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• can a python script know that another instance of the same script is running... and then talk to it?

  - by Justin Grant

  I'd like to prevent multiple instances of the same long-running python command-line script from running at the same time, and I'd like the new instance to be able to send data to the original insance before the new instance commits suicide. How can I do this in a cross-platform way? Specifically, I'd like to enable the following behavior: "foo.py" is launched from the command line, and it will stay running for a long time-- days or weeks until the machine is rebooted or the parent process kills it. every few minutes the same script is launched again, but with different command-line parameters when launched, the script should see if any other instances are running. if other instances are running, then instance #2 should send its command-line parameters to instance #1, and then instance #2 should exit. instance #1, if it receives command-line parameters from another script, should spin up a new thread and (using the command-line parameters sent in the step above) start performing the work that instance #2 was going to perform. So I'm looking for two things: how can a python program know another instance of itself is running, and then how can one python command-line program communicate with another? Making this more complicated, the same script needs to run on both Windows and Linux, so ideally the solution would use only the Python standard library and not any OS-specific calls. Although if I need to have a Windows codepath and an *nix codepath (and a big if statement in my code to choose one or the other), that's OK if a "same code" solution isn't possible. I realize I could probably work out a file-based approach (e.g. instance #1 watches a directory for changes and each instance drops a file into that directory when it wants to do work) but I'm a little concerned about cleaning up those files after a non-graceful machine shutdown. I'd ideally be able to use an in-memory solution. But again I'm flexible, if a persistent-file-based approach is the only way to do it, I'm open to that option. More details: I'm trying to do this because our servers are using a monitoring tool which supports running python scripts to collect monitoring data (e.g. results of a database query or web service call) which the monitoring tool then indexes for later use. Some of these scripts are very expensive to start up but cheap to run after startup (e.g. making a DB connection vs. running a query). So we've chosen to keep them running in an infinite loop until the parent process kills them. This works great, but on larger servers 100 instances of the same script may be running, even if they're only gathering data every 20 minutes each. This wreaks havoc with RAM, DB connection limits, etc. We want to switch from 100 processes with 1 thread to one process with 100 threads, each executing the work that, previously, one script was doing. But changing how the scripts are invoked by the monitoring tool is not possible. We need to keep invocation the same (launch a process with different command-line parameters) but but change the scripts to recognize that another one is active, and have the "new" script send its work instructions (from the command line params) over to the "old" script.

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• Undefined reference to vtable

  - by RyanG

  So, I'm getting the infamously horrible "undefined reference to 'vtable..." error for the following code (The class in question is CGameModule.) and I cannot for the life of me understand what the problem is. At first, I thought it was related to forgetting to give a virtual function a body, but as far as I understand, everything is all here. The inheritance chain is a little long, but here is the related source code. I'm not sure what other information I should provide. My code: class CGameModule : public CDasherModule { public: CGameModule(Dasher::CEventHandler *pEventHandler, CSettingsStore *pSettingsStore, CDasherInterfaceBase *pInterface, ModuleID_t iID, const char *szName) : CDasherModule(pEventHandler, pSettingsStore, iID, 0, szName) { g_pLogger->Log("Inside game module constructor"); m_pInterface = pInterface; } virtual ~CGameModule() {}; std::string GetTypedTarget(); std::string GetUntypedTarget(); bool DecorateView(CDasherView *pView) { //g_pLogger->Log("Decorating the view"); return false; } void SetDasherModel(CDasherModel *pModel) { m_pModel = pModel; } virtual void HandleEvent(Dasher::CEvent *pEvent); private: CDasherNode *pLastTypedNode; CDasherNode *pNextTargetNode; std::string m_sTargetString; size_t m_stCurrentStringPos; CDasherModel *m_pModel; CDasherInterfaceBase *m_pInterface; }; } Inherits from... class CDasherModule; typedef std::vector<CDasherModule*>::size_type ModuleID_t; /// \ingroup Core /// @{ class CDasherModule : public Dasher::CDasherComponent { public: CDasherModule(Dasher::CEventHandler * pEventHandler, CSettingsStore * pSettingsStore, ModuleID_t iID, int iType, const char *szName); virtual ModuleID_t GetID(); virtual void SetID(ModuleID_t); virtual int GetType(); virtual const char *GetName(); virtual bool GetSettings(SModuleSettings **pSettings, int *iCount) { return false; }; private: ModuleID_t m_iID; int m_iType; const char *m_szName; }; Which inherits from.... namespace Dasher { class CEvent; class CEventHandler; class CDasherComponent; }; /// \ingroup Core /// @{ class Dasher::CDasherComponent { public: CDasherComponent(Dasher::CEventHandler* pEventHandler, CSettingsStore* pSettingsStore); virtual ~CDasherComponent(); void InsertEvent(Dasher::CEvent * pEvent); virtual void HandleEvent(Dasher::CEvent * pEvent) {}; bool GetBoolParameter(int iParameter) const; void SetBoolParameter(int iParameter, bool bValue) const; long GetLongParameter(int iParameter) const; void SetLongParameter(int iParameter, long lValue) const; std::string GetStringParameter(int iParameter) const; void SetStringParameter(int iParameter, const std::string & sValue) const; ParameterType GetParameterType(int iParameter) const; std::string GetParameterName(int iParameter) const; protected: Dasher::CEventHandler *m_pEventHandler; CSettingsStore *m_pSettingsStore; }; /// @} #endif

