - by Michiel Peeters

  I'm currently facing a problem which I can not resolve and I really don't know what to do anymore. When I'm trying to start the service I receive the message: "The service is started but again also stopped, this because that some of the services will stop if they have nothing to do, for example the performance logs and the alerts service". I've looked into the Windows Logs but nothing is written there which could describe why my service is all the time stopping. I've also tried to fire the windows service via the command prompt which gives me the message: "The service is not started, but the service didn't return any faults.". I've tried to remove all keys which references to my service, which didn't resolve the issue. I've searched on google (maybe not good enough) to find an answer but I didn't found any. I did found some websites which describes what I could do, but all of these suggestions didn't work. This is kinda ** because I do not know where to look. I do not have any error message, i do not have any id which i can use to search on. I really don't know where to start and I hope you guys can help me on this one. Detailed explanation about the windows service OS: Windows XP SP3 .Net Framework: .Net 4.0 Client Profile Language: C# Development environment: Visual Studio 2010 Professional (but Visual Studio 2012 RC is installed) Communications: WCF (Named Pipes), WCF (BasicHTTPBinding) Named Pipes: I have chosen for this solution because I wanted to communicate from a windows service to a windows form application. It worked now for quite some time but suddenly my windows service shuts it self down and I couldn't restart it anymore. There are two named pipes services implemented: An event service which will send any notification to the windows form application and an management service which gives my windows form application the possibility to maintain my windows service. BasicHTTPBinding: The basic http binding makes the connection to a central server. This connection is then used for streaming information from the client to the server. I do not know which additional information you will need, but if you guys need something then I'll try to give it as detailed as possible. Thank you in advance.

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• Sorting a list of numbers with modified cost

  - by David

  First, this was one of the four problems we had to solve in a project last year and I couldn’t find a suitable algorithm so we handle in a brute force solution. Problem: The numbers are in a list that is not sorted and supports only one type of operation. The operation is defined as follows: Given a position i and a position j the operation moves the number at position i to position j without altering the relative order of the other numbers. If i j, the positions of the numbers between positions j and i - 1 increment by 1, otherwise if i < j the positions of the numbers between positions i+1 and j decreases by 1. This operation requires i steps to find a number to move and j steps to locate the position to which you want to move it. Then the number of steps required to move a number of position i to position j is i+j. We need to design an algorithm that given a list of numbers, determine the optimal (in terms of cost) sequence of moves to rearrange the sequence. Attempts: Part of our investigation was around NP-Completeness, we make it a decision problem and try to find a suitable transformation to any of the problems listed in Garey and Johnson’s book: Computers and Intractability with no results. There is also no direct reference (from our point of view) to this kind of variation in Donald E. Knuth’s book: The art of Computer Programing Vol. 3 Sorting and Searching. We also analyzed algorithms to sort linked lists but none of them gives a good idea to find de optimal sequence of movements. Note that the idea is not to find an algorithm that orders the sequence, but one to tell me the optimal sequence of movements in terms of cost that organizes the sequence, you can make a copy and sort it to analyze the final position of the elements if you want, in fact we may assume that the list contains the numbers from 1 to n, so we know where we want to put each number, we are just concerned with minimizing the total cost of the steps. We tested several greedy approaches but all of them failed, divide and conquer sorting algorithms can’t be used because they swap with no cost portions of the list and our dynamic programing approaches had to consider many cases. The brute force recursive algorithm takes all the possible combinations of movements from i to j and then again all the possible moments of the rest of the element’s, at the end it returns the sequence with less total cost that sorted the list, as you can imagine the cost of this algorithm is brutal and makes it impracticable for more than 8 elements. Our observations: n movements is not necessarily cheaper than n+1 movements (unlike swaps in arrays that are O(1)). There are basically two ways of moving one element from position i to j: one is to move it directly and the other is to move other elements around i in a way that it reaches the position j. At most you make n-1 movements (the untouched element reaches its position alone). If it is the optimal sequence of movements then you didn’t move the same element twice.

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• Rspec and Rails 3 - Problem Validating Nested Attribute Collection Size

  - by MunkiPhD

  When I create my Rspec tests, I keep getting a validation of false as opposed to true for the following tests. I've tried everything and the following is the measly code that I have now - so if it's waaaaay wrong, that's why. class Master < ActiveRecord::Base attr_accessible :name, :specific_size # Associations ---------------------- has_many :line_items accepts_nested_attributes_for :line_items, :allow_destroy => true, :reject_if => lambda { |a| a[:item_id].blank? } # Validations ----------------------- validates :name, :presence => true, :length => {:minimum => 3, :maximum => 30} validates :specific_size, :presence => true, :length => {:minimum => 4, :maximum => 30} validate :verify_items_count def verify_items_count if self.line_items.size < 2 errors.add(:base, "Not enough items to create a master") end end end And here it the items model: class LineItem < ActiveRecord::Base attr_accessible :specific_size, :other_item_type_id # Validations -------------------- validates :other_item_type_id, :presence => true validates :master_id, :presence => true validates :specific_size, :presence => true # Associations --------------------- belongs_to :other_item_type belongs_to :master end The RSpec Tests: before(:each) do @master_lines = [] @master_lines << LineItem.new(:other_item_type_id => 1, :master_id => 2, :specific_size => 1) @master_lines << LineItem.new(:other_item_type_id => 2, :master_id => 2, :specific_size => 1) @attr = {:name => "Some Master", :specific_size => "1 giga"} end it "should create a new instance given a valid name and specific size" do @master = Master.create(@attr) line_item_one = @master.line_items.build(:other_item_type_id => 1, :specific_size => 1) line_item_two = @master.line_items.build(:other_item_type_id => 2, :specific_size => 2) @master.line_items.size === 2 @master.should be_valid end it "should have at least two items to be valid" do master = Master.new(:name => "test name", :specific_size => "1 mega") master_item_one = LineItem.new(:other_item_type_id => 1, :specific_size => 2) master_item_two = LineItem.new(:other_item_type_id => 2, :specific_size => 1) master.line_items << master_item_one master.should_not be_valid master.line_items << master_item_two master.line_items.size.should === 2 master.should be_valid end I'm very new to Rspec and Rails - and I've been failing at this for the past couple of hours. Thanks for any help in advance.

