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  • eclipse error with android: id cannot be resolved or is not a field

    - by Jaynathan Leung
    Hi, I just started playing around with android development, and already with just an attempt at making a button, I have encountered a problem. The error I'm given in the following code is right on "R.id.button1". It says id cannot be resolved or is not a field. Do I need to manually reference every single object I make in the layout xml file? I found that this did work, but it does seem to be a bit much for every button I want to make... package com.example.helloandroid; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; public class HelloAndroid extends Activity { /** Called when the activity is first created. */ private Button button1; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); button1 = (Button)findViewById(R.id.button1); button1.setOnClickListener(new OnClickListener() { public void onClick(View v) { finish(); } }); } }

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  • Magic Method __set() on a Instantiated Object

    - by streetparade
    Ok i have a problem, sorry if i cant explaint it clear but the code speaks for its self. i have a class which generates objects from a given class name; Say we say the class is Modules: public function name($name) { $this->includeModule($name); try { $module = new ReflectionClass($name); $instance = $module->isInstantiable() ? $module->newInstance() : "Err"; $this->addDelegate($instance); } catch(Exception $e) { Modules::Name("Logger")->log($e->getMessage()); } return $this; } The AddDelegate Method: protected function addDelegate($delegate) { $this->aDelegates[] = $delegate; } The __call Method public function __call($methodName, $parameters) { $delegated = false; foreach ($this->aDelegates as $delegate) { if(class_exists(get_class($delegate))) { if(method_exists($delegate,$methodName)) { $method = new ReflectionMethod(get_class($delegate), $methodName); $function = array($delegate, $methodName); return call_user_func_array($function, $parameters); } } } The __get Method public function __get($property) { foreach($this->aDelegates as $delegate) { if ($delegate->$property !== false) { return $delegate->$property; } } } All this works fine expect the function __set public function __set($property,$value) { //print_r($this->aDelegates); foreach($this->aDelegates as $k=>$delegate) { //print_r($k); //print_r($delegate); if (property_exists($delegate, $property)) { $delegate->$property = $value; } } //$this->addDelegate($delegate); print_r($this->aDelegates); } class tester { public function __set($name,$value) { self::$module->name(self::$name)->__set($name,$value); } } Module::test("logger")->log("test"); // this logs, it works echo Module::test("logger")->path; //prints /home/bla/test/ this is also correct But i cant set any value to class log like this Module::tester("logger")->path ="/home/bla/test/log/"; The path property of class logger is public so its not a problem of protected or private property access. How can i solve this issue? I hope i could explain my problem clear.

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  • Why doesn't this CompiledQuery give a performance improvement?

    - by Grammarian
    I am trying to speed up an often used query. Using a CompiledQuery seemed to be the answer. But when I tried the compiled version, there was no difference in performance between the compiled and non-compiled versions. Can someone please tell me why using Queries.FindTradeByTradeTagCompiled is not faster than using Queries.FindTradeByTradeTag? static class Queries { // Pre-compiled query, as per http://msdn.microsoft.com/en-us/library/bb896297 private static readonly Func<MyEntities, int, IQueryable<Trade>> mCompiledFindTradeQuery = CompiledQuery.Compile<MyEntities, int, IQueryable<Trade>>( (entities, tag) => from trade in entities.TradeSet where trade.trade_tag == tag select trade); public static Trade FindTradeByTradeTagCompiled(MyEntities entities, int tag) { IQueryable<Trade> tradeQuery = mCompiledFindTradeQuery(entities, tag); return tradeQuery.FirstOrDefault(); } public static Trade FindTradeByTradeTag(MyEntities entities, int tag) { IQueryable<Trade> tradeQuery = from trade in entities.TradeSet where trade.trade_tag == tag select trade; return tradeQuery.FirstOrDefault(); } }

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  • How to load/save C++ class instance (using STL containers) to disk