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• Need help to properly remove duplicates in NHibernate

  - by Michael D. Kirkpatrick

  Here is the problem I am having. I have a database with over 100 records in it. I am paging through the data to get 9 results at a time. When I added a check to see if items are active, it caused the results to start doubling up. A little background: "Product" is the actual product line "ProductSkus" are the actual products that exist in the product line When there is more then 1 ProductSku within Product, it causes a duplicate entry to be returned. See the NHibernate Query below: result = this.Session.CreateCriteria<Model.Product>() .Add(Expression.Eq("IsActive", true)) .AddOrder(new Order("Name", true)) .SetFirstResult(indexNumber).SetMaxResults(maxNumber) // This part of the query duplicates the products .CreateAlias("ProductSkus", "ProdSkus", JoinType.InnerJoin) .Add(Expression.Eq("ProdSkus.IsActive", true)) .CreateAlias("ProductToSubcategory", "ProdToSubcat") .CreateAlias("ProdToSubcat.ProductSubcategory", "ProdSubcat") .Add(Expression.Eq("ProdSubcat.ID", subCatId)) // This part takes out the duplicate products - Removes too many items... // Turns out that with .SetFirstResult(indexNumber).SetMaxResults(maxNumber) // it gets 9 records back then the duplicates are removed. // Example: // Total Records over 100 // Max = 9 // 4 Duplicates removed // Yields 5 records when there should be 9 // Why??? This line is ran in NHibernate on the data after it has been extracted from the SQL server. .SetResultTransformer(new NHibernate.Transform.DistinctRootEntityResultTransformer()) .List<Model.Product>(); I added the DistinctRootEntityResultTransformer to clean up the duplicates. The problem is that it pulls 9 records back that contains duplicates. DistinctRootEntityResultTransformer then cleans up the duplicates in the 9 records. I am basically needing a distinct statement to be ran on the SQL server to begin with. However, distinct on SQL is not going to work since NHibernate by default wants to add every field from every table in the select part of the statement. I am only using the fields that belong to the root table to begin with (Model.Product). If I can tell NHibernate to not add the fields to the joined tables into the select part of the statement along with adding Distinct, it would work. I use NHibernare Profiler to see the actual query: SELECT top 9 this_.ID as ID351_3_, this_.Name as Name351_3_, this_.Description as Descript3_351_3_, this_.IsActive as IsActive351_3_, this_.ManufacturerID as Manufact5_351_3_, prodskus1_.ID as ID373_0_, prodskus1_.Description as Descript2_373_0_, prodskus1_.PartNumber as PartNumber373_0_, prodskus1_.Price as Price373_0_, prodskus1_.IsKit as IsKit373_0_, prodskus1_.IsActive as IsActive373_0_, prodskus1_.IsFeaturedProduct as IsFeatur7_373_0_, prodskus1_.DateAdded as DateAdded373_0_, prodskus1_.Weight as Weight373_0_, prodskus1_.TimesViewed as TimesVi10_373_0_, prodskus1_.TimesOrdered as TimesOr11_373_0_, prodskus1_.ProductID as ProductID373_0_, prodskus1_.OverSizedBoxID as OverSiz13_373_0_, prodtosubc2_.ID as ID362_1_, prodtosubc2_.MasterSubcategory as MasterSu2_362_1_, prodtosubc2_.ProductID as ProductID362_1_, prodtosubc2_.ProductSubcategoryID as ProductS4_362_1_, prodsubcat3_.ID as ID352_2_, prodsubcat3_.Name as Name352_2_, prodsubcat3_.ProductCategoryID as ProductC3_352_2_, prodsubcat3_.ImageID as ImageID352_2_, prodsubcat3_.TriggerShow