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• How can I link two Java serialised objects back together?

  - by Kidburla

  Sometimes (quite a lot, actually) we get a situation in Java where two objects are pointing to the same thing. Now if we serialise these separately it is quite appropriate that the serialised forms have separate copies of the object as it should be possible to open one without the other. However if we now deserialise them both, we find that they are still separated. Is there any way to link them back together? Example follows. public class Example { private static class ContainerClass implements java.io.Serializable { private ReferencedClass obj; public ReferencedClass get() { return obj; } public void set(ReferencedClass obj) { this.obj = obj; } } private static class ReferencedClass implements java.io.Serializable { private int i = 0; public int get() { return i; } public void set(int i) { this.i = i; } } public static void main(String[] args) throws Exception { //Initialise the classes ContainerClass test1 = new ContainerClass(); ContainerClass test2 = new ContainerClass(); ReferencedClass ref = new ReferencedClass(); //Make both container class point to the same reference test1.set(ref); test2.set(ref); //This does what we expect: setting the integer in one (way of accessing the) referenced class sets it in the other one test1.get().set(1234); System.out.println(Integer.toString(test2.get().get())); //Now serialise the container classes java.io.ObjectOutputStream os = new java.io.ObjectOutputStream(new java.io.FileOutputStream("C:\\Users\\Public\\test1.ser")); os.writeObject(test1); os.close(); os = new java.io.ObjectOutputStream(new java.io.FileOutputStream("C:\\Users\\Public\\test2.ser")); os.writeObject(test2); os.close(); //And deserialise them java.io.ObjectInputStream is = new java.io.ObjectInputStream(new java.io.FileInputStream("C:\\Users\\Public\\test1.ser")); ContainerClass test3 = (ContainerClass)is.readObject(); is.close(); is = new java.io.ObjectInputStream(new java.io.FileInputStream("C:\\Users\\Public\\test2.ser")); ContainerClass test4 = (ContainerClass)is.readObject(); is.close(); //We expect the same thing as before, and would expect a result of 4321, but this doesn't happen as the referenced objects are now separate instances test3.get().set(4321); System.out.println(Integer.toString(test4.get().get())); } }

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• Best way to have common class shared by both C++ and Ruby?

  - by shuttle87

  I am currently working on a project where a team of us are designing a game, all of us are proficient in ruby and some (but not all) of us are proficient in c++. Initially we made the backend in ruby but we ported it to c++ for more speed. The c++ port of the backend has exactly the same features and algorithms as the original ruby code. However we still have a bunch of code in ruby that does useful things but we want it to now get the data from the c++ classes. Our first thought was that we could save some of the data structures in something like XML or redis and call that, but some of the developers don't like that idea. We don't need anything particularly complex data structures to be passed between the different parts of the code, just tuples, strings and ints. Is there any way of integrating the ruby code so that it can call the c++ stuff natively? Will we need to embed code? Will we have to make a ruby extension? If so are there any good resources/tutorials you could suggest? For example say we have this code in the c++ backend: class The_game{ private: bool printinfo; //print the player diagnostic info at the beginning if true int numplayers; std::vector<Player*> players; string current_action; int action_is_on; // the index of the player in the players array that the action is now on //more code here public: Table(std::vector<Player *> in_players, std::vector<Statistics *> player_stats ,const int in_numplayers); ~Table(); void play_game(); History actions_history; }; class History{ private: int action_sequence_number; std::vector<Action*> hand_actions; public: void print_history(); void add_action(Action* the_action_to_be_added); int get_action_sequence_number(){ return action_sequence_number;} bool history_actions_are_equal(); int last_action_size(int street,int number_of_actions_ago); History(); ~History(); }; Is there any way to natively call something in the actions_history via The_game object in ruby? (The objects in the original ruby code all had the same names and functionality) By this I mean: class MyRubyClass def method1(arg1) puts arg1 self.f() # ... but still available puts cpp_method.the_current_game.actions_history.get_action_sequence_number() end # Constructor: def initialize(arg) puts "In constructor with arg #{arg}" #get the c++ object here and call it cpp_method end end Is this possible? Any advice or suggestions are appreciated.

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• Directly Jump to another C++ function