    - by supert
    I have a C++ class representing a hierarchically organised data tree which is very large (~Gb, basically as large as I can get away with in memory). It uses an STL list to store information at each node plus iterators to other nodes. Each node has only one parent, but 0-10 children. Abstracted, it looks something like: struct node { public: node_list_iterator parent; // iterator to a single parent node double node_data_array[X]; map<int,node_list_iterator> children; // iterators to child nodes }; class strategy { private: list<node> tree; // hierarchically linked list of nodes struct some_other_data; public: void build(); // build the tree void save(); // save the tree from disk void load(); // load the tree from disk void use(); // use the tree }; I would like to implement the load() and save() to disk, and it should be fairly fast, however the obvious problems are: I don't know the size in advance; The data contains iterators, which are volatile; My ignorance of C++ is prodigious. Could anyone suggest a pure C++ solution please?

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  • Can JMX operations take interfaces as parameters?

    - by Thor84no
    I'm having problems with an MBean that takes a Map<String, Object> as a parameter. If I try to execute it via JMX using a proxy object, I get an Exception: Caused by: javax.management.ReflectionException at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:231) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) Caused by: java.lang.IllegalArgumentException: Unable to find operation updateProperties(java.util.HashMap) It appears that it attempts to use the actual implementation class rather than the interface, and doesn't check if this is a child of the required interface. The same thing happens for extended classes (for example declare HashMap, pass in LinkedHashMap). Does this mean it's impossible to use an interface for such methods? At the moment I'm getting around it by changing the method signature to accept a HashMap, but it seems odd that I wouldn't be able to use interfaces (or extended classes) in my MBeans. Edit: The proxy object is being created by an in-house utility class called JmxInvocationHandler. The (hopefully) relevant parts of it are as follows: public class JmxInvocationHandler implements InvocationHandler { ... public static <T> T createMBean(final Class<T> iface, SFSTestProperties properties, String mbean, int shHostID) { T newProxyInstance = (T) Proxy.newProxyInstance(iface.getClassLoader(), new Class[] { iface }, (InvocationHandler) new JmxInvocationHandler(properties, mbean, shHostID)); return newProxyInstance; } ... private JmxInvocationHandler(SFSTestProperties properties, String mbean, int shHostID) { this.mbeanName = mbean + MBEAN_SUFFIX + shHostID; msConfig = new MsConfiguration(properties.getHost(0), properties.getMSAdminPort(), properties.getMSUser(), properties.getMSPassword()); } ... public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if (management == null) { management = ManagementClientStore.getInstance().getManagementClient(msConfig.getHost(), msConfig.getAdminPort(), msConfig.getUser(), msConfig.getPassword(), false); } final Object result = management.methodCall(mbeanName, method.getName(), args == null? new Object[] {} : args); return result; } }

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  • ExecuteNonQuery: Connection property has not been initialized

    - by 20151012
    I get an error in my code: The error point at dbcom.ExecuteNonQuery();. Code(connection) public admin_addemp() { InitializeComponent(); con = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\EMPS.accdb;Persist Security Info=True"); con.Open(); ds.Tables.Add(dt); ds.Tables.Add(dt2); } Code (Save button) private void save_btn_Click(object sender, EventArgs e) { OleDbCommand check = new OleDbCommand(); check.Connection = con; check.CommandText = "SELECT COUNT(*) FROM employeeDB WHERE ([EmployeeName]=?)"; check.Parameters.AddWithValue("@EmployeeName", tb_name.Text); if (Convert.ToInt32(check.ExecuteScalar()) == 0) { dbcom2 = new OleDbCommand("SELECT EmployeeID FROM employeeDB WHERE EmployeeID='" + tb_id.Text + "'", con); OleDbParameter param = new OleDbParameter(); param.ParameterName = tb_id.Text; dbcom.Parameters.Add(param); OleDbDataReader read = dbcom2.ExecuteReader(); if (read.HasRows) { MessageBox.Show("The Employee ID '" + tb_id.Text + "' already exist. Please choose another Employee ID."); read.Dispose(); read.Close(); } else { string q = "INSERT INTO employeeDB (EmployeeID, EmployeeName, IC, Address, State, " + " Postcode, DateHired, Phone, ManagerName) VALUES ('" + tb_id.Text + "', " + " '" + tb_name.Text + "', '" + tb_ic.Text + "', '" + tb_add1.Text + "', '" + cb_state.Text + "', " + " '" + tb_postcode.Text + "', '" + dateTimePicker1.Value + "', '" + tb_hp.Text + "', '" + cb_manager.Text + "')"; dbcom = new OleDbCommand(q, con); dbcom.ExecuteNonQuery(); MessageBox.Show("New Employee '" + tb_name.Text + "'- Successfuly Added."); } } else { MessageBox.Show("Employee name '" + tb_name.Text + "' already added into the database"); } ds.Dispose(); } I'm using Microsoft Access 2010 as my database and this is stand alone system. Please help me.