as TriggerS5_352_2_ FROM Product this_ inner join ProductSku prodskus1_ on this_.ID = prodskus1_.ProductID and (prodskus1_.IsActive = 1) inner join ProductToSubcategory prodtosubc2_ on this_.ID = prodtosubc2_.ProductID inner join ProductSubcategory prodsubcat3_ on prodtosubc2_.ProductSubcategoryID = prodsubcat3_.ID WHERE this_.IsActive = 1 /* @p0 */ and prodskus1_.IsActive = 1 /* @p1 */ and prodsubcat3_.ID = 3 /* @p2 */ ORDER BY this_.Name asc If I hand modify the query and run it directly on the SQL server I get the result set I want (I removed all the extra fields in the select section and added DISTINCT): SELECT DISTINCT top 9 this_.ID as ID351_3_, this_.Name as Name351_3_, this_.Description as Descript3_351_3_, this_.IsActive as IsActive351_3_, this_.ManufacturerID as Manufact5_351_3_, FROM Product this_ inner join ProductSku prodskus1_ on this_.ID = prodskus1_.ProductID and (prodskus1_.IsActive = 1) inner join ProductToSubcategory prodtosubc2_ on this_.ID = prodtosubc2_.ProductID inner join ProductSubcategory prodsubcat3_ on prodtosubc2_.ProductSubcategoryID = prodsubcat3_.ID WHERE this_.IsActive = 1 /* @p0 */ and prodskus1_.IsActive = 1 /* @p1 */ and prodsubcat3_.ID = 3 /* @p2 */ ORDER BY this_.Name asc The big question I now must ask is... What must I change in the NHibernate Query to ultimately get the exact same result? Thanks in advance.

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• Converting PHP pagination to jQuery?

  - by ClarkSKent

  Hey, I have been trying to get this pagination class that I am using to be more ajaxy - meaning when I click on the page number like page [2] the data loads, but I want to load in the data without going to a different page (HTTP request in the background, with no page reloads). Being new to both php and jquery, I am a little unsure on how to achieve this result, especially while using a php class. This is what the main page looks like by the way: <?php $categoryId=$_GET['category']; echo $categoryId; ?> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.1/jquery.min.js"></script> <script type="text/javascript" src="jquery_page.js"></script> <?php //Include the PS_Pagination class include('ps_pagination.php'); //Connect to mysql db $conn = mysql_connect('localhost', 'root', 'root'); mysql_select_db('ajax_demo',$conn); $sql = "select * from explore where category='$categoryId'"; //Create a PS_Pagination object $pager = new PS_Pagination($conn, $sql, 3, 11, 'param1=value1&param2=value2'); //The paginate() function returns a mysql //result set for the current page $rs = $pager->paginate(); //Loop through the result set echo "<table width='800px'>"; while($row = mysql_fetch_assoc($rs)) { echo "<tr>"; echo"<td>"; echo $row['id']; echo"</td>"; echo"<td>"; echo $row['site_description']; echo"</td>"; echo"<td>"; echo $row['site_price']; echo"</td>"; echo "</tr>"; } echo "</table>"; echo "<ul id='pagination'>"; echo "<li>"; //Display the navigation echo $pager->renderFullNav(); echo "</li>"; echo "</ul>"; ?> <div id="loading" ></div> <div id="content" ></div> Would I need to do something with this part of the class?, as seen above: $pager = new PS_Pagination($conn, $sql, 3, 11, 'param1=value1&param2=value2'); Or this?: echo $pager->renderFullNav(); I don't no much about jquery,but i guess I would start it like: $("#pagination li").click(function() { Then load something maybe... I don't no. Any help on this would be great. Thanks.