  - by maligree

  I'm porting a small academic OS from TriCore to ARM Cortex (Thumb-2 instruction set). For the scheduler to work, I sometimes need to JUMP directly to another function without modifying the stack nor the link register. On TriCore (or, rather, on tricore-g++), this wrapper template (for any three-argument-function) works: template< class A1, class A2, class A3 > inline void __attribute__((always_inline)) JUMP3( void (*func)( A1, A2, A3), A1 a1, A2 a2, A3 a3 ) { typedef void (* __attribute__((interrupt_handler)) Jump3)( A1, A2, A3); ( (Jump3)func )( a1, a2, a3 ); } //example for using the template: JUMP3( superDispatch, this, me, next ); This would generate the assembler instruction J (a.k.a. JUMP) instead of CALL, leaving the stack and CSAs unchanged when jumping to the (otherwise normal) C++ function superDispatch(SchedulerImplementation* obj, Task::Id from, Task::Id to). Now I need an equivalent behaviour on ARM Cortex (or, rather, for arm-none-linux-gnueabi-g++), i.e. generate a B (a.k.a. BRANCH) instruction instead of BLX (a.k.a. BRANCH with link and exchange). But there is no interrupt_handler attribute for arm-g++ and I could not find any equivalent attribute. So I tried to resort to asm volatile and writing the asm code directly: template< class A1, class A2, class A3 > inline void __attribute__((always_inline)) JUMP3( void (*func)( A1, A2, A3), A1 a1, A2 a2, A3 a3 ) { asm volatile ( "mov.w r0, %1;" "mov.w r1, %2;" "mov.w r2, %3;" "b %0;" : : "r"(func), "r"(a1), "r"(a2), "r"(a3) : "r0", "r1", "r2" ); } So far, so good, in my theory, at least. Thumb-2 requires function arguments to be passed in the registers, i.e. r0..r2 in this case, so it should work. But then the linker dies with undefined reference to `r6' on the closing bracket of the asm statement ... and I don't know what to make of it. OK, I'm not the expert in C++, and the asm syntax is not very straightforward... so has anybody got a hint for me? A hint to the correct __attribute__ for arm-g++ would be one way, a hint to fix the asm code would be another. Another way maybe would be to tell the compiler that a1..a3 should already be in the registers r0..r2 when the asm statement is entered (I looked into that a bit, but did not find any hint).

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• JQM dialog is opening in new page instead of dialog

  - by K D

  Thank you for taking the time to read my question. I'm trying to get a dialog box to open using Jquery mobile. I followed the documentation and used the data-rel="dialog" notation along with the data-transition="pop". Instead of a dialog appearing on the same page, I get a brand new page with the dialog appearing. Can someone kindly assist me on how to fix this functionality. Here is my code for the initial main page: <article> <ul data-role="listview" data-split-icon="star" data-split-theme="d" data-inset="true"> <li><a href="#black_seed_desc" data-rel="dialog" ><img src="black_seed.jpg"/> <h3>Black Seed Oil</h3> </a> <a href="#black_seed_purchase" data-rel="dialog" data-transition="pop">Purchase Black Seed Oil</a> </li> </ul> </article> Here is my code for the dialog page: <div data-role="dialog" id="black_seed_purchase" data-theme="c"> <section data-role="content"> <h1>Purchase Black Seed Oil?</h1> <p>By purchasing Black Seed Oil you will receive an email receipt copy sent to you for your reference.</p> <a href="#purchase_blackseed" data-inline="true" data-corners="true" data-rel="back" data-role="button" data-shadow="true" data-iconshadow="true" data-wrapperrels="span"> <span> <span>Buy: $49.99</span> <span>&nbsp;</span> </span> </a> <a href="#" data-role="button" data-rel="back" data-inline="true" data-corners="true" data-wrapperrels="span" data-shadow="true" data-iconshawdow="true"> <span> Cancel </span> </a> </section> </div> Here is a working example. http://jsfiddle.net/Gajotres/w3ptm/?

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• Is 4-5 years the “Midlife Crisis” for a programming career?

  - by Jeffrey

  I’ve been programming C# professionally for a bit over 4 years now. For the past 4 years I’ve worked for a few small/medium companies ranging from “web/ads agencies”, small industry specific software shops to a small startup. I've been mainly doing "business apps" that involves using high-level programming languages (garbage collected) and my overall experience was that all of the works I’ve done could have been more professional. A lot of the things were done incorrectly (in a rush) mainly due to cost factor that people always wanted something “now” and with the smallest amount of spendable money. I kept on thinking maybe if I could work for a bigger companies or a company that’s better suited for programmers, or somewhere that's got the money and time to really build something longer term and more maintainable I may have enjoyed more in my career. I’ve never had a “mentor” that guided me through my 4 years career. I am pretty much blog / google / self taught programmer other than my bachelor IT degree. I’ve also observed another issue that most so called “senior” programmer in “my working environment” are really not that senior skill wise. They are “senior” only because they’ve been a long time programmer, but the code they write or the decisions they make are absolutely rubbish! They don't want to learn, they don't want to be better they just want to get paid and do what they've told to do which make sense and most of us are like that. Maybe that’s why they are where they are now. But I don’t want to become like them I want to be better. I’ve run into a mental state that I no longer intend to be a programmer for my future career. I started to think maybe there are better things out there to work on. The more blogs I read, the more “best practices” I’ve tried the more I feel I am drifting away from “my reality”. But I am not a great programmer otherwise I don't think I am where I am now. I think 4-5 years is a stage that can be a step forward career wise or a step out of where you are. I just wanted to hear what other have to say about what I’ve mentioned above and whether you’ve experienced similar situation in your past programming career and how you dealt with it. Thanks.