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  • Serialization of Queue type not working

    - by Soham
    Consider this piece of code: private Queue Date=new Queue(); //other declarations public DateTime _Date { get { return (DateTime)Date.Peek();} set { Date.Enqueue(value); } } //other properties and stuff.... public void UpdatePosition(...) { //other code IFormatter formatter = new BinaryFormatter(); Stream Datestream = new MemoryStream(); formatter.Serialize(Datestream, Date); byte[] Datebin = new byte[2048]; Datestream.Read(Datebin,0,2048); //Debug-Bug Console.WriteLine(Convert.ToString(this._Date)); Console.WriteLine(BitConverter.ToString(Datebin, 0, 3)); //other code } The output of the first WriteLine is perfect. I.e to check if really the Queue is initialised or not. It is. The right variables are stored etc. (I inserted a value in that Queue, that part of the code is not shown.) But the second WriteLine is not giving the right expected answer: It serializes the entire Queue to 00-00-00.

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  • Custom ASP.net UserControl List<T> Property, having trouble setting declaratively

    - by Chris McCall
    I'm developing a custom UserControl to inject JQuery hotkeys into a page declaratively on the server side. Here's the control (the important parts anyway): [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal), AspNetHostingPermission(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal), DefaultProperty("HotKeys"), ParseChildren(true, "HotKeys"), ToolboxData("<{0}:HotKeysControl runat=\"server\"> </{0}:HotKeysControl>")] public partial class HotKeysControl : System.Web.UI.WebControls.WebControl { private string crlf = Environment.NewLine; public List<HotKey> _HotKeys; public HotKeysControl() { if (_HotKeys == null) { _HotKeys = new List<HotKey>(); } // if I uncomment this line, script is injected into the page // _HotKeys.Add(new HotKey("ctrl+r","thisControl")); } [ Category("Behavior"), Description("The hotkeys collection"), DesignerSerializationVisibility( DesignerSerializationVisibility.Content), Editor(typeof(HotKeyCollectionEditor), typeof(UITypeEditor)), PersistenceMode(PersistenceMode.InnerDefaultProperty) ] public List<HotKey> HotKeys { set { _HotKeys = value; } get { return _HotKeys; } } Here's the .aspx code: <%@ Register Assembly="MyCompany.ProductName.WebControls" Namespace="MyCompany.ProductName.WebControls" TagPrefix="uc" %> ... <uc:HotKeysControl ID="theHotkeys" runat="server" Visible="false"> <uc:HotKey ControlName="firstControl" KeyCode="ctrl+1" /> <uc:HotKey ControlName="thirdControl" KeyCode="ctrl+2" /> </uc:HotKeysControl> Nothing happens, as if no HotKeys objects are being added to the property collection. What Am I doing wrong? If I uncomment out the line above and "manually" add items, it works. It's something about how I'm declaratively adding hotkeys to the page. Any ideas?