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• WP7 listbox binding not working properly

  - by Marco

  A noob error for sure (I started yesterday afternoon developing in WP7), but I'm wasting a lot time on it. I post my class and a little part of my code: public class ChronoLaps : INotifyPropertyChanged { private ObservableCollection<ChronoLap> laps = null; public int CurrentLap { get { return lap; } set { if (value == lap) return; // Some code here .... ChronoLap newlap = new ChronoLap() { // Some code here ... }; Laps.Insert(0, newlap); lap = value; NotifyPropertyChanged("CurrentLap"); NotifyPropertyChanged("Laps"); } } public ObservableCollection<ChronoLap> Laps { get { return laps; } set { if (value == laps) return; laps = value; if (laps != null) { laps.CollectionChanged += delegate { MeanTime = Laps.Sum(p => p.Time.TotalMilliseconds) / (Laps.Count * 1000); NotifyPropertyChanged("MeanTime"); }; } NotifyPropertyChanged("Laps"); } } } MainPage.xaml.cs public partial class MainPage : PhoneApplicationPage { public ChronoLaps History { get; private set; } private void butStart_Click(object sender, EventArgs e) { History = new ChronoLaps(); // History.Laps.Add(new ChronoLap() { Distance = 0 }); LayoutRoot.DataContext = History; } } MainPage.xaml <phone:PhoneApplicationPage> <Grid x:Name="LayoutRoot" Background="Transparent"> <Grid Grid.Row="2"> <ScrollViewer Margin="-5,13,3,36" Height="758"> <ListBox Name="lbHistory" ItemContainerStyle="{StaticResource ListBoxStyle}" ItemsSource="{Binding Laps}" HorizontalAlignment="Left" Margin="5,25,0,0" VerticalAlignment="Top" Width="444"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <TextBlock Text="{Binding Lap}" Width="40" /> <TextBlock Text="{Binding Time}" Width="140" /> <TextBlock Text="{Binding TotalTime}" Width="140" /> <TextBlock Text="{Binding Distance}" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </ScrollViewer> </Grid> </Grid> </phone:PhoneApplicationPage> Problem is that when I add one or more items to History.Laps collection, my listbox is not refreshed and these items don't appear. But if I remove comment on // History.Laps.Add(new ChronoLap()... line, this item appear and so every other inserted later. More: if I remove that comment and then write History.Laps.Clear() (before or after setting binding) binding is not working anymore. It's like it gets crazy if collection is empty. I really don't understand the reason... UPDATE AND SOLUTION: If i move History = new ChronoLaps(); LayoutRoot.DataContext = History; from butStart_Click to public MainPage() everything works as expected. Can someone explain me the reason?