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• sqlite eatingup memory on iPhone when doing insert

  - by kviksilver

  I am having problem with inserting data to sqlite database. char *update="INSERT OR REPLACE INTO ct_subject (id,id_parent, title, description, link, address, phone, pos_lat, pos_long, no_votes, avg_vote, photo, id_comerc, id_city, placement, type, timestamp, mail) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?);"; sqlite3_stmt *stmt; if(sqlite3_prepare_v2(database, update, -1, &stmt, nil) == SQLITE_OK){ sqlite3_bind_int(stmt, 1, [[[newCategories objectAtIndex:i] valueForKey:@"id"] intValue]); sqlite3_bind_int(stmt, 2, [[[newCategories objectAtIndex:i] valueForKey:@"id_parent"] intValue]); sqlite3_bind_text(stmt, 3, [[[newCategories objectAtIndex:i] valueForKey:@"title"] UTF8String], -1, NULL); sqlite3_bind_text(stmt, 4, [[[newCategories objectAtIndex:i] valueForKey:@"description"] UTF8String], -1, NULL); sqlite3_bind_text(stmt, 5, [[[newCategories objectAtIndex:i] valueForKey:@"link"] UTF8String], -1, NULL); sqlite3_bind_text(stmt, 6, [[[newCategories objectAtIndex:i] valueForKey:@"address"] UTF8String], -1, NULL); sqlite3_bind_text(stmt, 7, [[[newCategories objectAtIndex:i] valueForKey:@"phone"] UTF8String], -1, NULL); sqlite3_bind_text(stmt, 8, [[[newCategories objectAtIndex:i] valueForKey:@"pos_lat"] UTF8String], -1, NULL); sqlite3_bind_text(stmt, 9, [[[newCategories objectAtIndex:i] valueForKey:@"pos_long"] UTF8String], -1, NULL); sqlite3_bind_int(stmt, 10, [[[newCategories objectAtIndex:i] valueForKey:@"no_votes"] intValue]); sqlite3_bind_text(stmt, 11, [[[newCategories objectAtIndex:i] valueForKey:@"avg_vote"] UTF8String], -1, NULL); if ([[[newCategories objectAtIndex:i] valueForKey:@"photo"] length]!=0) { NSMutableString *webUrl = (NSMutableString *)[[NSMutableString alloc] initWithString:@"http://www.crotune.com/public/images/subjects/"]; [webUrl appendString:[[newCategories objectAtIndex:i] valueForKey:@"photo"]]; UIImage *myImage = [self getWebImage:webUrl]; if(myImage != nil){ sqlite3_bind_blob(stmt, 12, [UIImagePNGRepresentation(myImage) bytes], [UIImagePNGRepresentation(myImage) length], NULL); } else { sqlite3_bind_blob(stmt, 12, nil, -1, NULL); } [webUrl release]; [myImage release]; } else { sqlite3_bind_blob(stmt, 12, nil, -1, NULL); //NSLog(@" ne dodajem sliku2"); } sqlite3_bind_int(stmt, 13, [[[newCategories objectAtIndex:i] valueForKey:@"id_comerc"] intValue]); sqlite3_bind_int(stmt, 14, [[[newCategories objectAtIndex:i] valueForKey:@"id_city"] intValue]); sqlite3_bind_int(stmt, 15, [[[newCategories objectAtIndex:i] valueForKey:@"placement"] intValue]); sqlite3_bind_int(stmt, 16, [[[newCategories objectAtIndex:i] valueForKey:@"type"] intValue]); sqlite3_bind_int(stmt, 17, [[[newCategories objectAtIndex:i] valueForKey:@"timestamp"] intValue]); sqlite3_bind_text(stmt, 18, [[[newCategories objectAtIndex:i] valueForKey:@"mail"] UTF8String], -1, NULL); } if (sqlite3_step(stmt) != SQLITE_DONE) { NSLog(@"%s", sqlite3_errmsg(database)); NSAssert1(0,@"nemogu updateat table %s", errorMsg); } else { NSLog(@"Ubacio %d",i); }sqlite3_finalize(stmt); What happens is that it starts to eat memory until it finaly quits... On memory warning i close and open database again, I have set cache size to 50 as mentioned in some posts here, and tried putting query into statement - same result.. it just garbles mamory and app quits after 300 inserts on iphone or somewhere around 900 inserts on iPad... Any help would be appreciated..

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• C#, cannot understand this error?

  - by 5YrsLaterDBA

  I am using VS2008. I have a project, SystemSoftware project, connect with a database and we are using L2E. I have a RuntimeInfo class which contains some shared information there. It looks like this: public class RuntimeInfo { public const int PWD_ExpireDays = 30; private static RuntimeInfo thisObj = new RuntimeInfo(); public static string AndeDBConnStr = ConfigurationManager.ConnectionStrings["AndeDBEntities"].ConnectionString; private RuntimeInfo() { } /// <summary> /// /// </summary> /// <returns>Return this singleton object</returns> public static RuntimeInfo getRuntimeInfo() { return thisObj; } } Now I added a helper project, AndeDataViewer, to the solution which creates a simple UI to display data from the database for testing/verification purpose. I don't want to create another set of Entity Data Model in the helper project. I just added all related files as a link in the new helper project. In the AndeDataViewer project, I get the connection string from above RuntimeInfo class which is a class from my SystemSoftware project as a linked file. The code in AndeDataViewer is like this: public class DbAccess : IDisposable { private String connStr = String.Empty; public DbAccess() { connStr = RuntimeInfo.AndeDBConnStr; } } My SystemSoftware works fine that means the RuntimeInfo class has no problem there. But when I run my AndeDataViewer, the statement inside above constructor, connStr = RuntimeInfo.AndeDBConnStr; , throws an exception. The exception is copied here: System.TypeInitializationException was unhandled Message="The type initializer for 'MyCompany.SystemSoftware.SystemInfo.RuntimeInfo' threw an exception." Source="AndeDataViewer" TypeName="MyCompany.SystemSoftware.SystemInfo.RuntimeInfo" StackTrace: at AndeDataViewer.DbAccess..ctor() in C:\workspace\SystemSoftware\Other\AndeDataViewer\AndeDataViewer\DbAccess.cs:line 17 at AndeDataViewer.Window1.rbRawData_Checked(Object sender, RoutedEventArgs e) in C:\workspace\SystemSoftware\Other\AndeDataViewer\AndeDataViewer\Window1.xaml.cs:line 69 at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) .... InnerException: System.NullReferenceException Message="Object reference not set to an instance of an object." Source="AndeDataViewer" StackTrace: at MyCompany.SystemSoftware.SystemInfo.RuntimeInfo..cctor() in C:\workspace\SystemSoftware\SystemSoftware\src\systeminfo\RuntimeInfo.cs:line 24 InnerException: I cannot understand this because it looks fine to me but why there is an exception? we cannot access static variable when a class is a linked class? A linked class should be the same as the local class I think. "Linked" here means when I add file I use "Add As Link".