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  • Why is only the first shown window focusable

    - by Miha Markic
    Imagine the code below. Only the first window appears on the top, all of subsequent windows won't nor can they be programatically focused for some reason (they appear in the background). Any idea how to workaround this? BTW, static methods/properties are not allowed nor is any global property. [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Thread t1 = new Thread(CreateForm); t1.SetApartmentState(ApartmentState.STA); t1.Start(); t1.Join(); t1 = new Thread(CreateForm); t1.SetApartmentState(ApartmentState.STA); t1.Start(); t1.Join(); } private static void CreateForm() { using (Form f = new Form()) { System.Windows.Forms.Timer t = new System.Windows.Forms.Timer { Enabled = true, Interval = 2000 }; t.Tick += (s, e) => { f.Close(); t.Enabled = false; }; f.TopMost = true; Application.Run(f); } }

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  • Could this be considered a well-written PHP5 class?

    - by Ben Dauphinee
    I have been learning OOP principals on my own for a while, and taken a few cracks at writing classes. What I really need to know now is if I am actually using what I have learned correctly, or if I could improve as far as OOP is concerned. I have chopped a massive portion of code out of a class that I have been working on for a while now, and pasted it here. To all you skilled and knowledgeable programmers here I ask: Am I doing it wrong? class acl extends genericAPI{ // -- Copied from genericAPI class protected final function sanityCheck($what, $check, $vars){ switch($check){ case 'set': if(isset($vars[$what])){return(1);}else{return(0);} break; } } // --------------------------------- protected $db = null; protected $dataQuery = null; public function __construct(Zend_Db_Adapter_Abstract $db, $config = array()){ $this->db = $db; if(!empty($config)){$this->config = $config;} } protected function _buildQuery($selectType = null, $vars = array()){ // Removed switches for simplicity sake $this->dataQuery = $this->db->select( )->from( $this->config['table_users'], array('tf' => '(CASE WHEN count(*) > 0 THEN 1 ELSE 0 END)') )->where( $this->config['uidcol'] . ' = ?', $vars['uid'] ); } protected function _sanityRun_acl($sanitycheck, &$vars){ switch($sanitycheck){ case 'uid_set': if(!$this->sanityCheck('uid', 'set', $vars)){ throw new Exception(ERR_ACL_NOUID); } $vars['uid'] = settype($vars['uid'], 'integer'); break; } } private function user($action = null, $vars = array()){ switch($action){ case 'exists': $this->_sanityRun_acl('uid_set', $vars); $this->_buildQuery('user_exists_idcheck', $vars); return($this->db->fetchOne($this->dataQuery->__toString())); break; } } public function user_exists($uid){ return($this->user('exists', array('uid' => $uid))); } } $return = $acl_test->user_exists(1);

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  • Silverlight Not Rendering On Navigation

    - by Azmath
    I'm trying to create a site that requires login. Its entirely designed in silverlight. So my first page, home.xaml loads in mysite.aspx and it basically has a login page. AFter login, the user is redirected to another page user.aspx. in that page, i've embedded another silverlight control called nav.xaml. so now when user.aspx loads it is supposed to load a silverlight control. i've programmed app.xaml.vb such that it loads nav.xaml in the rootlayout when the page requesting is user.aspx. but for some reason its not working. my app.xaml.vb code: Private Sub Application_Startup(ByVal o As Object, ByVal e As StartupEventArgs) Handles Me.Startup If e.InitParams.ContainsKey("ReqPage") Then If e.InitParams("ReqPage") = "userpage" Then Me.RootVisual = New Nav() End If Else Me.RootVisual = New Home() End If End Sub in IE, half of the nav.xaml is rendered. but in firefox nothing is rendered. so wats going on exactly? pls help!