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• Reordering Variadic Parameters

  - by void-pointer

  I have come across the need to reorder a variadic list of parameters that is supplied to the constructor of a struct. After being reordered based on their types, the parameters will be stored as a tuple. My question is how this can be done so that a modern C++ compiler (e.g. g++-4.7) will not generate unnecessary load or store instructions. That is, when the constructor is invoked with a list of parameters of variable size, it efficiently pushes each parameter into place based on an ordering over the parameters' types. Here is a concrete example. Assume that the base type of every parameter (without references, rvalue references, pointers, or qualifiers) is either char, int, or float. How can I make it so that all the parameters of base type char appear first, followed by all of those of base type int (which leaves the parameters of base type float last). The relative order in which the parameters were given should not be violated within sublists of homogeneous base type. Example: foo::foo() is called with arguments float a, char&& b, const float& c, int&& d, char e. The tuple tupe is std::tuple<char, char, int, float, float>, and it is constructed like so: tuple_type{std::move(b), e, std::move(d), a, c}. Consider the struct defined below, and assume that the metafunction deduce_reordered_tuple_type is already implemented. How would you write the constructor so that it works as intended? If you think that the code for deduce_reodered_tuple_type, would be useful to you, I can provide it; it's a little long. template <class... Args> struct foo { // Assume that the metafunction deduce_reordered_tuple_type is defined. typedef typename deduce_reordered_tuple_type<Args...>::type tuple_type; tuple_type t_; foo(Args&&... args) : t_{reorder_and_forward_parameters<Args>(args)...} {} }; Edit 1 The technique I describe above does have applications in mathematical frameworks that make heavy use of expression templates, variadic templates, and metaprogramming in order to perform aggressive inlining. Suppose that you wish to define an operator that takes the product of several expressions, each of which may be passed by reference, reference to const, or rvalue reference. (In my case, the expressions are conditional probability tables and the operation is the factor product, but something like matrix multiplication works suitably as well.) You need access to the data provided by each expression in order to evaluate the product. Consequently, you must move the expressions passed as rvalue references, copy the expressions passed by reference to const, and take the addresses of expressions passed by reference. Using the technique I describe above now poses several benefits. Other expressions can use uniform syntax to access data elements from this expression, since all of the heavy-lifting metaprogramming work is done beforehand, within the class. We can save stack space by grouping the pointers together and storing the larger expressions towards the end of the tuple. Implementing certain types of queries becomes much easier (e.g. check whether any of the pointers stored in the tuple aliases a given pointer). Thank you very much for your help!

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• won't repaint a different Month after pressing button in my calendar

  - by DarkStar123

  I'm trying to build a Calendar in Java as a little project I thought of, But I can't seem to change the name of the Month every time I click the Next button. here's my code! package drawing; import javax.swing.*; import java.awt.*; import java.awt.event.*; public class Drawing_something extends JPanel{ int[] calender_squares = {1, 2, 3, 4, 5, 6, 7}; String[] Month = {"January", "February", "March", "April","May","June","July", "August","September","October","November","December"}; int i = 0; Graphics c; @Override public void paintComponent(Graphics c){ super.paintComponent(c); this.setBackground(Color.WHITE); int WIDTH = 55, HEIGHT = 65; for (int in: calender_squares) { for (int counter = 0; counter < 7; counter++){ c.drawRect(50, 50, 100, 100); c.drawRect(50, 50, 700, 500); c.copyArea(50, 50, 600, 500, 100, 0); c.copyArea(50, 50, 600, 400, 0, 100); } } for (int date = 1; date <= 30; date++) { String s = String.valueOf(date); c.drawString(s, WIDTH, HEIGHT); if (date <= 6){ WIDTH += 100; } else if (date == 7){ WIDTH = 55; HEIGHT = 165; }else if (date <= 13){ WIDTH += 100; }else if (date == 14){ WIDTH = 55; HEIGHT = 265; }else if (date <= 20){ WIDTH += 100; }else if (date == 21){ WIDTH = 55; HEIGHT = 365; }else if (date <= 27){ WIDTH += 100; }else if (date == 28){ WIDTH = 55; HEIGHT = 465; }else if (date <= 30){ WIDTH += 100; } } c.setFont(new Font("default", Font.BOLD, 40)); c.drawString(Month[i], 320, 45); } public Drawing_something(){ setLayout(new BorderLayout()); JButton N = new JButton("NEXT"); JButton B = new JButton("BACK"); JPanel P = new JPanel(); P.add(B); P.add(N); add(P, BorderLayout.SOUTH); B.addActionListener(new HandlerClass()); N.addActionListener(new NextClass()); } public class HandlerClass implements ActionListener{ public void actionPerformed(ActionEvent e){ } } public class NextClass implements ActionListener{ public void actionPerformed(ActionEvent e){ if (i == 11){ i = 0; } i = i + 1; c.drawString(Month[i], 320, 45); } } public static void main(String[] args){ JFrame mainFrame = new JFrame("Calender"); mainFrame.add(new Drawing_something()); mainFrame.setSize(850, 650); mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); mainFrame.setVisible(true); } } if anyone could help that would be much appreciated!! Thanks in advance!!