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• Learning C, would appreciate input on why this solution works.

  - by Keifer

  This is literally the first thing I've ever written in C, so please feel free to point out all it's flaws. :) My issue, however is this: if I write the program the way I feel is cleanest, I get a broken program: #include <sys/queue.h> #include <stdlib.h> #include <stdio.h> #include <string.h> /* Removed prototypes and non related code for brevity */ int main() { char *cmd = NULL; unsigned int acct = 0; int amount = 0; int done = 0; while (done==0) { scanf ("%s %u %i", cmd, &acct, &amount); if (strcmp (cmd, "exit") == 0) done = 1; else if ((strcmp (cmd, "dep") == 0) || (strcmp (cmd, "deb") == 0)) debit (acct, amount); else if ((strcmp (cmd, "wd") == 0) || (strcmp (cmd, "cred") == 0)) credit (acct, amount); else if (strcmp (cmd, "fee") == 0) service_fee(acct, amount); else printf("Invalid input!\n"); } return(0); } void credit(unsigned int acct, int amount) { } void debit(unsigned int acct, int amount) { } void service_fee(unsigned int acct, int amount) { } As it stands, the above generates no errors at compile, but gives me a segfault when ran. I can fix this by changing the program to pass cmd by reference when calling scanf and strcmp. The segfault goes away and is replaced by warnings for each use of strcmp at compile time. Despite the warnings, the affected code works. warning: passing arg 1 of 'strcmp' from incompatible pointer type As an added bonus, modifying the scanf and strcmp calls allows the program to progress far enough to execute return(0), at which point the thing crashes with an Abort trap. If I swap out return(0) for exit(0) then everything works as expected. This leaves me with two questions: why was the original program wrong? How can I fix it better than I have? The bit about needing to use exit instead of return has me especially baffled.

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• Making a Wrapper class for ActiveMQ

  - by DarthVader

  I want to make a Wrapper class for ActiveMQ which will have only send and get functions. I want to wrap them in a static class. Users can use this client and send, get messages to the activemq instance. I want this process to be transparent. There are two classes in this link My only handicap is, i need to this in c++ and not sure where to start. I havent used c++ for ages and now not sure how I can create this wrapper class. I m giving it a try as follows: // .h file #include <stdlib.h> #include <iostream> using namespace std; class ActiveMQWrapper { public: static void send(std::string message); static std::string get(); }; // .cpp file #include<string> #include<iostream> #include "ActiveMQWrapper.h" void ActiveMQWrapper::send(std::string message){ std::cout<<message; } std::string ActiveMQWrapper::get(){ return "test"; } // test file #include <string> #include <iostream> #include "ActiveMQWrapper.h" int main() { std::string foo ="test"; ActiveMQWrapper::send(foo); std::cout<<ActiveMQWrapper::get(); return 1; } When I added the following to .h file, hell breaks loose. Do you think I should seperate this impl to a factory and initialize and instance and return to the wrapper above? How do i deal with all the dependencies? private: Connection* connection; Session* session; Destination* destination; MessageProducer* producer; int numMessages; bool useTopic; bool sessionTransacted; std::string brokerURI; and the header files, i get several messages as errors, which complains about the path. How can i get this correct? I eventually want to build a Factory, get an instance and send or get the messages to the queue. is there a code sample i can look into to get this right? essential i want to use the functionality of only this producer and consumer. Edit: I understand there is no such thing as static class in C++ . This is my reference.

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• With custom binding for Masonry how would I resize the container appropriately

  - by BigDubb

  Based on the suggestion give here, and the information given here on how to make a custom bindingHandler for a forEach, I decided to attempt to write my own custom binding for a forEach and Masonry. Because the elements are added on the fly the redrawing and moving around of elements to fill the space doesn't occur. So, this functionality needed to be moved after the elements have been rendered or called after each item has been added. Here is my bindingHandler ko.bindingHandlers.masonry = { init: function (element, valueAccessor, allBindingsAccessor) { var $element = $(element), originalContent = $element.html(); $element.data("original-content", originalContent); //var msnry = new Masonry($element); return { controlsDescendantBindings: true } }, update: function (element, valueAccessor, allBindingsAccessor) { var value = ko.utils.unwrapObservable(valueAccessor()), //get the list of items items = value.items(), //get a jQuery reference to the element $element = $(element), //get the current content of the element elementContent = $element.data("original-content"); $element.html(""); var container = $element[0]; var msnry = new Masonry(container); for (var index = 0; index < items.length; index++) { (function () { //get the list of items var item = ko.utils.unwrapObservable(items[index]), $childElement = $(elementContent); ko.applyBindings(item, $childElement[0]); //add the child to the parent $element.append($childElement); msnry.appended($childElement[0]); })(); msnry.layout(); msnry.bindResize(); } } }; and the HTML implementing the handler. <div id="criteriaContainer" data-bind="masonry: { items: SearchItems.Items }"> <div class="searchCriterion control-group"> <label class="control-label" data-bind="text: Description"></label> <div class="controls"> <input type="hidden" data-bind="value: Value, select2: { minimumInputLength: 3, queryUri: SearchUri(), placeholder: Placeholder(), allowClear: true }" style="width: 450px"> </div> <p data-bind="text: Value"></p> </div> </div> When this shows up on the page It stacks all if the elements rendered via the append method right on top of each other. You can see in my bindingHandler I am calling bindResize as well as layout(), neither of which seem to be having any effect. Here's a screenshot of what it looks like in the UI.