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  • No operations allowed after statement closed issue

    - by Washu
    I have the next methods in my singleton to execute the JDBC connections public void openDB() throws ClassNotFoundException, IllegalAccessException, InstantiationException, SQLException { Class.forName("com.mysql.jdbc.Driver").newInstance(); String url = "jdbc:mysql://localhost/mbpe_peru";//mydb conn = DriverManager.getConnection(url, "root", "admin"); st = conn.createStatement(); } public void sendQuery(String query) throws SQLException { st.executeUpdate(query); } public void closeDB() throws SQLException { st.close(); conn.close(); } And I'm having a problem in a void where i have to call this twice. private void jButton1ActionPerformed(ActionEvent evt) { Main.getInstance().openDB(); Main.getInstance().sendQuery("call insertEntry('"+EntryID()+"','"+SupplierID()+"');"); Main.getInstance().closeDB(); Main.getInstance().openDB(); for(int i=0;i<dataBox.length;i++){ Main.getInstance().sendQuery("call insertCount('"+EntryID()+"','"+SupplierID()+"','"+BoxID()+"'); Main.getInstance().closeDB(); } } I have already tried to keep the connection open and send the 2 querys and after that closed and it didnt work... The only way it worked was to not use the methods, declare the commands for the connection and use different variables for the connection and the statement. I thought that if i close the Connecion and the Statement I could use the variable once again since is a method but I'm not able to. Is there any way to solve this using my methods for the JDBC connection?

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  • OnClickListener on Tabs not working

    - by Aracos
    Greetings, I am trying to get the Click - event when clicking on the currently selected tab of my TabActivity. The onTabChangedHandler is only called whenever the tab is changed, not if the currently active Tab is clicked. The debugger tells me i have the onClickListener Registered for the TabWidget within my TabHost. Am i registering for the wrong View? Also, I am unable to create a Context Menu for the Tabs, only for its content, is this problem related? public class TestDroidViewTab extends TabActivity implements TabContentFactory , OnTabChangeListener, OnClickListener { private static final String LOG_KEY = "TEST"; ListView listView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); final TabHost tabHost = getTabHost(); TabHost.TabSpec ts = tabHost.newTabSpec("ID_1"); ts.setIndicator("1"); ts.setContent(this); tabHost.addTab(ts); ts = tabHost.newTabSpec("ID_2"); ts.setIndicator("2"); ts.setContent(this); tabHost.addTab(ts); ts = tabHost.newTabSpec("ID_3"); ts.setIndicator("3"); ts.setContent(this); tabHost.addTab(ts); tabHost.setOnClickListener(this); tabHost.setOnTabChangedListener(this); } public void onClick(View v) { Log.d(LOG_KEY, "OnClick"); } public void onTabChanged(String tabId) { Log.d(LOG_KEY, "OnTabChanged"); }

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  • C# array of objects - conditional validation

    - by fishdump
    Sorry about the vague title! I have an class with a number of member variables (system, zone, site, ...) public sealed class Cello { public String Company; public String Zone; public String System; public String Site; public String Facility; public String Process; //... } I have an array of objects of this class. private Cello[] m_cellos = null; // ... I need to know whether the array contains objects with the same site but different systems, zones or companies since such a situation would be illegal. I have various other checks to make but they are all along similar lines. The Array class has a number of functions that look promising but I am not very up on defining 'key selector' functions and things like that. Any suggestions or pointers would be greatly appreciated. --- Alistair.

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  • Run code before class instanciation in ActionScript 3

    - by soow.fr
    I need to run code in a class declaration before its instanciation. This would be especially useful to automatically register classes in a factory. See: // Main.as public class Main extends Sprite { public function Main() : void { var o : Object = Factory.make(42); } } // Factory.as public class Factory { private static var _factory : Array = new Array(); public static function registerClass(id : uint, c : Class) : void { _factory[id] = function () : Object { return new c(); }; } public static function make(id : uint) : Object { return _factory[id](); } } // Foo.as public class Foo { // Run this code before instanciating Foo! Factory.registerClass(42, Foo); } AFAIK, the JIT machine for the ActionScript language won't let me do that since no reference to Foo is made in the Main method. The Foo class being generated, I can't (and don't want to) register the classes in Main: I'd like to register all the exported classes in a specific package (or library). Ideally, this would be done through package introspection, which doesn't exist in ActionScript 3. Do you know any fix (or other solution) to my design issue?