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• QuickBox2D poly behaviour vs box or circle

  - by Ben Kanizay

  Hi I've played a little with Box2D before and have just started using QuickBox2D which makes things heaps easier. I am however getting different behaviour with a specific poly shape than I am with a box. All other properties are the same. I've included 3 simple examples and their source below. What I really want to work is Example 1 with both objects as poly. As you can see, it seems like the 'paddle' poly is the one that's failing - the 'ball' (whether it's a poly or circle) just falls straight through it instead of bouncing off as it does with a box 'paddle' object. Would appreciate some help or insight. As I can only post one line at this stage, the swf previews of the 3 examples can be seen here Example 1 source: package { import com.actionsnippet.qbox.QuickBox2D; import com.actionsnippet.qbox.QuickObject; import flash.display.MovieClip; public class Eg1 extends MovieClip { private var sim:QuickBox2D; private var paddle:QuickObject; private var ball:QuickObject; public function Eg1() { this.sim = new QuickBox2D(this); this.paddle = this.sim.addPoly({ x:13, y:19, angle:0, density:0, draggable:false, isBullet:true, verts:[[-3.84,-0.67,-2.84,-1,-2.17,-0.33,2.17,-0.33,2.84,-1,3.84,-0.67,2.84,1,-2.51,1]] }); this.ball = this.sim.addPoly({ x:13, y:1, restitution:1, friction:1, draggable:false, isBullet:true, verts:[[-0.34,-1,0.34,-1,0.67,-0.33,0.67,0.33,0.34,1,-0.34,1,-0.67,0.33,-0.67,-0.33]] }); this.sim.start(); } }} Example 2 source: package { import com.actionsnippet.qbox.QuickBox2D; import com.actionsnippet.qbox.QuickObject; import flash.display.MovieClip; public class Eg2 extends MovieClip { private var sim:QuickBox2D; private var paddle:QuickObject; private var ball:QuickObject; public function Eg2() { this.sim = new QuickBox2D(this); this.paddle = this.sim.addBox({ x:13, y:19, angle:0, density:0, draggable:false, isBullet:true, width:8 }); this.ball = this.sim.addPoly({ x:13, y:1, restitution:1, friction:1, draggable:false, isBullet:true, verts:[[-0.34,-1,0.34,-1,0.67,-0.33,0.67,0.33,0.34,1,-0.34,1,-0.67,0.33,-0.67,-0.33]] }); this.sim.start(); } }} Example 3 source: package { import com.actionsnippet.qbox.QuickBox2D; import com.actionsnippet.qbox.QuickObject; import flash.display.MovieClip; public class Eg3 extends MovieClip { private var sim:QuickBox2D; private var paddle:QuickObject; private var ball:QuickObject; public function Eg3() { this.sim = new QuickBox2D(this); this.paddle = this.sim.addPoly({ x:13, y:19, angle:0, density:0, draggable:false, isBullet:true, verts:[[-3.84,-0.67,-2.84,-1,-2.17,-0.33,2.17,-0.33,2.84,-1,3.84,-0.67,2.84,1,-2.51,1]] }); this.ball = this.sim.addCircle({ x:13, y:1, restitution:1, friction:1, draggable:false, isBullet:true, radius:1 }); this.sim.start(); } }}