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• Several 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; Update Thank you for your answers, Eric Gunnerson and Aaronought. I'm afraid I haven't been able to articulate my questions well enough to attract very satisfying answers. The trouble is, I do know the answers to my questions on the surface, and I am, by no means, a newbie programmer. But I have to admit, a deeper understanding to the intricacies of how a language and its underlying platform/runtime handle storage of types has eluded me for as long as I've been a programmer, even though I write correct code.

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• Magento - How to select mysql rows by max value?

  - by Damodar Bashyal

  mysql> SELECT * FROM `log_customer` WHERE `customer_id` = 224 LIMIT 0, 30; +--------+------------+-------------+---------------------+-----------+----------+ | log_id | visitor_id | customer_id | login_at | logout_at | store_id | +--------+------------+-------------+---------------------+-----------+----------+ | 817 | 50139 | 224 | 2011-03-21 23:56:56 | NULL | 1 | | 830 | 52317 | 224 | 2011-03-27 23:43:54 | NULL | 1 | | 1371 | 136549 | 224 | 2011-11-16 04:33:51 | NULL | 1 | | 1495 | 164024 | 224 | 2012-02-08 01:05:48 | NULL | 1 | | 2130 | 281854 | 224 | 2012-11-13 23:44:13 | NULL | 1 | +--------+------------+-------------+---------------------+-----------+----------+ 5 rows in set (0.00 sec) mysql> SELECT * FROM `customer_entity` WHERE `entity_id` = 224; +-----------+----------------+---------------------------+----------+---------------------+---------------------+ | entity_id | entity_type_id | email | group_id | created_at | updated_at | +-----------+----------------+---------------------------+----------+---------------------+---------------------+ | 224 | 1 | [email protected] | 3 | 2011-03-21 04:59:17 | 2012-11-13 23:46:23 | +-----------+----------------+---------------------------+----------+--------------+----------+-----------------+ 1 row in set (0.00 sec) How can i search for customers who hasn't logged in for last 10 months and their account has not been updated for last 10 months. I tried below but failed. $collection = Mage::getModel('customer/customer')->getCollection(); $collection->getSelect()->joinRight(array('l'=>'log_customer'), "customer_id=entity_id AND MAX(l.login_at) <= '" . date('Y-m-d H:i:s', strtotime('10 months ago')) . "'")->group('e.entity_id'); $collection->addAttributeToSelect('*'); $collection->addFieldToFilter('updated_at', array( 'lt' => date('Y-m-d H:i:s', strtotime('10 months ago')), 'datetime'=>true, )); $collection->addAttributeToFilter('group_id', array( 'neq' => 5, )); Above tables have one customer for reference. I have no idea how to use MAX() on joins. Thanks UPDATE: This seems returning correct data, but I would like to do magento way using resource collection, so i don't need to do load customer again on for loop. $read = Mage::getSingleton('core/resource')->getConnection('core_read'); $sql = "select * from ( select e.*,l.login_at from customer_entity as e left join log_customer as l on l.customer_id=e.entity_id group by e.entity_id order by l.login_at desc ) as l where ( l.login_at <= '".date('Y-m-d H:i:s', strtotime('10 months ago'))."' or ( l.created_at <= '".date('Y-m-d H:i:s', strtotime('10 months ago'))."' and l.login_at is NULL ) ) and group_id != 5"; $result = $read->fetchAll($sql); I have loaded full shell script to github https://github.com/dbashyal/Magento-ecommerce-Shell-Scripts/blob/master/shell/suspendCustomers.php

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• iOs receivedData from NSURLConnection is nil

  - by yhl

  I was wondering if anyone could point out why I'm not able to capture a web reply. My NSLog shows that my [NSMutableData receivedData] has a length of 0 the entire run of the connection. The script that I hit when I click my login button returns a string. My NSLog result is pasted below, and after that I've pasted both the .h and .m files that I have. NSLog Result 2012-11-28 23:35:22.083 [12548:c07] Clicked on button_login 2012-11-28 23:35:22.090 [12548:c07] theConnection is succesful 2012-11-28 23:35:22.289 [12548:c07] didReceiveResponse 2012-11-28 23:35:22.290 [12548:c07] didReceiveData 2012-11-28 23:35:22.290 [12548:c07] 0 2012-11-28 23:35:22.290 [12548:c07] connectionDidFinishLoading 2012-11-28 23:35:22.290 [12548:c07] 0 ViewController.h #import <UIKit/UIKit.h> @interface ViewController : UIViewController // Create an Action for the button. - (IBAction)button_login:(id)sender; // Add property declaration. @property (nonatomic,assign) NSMutableData *receivedData; @end ViewController.m #import ViewController.h @interface ViewController () @end @implementation ViewController @synthesize receivedData; - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { NSLog(@"didReceiveResponse"); [receivedData setLength:0]; } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { NSLog(@"didReceiveData"); [receivedData appendData:data]; NSLog(@"%d",[receivedData length]); } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { NSLog(@"connectionDidFinishLoading"); NSLog(@"%d",[receivedData length]); } - (IBAction)button_login:(id)sender { NSLog(@"Clicked on button_login"); NSString *loginScriptURL = [NSString stringWithFormat:@"http://www.website.com/app/scripts/login.php?"]; NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:loginScriptURL]]; NSString *postString = [NSString stringWithFormat:@"&paramUsername=user&paramPassword=pass"]; NSData *postData = [postString dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES]; [theRequest setHTTPMethod:@"POST"]; [theRequest setHTTPBody:postData]; // Create the actual connection using the request. NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; // Capture the response if (theConnection) { NSLog(@"theConnection is succesful"); } else { NSLog(@"theConnection failed"); } } @end