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  • How to Implement an Interface that Requires Duplicate Member Names in C#?

    - by Will Marcouiller
    I often have to implement some interfaces such as IEnumerable<T> in my code. Each time, when implementing automatically, I encounter the following: public IEnumerator<T> GetEnumerator() { // Code here... } public IEnumerator GetEnumerator1() { // Code here... } Though I have to implement both GetEnumerator() methods, they impossibly can have the same name, even if we understand that they do the same, somehow. The compiler can't treat them as one being the overload of the other, because only the return type differs. When doing so, I manage to set the GetEnumerator1() accessor to private. This way, the compiler doesn't complaint about not implementing the interface member, and I simply throw a NotImplementedException within the methods body. However, I wonder whether it is a good practice, or if I shall proceed differently, as perhaps a method alias or something like so. What is the best approach while implementing an interface such as IEnumerable<T> that requires the implementation of two different methods with the same name?

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  • Implementing Unowned relationship Google App Engine

    - by nwallman
    My question is more of a best practices question on how to implement unowned relationships with Google App Engine. I am using JDO to do my persistence and like recommended in the google docs I'm persisting my list of unowned relationships like so: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class User implements Serializable, UserDetails { ... @Persistent private List<Key> groups; ... } Now I came across my predicament when I went to query that list of objects using they Key object. So when I get my list of group keys in order to actually return a list of Group objects I have to do a look up on that key to get the object. My question is what is the recommended way of doing a unowned look up on a model object? Should I have an instance of the PersistanceManagerFactory on my Model object so I can do a lookup? Should I have an instance of my GroupDAO object on my Model object so I can do a look up? Should I have a Utility to do this type of lookup? I'm new to this so I just want to know which is the best way to do this. Thanks.

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  • Splitting Code into Headers/Source files

    - by cam
    I took the following code from the examples page on Asio class tcp_connection : public boost::enable_shared_from_this<tcp_connection> { public: typedef boost::shared_ptr<tcp_connection> pointer; static pointer create(boost::asio::io_service& io_service) { return pointer(new tcp_connection(io_service)); } tcp::socket& socket() { return socket_; } void start() { message_ = make_daytime_string(); boost::asio::async_write(socket_, boost::asio::buffer(message_), boost::bind(&tcp_connection::handle_write, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); } private: tcp_connection(boost::asio::io_service& io_service) : socket_(io_service) { } void handle_write(const boost::system::error_code& /*error*/, size_t /*bytes_transferred*/) { } tcp::socket socket_; std::string message_; }; I'm relatively new to C++ (from a C# background), and from what I understand, most people would split this into header and source files (declaration/implementation, respectively). Is there any reason I can't just leave it in the header file if I'm going to use it across many source files? If so, are there any tools that will automatically convert it to declaration/implementation for me? Can someone show me what this would look like split into header/source file for an example (or just part of it, anyway)? I get confused around weird stuff like thistypedef boost::shared_ptr<tcp_connection> pointer; Do I include this in the header or the source? Same with tcp::socket& socket() I've read many tutorials, but this has always been something that has confused me about C++.

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  • Best practice for debug Asserts during Unit testing

    - by Steve Steiner
    Does heavy use of unit tests discourage the use of debug asserts? It seems like a debug assert firing in the code under test implies the unit test shouldn't exist or the debug assert shouldn't exist. "There can be only one" seems like a reasonable principle. Is this the common practice? Or do you disable your debug asserts when unit testing, so they can be around for integration testing? Edit: I updated 'Assert' to debug assert to distinguish an assert in the code under test from the lines in the unit test that check state after the test has run. Also here is an example that I believe shows the dilema: A unit test passes invalid inputs for a protected function that asserts it's inputs are valid. Should the unit test not exist? It's not a public function. Perhaps checking the inputs would kill perf? Or should the assert not exist? The function is protected not private so it should be checking it's inputs for safety.