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• Dynamic obfuscation by self-modifying code

  - by Fallout2

  Hi all, Here what's i am trying to do: assume you have two fonction void f1(int *v) { *v = 55; } void f2(int *v) { *v = 44; } char *template; template = allocExecutablePages(...); char *allocExecutablePages (int pages) { template = (char *) valloc (getpagesize () * pages); if (mprotect (template, getpagesize (), PROT_READ|PROT_EXEC|PROT_WRITE) == -1) { perror (“mprotect”); } } I would like to do a comparison between f1 and f2 (so tell what is identical and what is not) (so get the assembly lines of those function and make a line by line comparison) And then put those line in my template. Is there a way in C to do that? THanks Update Thank's for all you answers guys but maybe i haven't explained my need correctly. basically I'm trying to write a little obfuscation method. The idea consists in letting two or more functions share the same location in memory. A region of memory (which we will call a template) is set up containing some of the machine code bytes from the functions, more specifically, the ones they all have in common. Before a particular function is executed, an edit script is used to patch the template with the necessary machine code bytes to create a complete version of that function. When another function assigned to the same template is about to be executed, the process repeats, this time with a different edit script. To illustrate this, suppose you want to obfuscate a program that contains two functions f1 and f2. The first one (f1) has the following machine code bytes Address Machine code 0 10 1 5 2 6 3 20 and the second one (f2) has Address Machine code 0 10 1 9 2 3 3 20 At obfuscation time, one will replace f1 and f2 by the template Address Machine code 0 10 1 ? 2 ? 3 20 and by the two edit scripts e1 = {1 becomes 5, 2 becomes 6} and e2 = {1 becomes 9, 2 becomes 3}. #include <stdlib.h> #include <string.h> typedef unsigned int uint32; typedef char * addr_t; typedef struct { uint32 offset; char value; } EDIT; EDIT script1[200], script2[200]; char *template; int template_len, script_len = 0; typedef void(*FUN)(int *); int val, state = 0; void f1_stub () { if (state != 1) { patch (script1, script_len, template); state = 1; } ((FUN)template)(&val); } void f2_stub () { if (state != 2) { patch (script2, script_len, template); state = 2; } ((FUN)template)(&val); } int new_main (int argc, char **argv) { f1_stub (); f2_stub (); return 0; } void f1 (int *v) { *v = 99; } void f2 (int *v) { *v = 42; } int main (int argc, char **argv) { int f1SIZE, f2SIZE; /* makeCodeWritable (...); */ /* template = allocExecutablePages(...); */ /* Computed at obfuscation time */ diff ((addr_t)f1, f1SIZE, (addr_t)f2, f2SIZE, script1, script2, &script_len, template, &template_len); /* We hide the proper code */ memset (f1, 0, f1SIZE); memset (f2, 0, f2SIZE); return new_main (argc, argv); } So i need now to write the diff function. that will take the addresses of my two function and that will generate a template with the associated script. So that is why i would like to compare bytes by bytes my two function Sorry for my first post who was not very understandable! Thank you

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• I try to change activity to next page, but it can't.