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• Could not load file or assembly ... or one of its dependencies. An attempt was made to load a progra

  - by Dan

  I am getting the following error message when compiling or attempting to run my application on Windows 7 64 bit. I've scoured the internet and many people have the same error message however none of the solutions address my problem or situation. Using VS 2010. Error 38 Could not load file or assembly 'file:///D:/Projects/Windows Projects/Weld/Components/FileAttachments/FileAttachments/FileAttachments/bin/x86/Debug/FileAttaching.dll' or one of its dependencies. An attempt was made to load a program with an incorrect format. Line 1212, position 5. D:\Projects\Windows Projects\Weld\Weld\Weld.UI\frmMain.resx 1212 5 Weld.UI Ok, so I have 2 projects a UI project and a FileAttachment project. UI project has a reference to FileAttachment project. When I compile UI project in "Any CPU" mode everything works fine and it runs. I assume 'Any CPU' will run in 64bit mode when I compile as that is the platform I am using. I want to run/compile as x86 so I try to do that, so I change configuration for all projects to x86 and verify that these configurations are compiling to x86. I compile and get the error as stated above. I find it odd that it compiles and works fine in 64bit but not 32bit. However when compiled and deployed to users as 'Any CPU', if these users have x86 it still works for them no problem. I just can't compile or run as x86 on my PC. Again, I can compile as Any CPU and deploy to a 32bit PC no problem. Neither project are referencing any 64bit only dlls. Both projects are verified to be targetting 32bit dll's and .NET Framework assemblies. I need to compile and run this locally under 32bit mode. I need JIT edit/continue among other things. Here is the line of code in the resx file that is causing the problem: </data> <data name="Appearance17.Image" type="System.Drawing.Bitmap, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64"> <value> The resx file is verified to be generated for .NET 2.0 amnd is only referencing .NET 2.0 assemblies and not .NET 4.0 versions. Any ideas here? I've searched the net and have found hundreds of people with the same error message but a different problem.

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• Yii Many_Many Relationship and Form

  - by Thorpe Obazee

  // Post model return array( 'categories' => array(self::HAS_MANY, 'Category', 'posts_categories(post_id, category_id)') ); I already have the setup of tables posts id, title, content categories id, name posts_categories post_id, category_i The problem I have is that I am getting an error when creating this form: <?php $form=$this->beginWidget('CActiveForm', array( 'id'=>'post-form', 'enableAjaxValidation'=>false, )); ?> <p class="note">Fields with <span class="required">*</span> are required.</p> <?php echo $form->errorSummary($model); ?> <div class="row"> <?php echo $form->labelEx($model,'title'); ?> <?php echo $form->textField($model,'title',array('size'=>60,'maxlength'=>255)); ?> <?php echo $form->error($model,'title'); ?> </div> <div class="row"> <?php echo $form->labelEx($model,'uri'); ?> <?php echo $form->textField($model,'uri',array('size'=>60,'maxlength'=>255)); ?> <?php echo $form->error($model,'uri'); ?> </div> <div class="row"> <?php echo $form->labelEx($model,'content'); ?> <?php echo $form->textArea($model,'content',array('rows'=>6, 'cols'=>50)); ?> <?php echo $form->error($model,'content'); ?> </div> <div class="row"> <?php // echo $form->labelEx($model,'content'); ?> <?php echo CHtml::activeDropDownList($model,'category_id', CHtml::listData(Category::model()->findAll(), 'id', 'name')); ?> <?php // echo $form->error($model,'content'); ?> </div> <div class="row buttons"> <?php echo CHtml::submitButton($model->isNewRecord ? 'Create' : 'Save'); ?> </div> <?php $this->endWidget(); ?> The error is: Property "Post.category_id" is not defined. I am quite confused. What should I be doing to correct this?

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• Communicate progress from local Service

  - by kpdvx

  An application I'm building uses a local Service for downloading files from the web to the phone's SD card. In this app users can browse lists of books, and read them while online. A user can also download a pdf copy of a book for offline viewing. To handle downloads I'm using a locally bound Service. I do not want this Service to run all the time, only when downloading files. So that the Service can shut itself down when its tasks are complete, I am not binding to the service, rather I'm sending an "enqueue for download" command through the Intent passed to Context.startService. Books available for download are shown in a list. A user can choose to download a book by clicking on its row in the list. On download, I need to show download progress using a ProgressBar on the actual book list row. I need to also show, on the rows, if a book is enqueued for download, or if its download has completed or failed. The books can be shown in different activities throughout the application--in search, or in the user's list of favorite books, for example. When the books are shown in different places, these are not the same objects, but they are uniquely identified by their bookId. Because I do not want to bind to the service from every Activity, my tentative plan was to use a public static final HashMap on the Service class itself to contain a mapping of bookId to download status, an enum of enqueued, downloading, cancelled, etc. Each book view, when displayed, would check this static HashMap, and if the bookId is in the map, retrieve and display its status. I don't particularly like this idea, but at the moment it's the only way I can think of to retrieve status from the Service without having to bind to it and start it. Additionally I need to retrieve download progress percent from the Service, for a given bookId, if it is the active download. Again I'd rather not bind to the service from every activity, so I'm not sure how to go about retrieving current progress from the Service. My current plan is to use some sort of singleton mediator, that the Service will push updates to, and the views can read from. But I'm not terribly happy with this idea. The reason I'd like to avoid binding to the Service from each Activity is 1.) I'm already running another Service and 2.) binding is verbose and I'd like to avoid needing to pass around a reference to the Service (but admittedly this isn't too much of a problem). Perhaps binding to the local Service isn't expensive enough to warrant this other setup? Should I not be concerned about binding to it from each Activity? Maybe this is a non-issue?