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  • Will this cause a problem with different runtimes with DLL?

    - by Milo
    My gui application supports polymorphic timed events so that means that the user calls new, and the gui calls delete. This can create a problem if the runtimes are incompatible. So I was told a proposed solution would be this: class base; class Deallocator { void operator()(base* ptr) { delete ptr; } } class base { public: base(Deallocator dealloc) { m_deleteFunc = dealloc; } ~base() { m_deleteFunc(this); } private: Deallocator m_deleteFunc; } int main { Deallocator deletefunc; base baseObj(deletefunc); } While this is a good solution, it does demand that the user create a Deallocator object which I do not want. I was however wondering if I provided a Deallocator to each derived class: eg class derived : public base { Deallocator dealloc; public: Derived() : base(dealloc); { } }; I think this still does not work though. The constraint is that: The addTimedEvent() function is part of the Widget class which is also in the dll, but it is instanced by the user. The other constraint is that some classes which derive from Widget call this function with their own timed event classes. Given that "he who called new must call delete" what could work given these constraints? Thanks

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  • Query Parameter Value Is Null When Enum Item 0 is Cast with Int32

    - by Timothy
    When I use the first item in a zero-based Enum cast to Int32 as a query parameter, the parameter value is null. I've worked around it by simply setting the first item to a value of 1, but I was wondering though what's really going on here? This one has me scratching my head. Why is the parameter value regarded as null, instead of 0? Enum LogEventType : int { SignIn, SignInFailure, SignOut, ... } private static DataTable QueryEventLogSession(DateTime start, DateTime stop) { DataTable entries = new DataTable(); using (FbConnection conn = new FbConnection(DSN)) { using (FbDataAdapter adapter = new FbDataAdapter( "SELECT event_type, event_timestamp, event_details FROM event_log " + "WHERE event_timestamp BETWEEN @start AND @stop " + "AND event_type IN (@signIn, @signInFailure, @signOut) " + "ORDER BY event_timestamp ASC", conn)) { adapter.SelectCommand.Parameters.AddRange(new Object[] { new FbParameter("@start", start), new FbParameter("@stop", stop), new FbParameter("@signIn", (Int32)LogEventType.SignIn), new FbParameter("@signInFailure", (Int32)LogEventType.SignInFailure), new FbParameter("@signOut", (Int32)LogEventType.SignOut)}); Trace.WriteLine(adapter.SelectCommand.CommandText); foreach (FbParameter p in adapter.SelectCommand.Parameters) { Trace.WriteLine(p.Value.ToString()); } adapter.Fill(entries); } } return entries; }

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  • Reading lines of data from text files using java

    - by razshan
    I have a text file with x amount of lines. each line holds a integer number. When the user clicks a button, an action is performed via actionlistener where it should list all the values as displayed on the text file. However, right now I have linenum set to 10 implying I already told the code that just work with 10 lines of the text file. So, if my text file has only 3 rows/lines of data...it will list those lines and for rest of the other 7 lines, it will spit out "null". I recall there is a way to use ellipsis to let the program know that you don't know the exact value but at the end it calculates it based on the given information. Where my given information will the number of lines with numbers(data). Below is part of the code. private class thehandler implements ActionListener{ public void actionPerformed(ActionEvent event){ BufferedReader inputFile=null; try { FileReader freader =new FileReader("Data.txt"); inputFile = new BufferedReader(freader); String MAP = ""; int linenum=10; while(linenum > 0) { linenum=linenum-1; MAP = inputFile.readLine();//read the next line until the specfic line is found System.out.println(MAP); } } catch( Exception y ) { y.printStackTrace(); } }}