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• How does the CLR (.NET) internally allocate and pass around custom value types (structs)?

  - by stakx

  Question: Do all CLR value types, including user-defined structs, live on the evaluation stack exclusively, meaning that they will never need to be reclaimed by the garbage-collector, or are there cases where they are garbage-collected? Background: I have previously asked a question on SO about the impact that a fluent interface has on the runtime performance of a .NET application. I was particuarly worried that creating a large number of very short-lived temporary objects would negatively affect runtime performance through more frequent garbage-collection. Now it has occured to me that if I declared those temporary objects' types as struct (ie. as user-defined value types) instead of class, the garbage collector might not be involved at all if it turns out that all value types live exclusively on the evaluation stack. What I've found out so far: I did a brief experiment to see what the differences are in the CIL generated for user-defined value types and reference types. This is my C# code: struct SomeValueType { public int X; } class SomeReferenceType { public int X; } . . static void TryValueType(SomeValueType vt) { ... } static void TryReferenceType(SomeReferenceType rt) { ... } . . var vt = new SomeValueType { X = 1 }; var rt = new SomeReferenceType { X = 2 }; TryValueType(vt); TryReferenceType(rt); And this is the CIL generated for the last four lines of code: .locals init ( [0] valuetype SomeValueType vt, [1] class SomeReferenceType rt, [2] valuetype SomeValueType <>g__initLocal0, // [3] class SomeReferenceType <>g__initLocal1, // why are these generated? [4] valuetype SomeValueType CS$0$0000 // ) L_0000: ldloca.s CS$0$0000 L_0002: initobj SomeValueType // no newobj required, instance already allocated L_0008: ldloc.s CS$0$0000 L_000a: stloc.2 L_000b: ldloca.s <>g__initLocal0 L_000d: ldc.i4.1 L_000e: stfld int32 SomeValueType::X L_0013: ldloc.2 L_0014: stloc.0 L_0015: newobj instance void SomeReferenceType::.ctor() L_001a: stloc.3 L_001b: ldloc.3 L_001c: ldc.i4.2 L_001d: stfld int32 SomeReferenceType::X L_0022: ldloc.3 L_0023: stloc.1 L_0024: ldloc.0 L_0025: call void Program::TryValueType(valuetype SomeValueType) L_002a: ldloc.1 L_002b: call void Program::TryReferenceType(class SomeReferenceType) What I cannot figure out from this code is this: Where are all those local variables mentioned in the .locals block allocated? How are they allocated? How are they freed? Why are so many anonymous local variables needed and copied to-and-fro only to initialize my two local variables rt and vt?

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• C problem, left of '->' must point to class/struct/union/generic type ??

  - by Patrick

  Hello! Trying to understand why this doesn't work. I keep getting the following errors: left of '-nextNode' must point to class/struct/union/generic type (Also all the lines with a - in the function new_math_struct) Header file #ifndef MSTRUCT_H #define MSTRUCT_H #define PLUS 0 #define MINUS 1 #define DIVIDE 2 #define MULTIPLY 3 #define NUMBER 4 typedef struct math_struct { int type_of_value; int value; int sum; int is_used; struct math_struct* nextNode; } ; typedef struct math_struct* math_struct_ptr; #endif C file int get_input(math_struct_ptr* startNode) { /* character, input by the user */ char input_ch; char* input_ptr; math_struct_ptr* ptr; math_struct_ptr* previousNode; input_ptr = &input_ch; previousNode = startNode; /* as long as input is not ok */ while (1) { input_ch = get_input_character(); if (input_ch == ',') // Carrage return return 1; else if (input_ch == '.') // Illegal character return 0; if (input_ch == '+') ptr = new_math_struct(PLUS, 0); else if (input_ch == '-') ptr = new_math_struct(MINUS, 0); else if (input_ch == '/') ptr = new_math_struct(DIVIDE, 0); else if (input_ch == '*') ptr = new_math_struct(MULTIPLY, 0); else ptr = new_math_struct(NUMBER, atoi(input_ptr)); if (startNode == NULL) { startNode = previousNode = ptr; } else { previousNode->nextNode = ptr; previousNode = ptr; } } return 0; } math_struct_ptr* new_math_struct(int symbol, int value) { math_struct_ptr* ptr; ptr = (math_struct_ptr*)malloc(sizeof(math_struct_ptr)); ptr->type_of_value = symbol; ptr->value = value; ptr->sum = 0; ptr->is_used = 0; return ptr; } char get_input_character() { /* character, input by the user */ char input_ch; /* get the character */ scanf("%c", &input_ch); if (input_ch == '+' || input_ch == '-' || input_ch == '*' || input_ch == '/' || input_ch == ')') return input_ch; // A special character else if (input_ch == '\n') return ','; // A carrage return else if (input_ch < '0' || input_ch > '9') return '.'; // Not a number else return input_ch; // Number } The header for the C file just contains a reference to the struct header and the definitions of the functions. Language C.

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