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  • Apply [ThreadStatic] attribute to a method in external assembly

    - by Sen Jacob
    Can I use an external assembly's static method like [ThreadStatic] method? Here is my situation. The assembly class (which I do not have access to its source) has this structure public class RegistrationManager() { private RegistrationManager() {} public static void RegisterConfiguration(int ID) {} public static object DoWork() {} public static void UnregisterConfiguration(int ID) {} } Once registered, I cannot call the DoWork() with a different ID without unregistering the previously registered one. Actually I want to call the DoWork() method with different IDs simultaneously with multi-threading. If the RegisterConfiguration(int ID) method was [ThreadStatic], I could have call it in different threads without problems with calls, right? So, can I apply the [ThreadStatic] attribute to this method or is there any other way I can call the two static methods same time without waiting for other thread to unregister it? If I check it like the following, it should work. for(int i=0; i < 10; i++) { new Thread(new ThreadStart(() => Checker(i))).Start(); } public string Checker(int i) { public static void RegisterConfiguration(i); // Now i cannot register second time public static object DoWork(i); Thread.Sleep(5000); // DoWork() may take a little while to complete before unregistered public static void UnregisterConfiguration(i); }

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  • C++ Virtual Methods for Class-Specific Attributes or External Structure

    - by acanaday
    I have a set of classes which are all derived from a common base class. I want to use these classes polymorphically. The interface defines a set of getter methods whose return values are constant across a given derived class, but vary from one derived class to another. e.g.: enum AVal { A_VAL_ONE, A_VAL_TWO, A_VAL_THREE }; enum BVal { B_VAL_ONE, B_VAL_TWO, B_VAL_THREE }; class Base { //... virtual AVal getAVal() const = 0; virtual BVal getBVal() const = 0; //... }; class One : public Base { //... AVal getAVal() const { return A_VAL_ONE }; BVal getBVal() const { return B_VAL_ONE }; //... }; class Two : public Base { //... AVal getAVal() const { return A_VAL_TWO }; BVal getBVal() const { return B_VAL_TWO }; //... }; etc. Is this a common way of doing things? If performance is an important consideration, would I be better off pulling the attributes out into an external structure, e.g.: struct Vals { AVal a_val; VBal b_val; }; storing a Vals* in each instance, and rewriting Base as follows? class Base { //... public: AVal getAVal() const { return _vals->a_val; }; BVal getBVal() const { return _vals->b_val; }; //... private: Vals* _vals; }; Is the extra dereference essentially the same as the vtable lookup? What is the established idiom for this type of situation? Are both of these solutions dumb? Any insights are greatly appreciated

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  • In AS3/Flex, how can I get from flat data to hierarchical data?

    - by Dave S
    I have some data that gets pulled out of a database and mapped to an arraycollection. This data has a field called parentid, and I would like to map the data into a new arraycollection with hierarchical information to then feed to an advanced data grid. I think I'm basically trying to take the parent object, add a new property/field/variable of type ArrayCollection called children and then remove the child object from the original list and clone it into the children array? Any help would be greatly appreciated, and I apologize ahead of time for this code: private function PutChildrenWithParents(accountData : ArrayCollection) : ArrayCollection{ var pos_inner:int = 0; var pos_outer:int = 0; while(pos_outer < accountData.length){ if (accountData[pos_outer].ParentId != null){ pos_inner = 0; while(pos_inner < accountData.length){ if (accountData[pos_inner].Id == accountData[pos_outer].ParentId){ accountData.addItemAt( accountData[pos_inner] + {children:new ArrayCollection(accountData[pos_outer])}, pos_inner ); accountData.removeItemAt(pos_outer); accountData.removeItemAt(pos_inner+1); } pos_inner++; } } pos_outer++; } return accountData; }

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