  - by Daisy

  I try to change page on android application. It have error but look like its swap a little while. public class gps_gui extends Activity implements View.OnClickListener{ /** Called when the activity is first created. */ private static final int ACTIVITY_CREATE = 0; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); final Button login = (Button) findViewById(R.id.login); login.setOnClickListener((OnClickListener) this); } public void onClick(View v){ //Toast.makeText(this, "Already Login",Toast.LENGTH_SHORT).show(); Intent i = new Intent(this, SecondPage.class); startActivityForResult(i, ACTIVITY_CREATE); } } public class SecondPage extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.second_page); } } In AndriodManifest.xml <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="gps.GUI" android:versionCode="1" android:versionName="1.0"> <application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".gps_gui" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name="second_page"></activity> </application> <uses-sdk android:minSdkVersion="8" /> </manifest> Anyone can help me ? thanks Errors: 01-29 13:56:57.709: ERROR/AndroidRuntime(393): FATAL EXCEPTION: main 01-29 13:56:57.709: ERROR/AndroidRuntime(393): android.content.ActivityNotFoundException: Unable to find explicit activity class {gps.GUI/gps.GUI.SecondPage}; have you declared this activity in your AndroidManifest.xml? 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1404) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.app.Instrumentation.execStartActivity(Instrumentation.java:1378) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.app.Activity.startActivityForResult(Activity.java:2817) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at gps.GUI.gps_gui$1.onClick(gps_gui.java:30) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.view.View.performClick(View.java:2408) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.view.View$PerformClick.run(View.java:8816) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.os.Handler.handleCallback(Handler.java:587) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.os.Handler.dispatchMessage(Handler.java:92) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.os.Looper.loop(Looper.java:123) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at android.app.ActivityThread.main(ActivityThread.java:4627) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at java.lang.reflect.Method.invokeNative(Native Method) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at java.lang.reflect.Method.invoke(Method.java:521) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 01-29 13:56:57.709: ERROR/AndroidRuntime(393): at dalvik.system.NativeStart.main(Native Method)

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• jquery drag and drop script and problem in reading json array

  - by Mac Taylor

  i made a script , exactly like wordpress widgets page and u can drag and drop objects this is my jquery script : <script type="text/javascript" >$(function(){ $('.widget') .each(function(){ $(this).hover(function(){ $(this).find('h4').addClass('collapse'); }, function(){ $(this).find('h4').removeClass('collapse'); }) .find('h4').hover(function(){ $(this).find('.in-widget-title').css('visibility', 'visible'); }, function(){ $(this).find('.in-widget-title').css('visibility', 'hidden'); }) .click(function(){ $(this).siblings('.widget-inside').toggle(); //Save state on change of collapse state of panel updateWidgetData(); }) .end() .find('.in-widget-title').css('visibility', 'hidden'); }); $('.column').sortable({ connectWith: '.column', handle: 'h4', cursor: 'move', placeholder: 'placeholder', forcePlaceholderSize: true, opacity: 0.4, start: function(event, ui){ //Firefox, Safari/Chrome fire click event after drag is complete, fix for that if($.browser.mozilla || $.browser.safari) $(ui.item).find('.widget-inside').toggle(); }, stop: function(event, ui){ ui.item.css({'top':'0','left':'0'}); //Opera fix if(!$.browser.mozilla && !$.browser.safari) updateWidgetData(); } }) .disableSelection(); }); function updateWidgetData(){ var items=[]; $('.column').each(function(){ var columnId=$(this).attr('id'); $('.widget', this).each(function(i){ var collapsed=0; if($(this).find('.widget-inside').css('display')=="none") collapsed=1; //Create Item object for current panel var item={ id: $(this).attr('id'), collapsed: collapsed, order : i, column: columnId }; //Push item object into items array items.push(item); }); }); //Assign items array to sortorder JSON variable var sortorder={ items: items }; //Pass sortorder variable to server using ajax to save state $.post("blocks.php"+"&order="+$.toJSON(sortorder), function(data){ $('#console').html(data).fadeIn("slow"); }); } </script> main part is saving object orders in table and this is my php part : function stripslashes_deep($value) { $value = is_array($value) ? array_map('stripslashes_deep', $value) : stripslashes($value); return $value; } $order = $_GET['order']; $order = sql_quote($order); if(empty($order)){ echo "Invalid data"; exit; } global $db,$prefix; if (get_magic_quotes_gpc()) { $_POST = array_map('stripslashes_deep', $_POST); $_GET = array_map('stripslashes_deep', $_GET); $_COOKIE = array_map('stripslashes_deep', $_COOKIE); $_REQUEST = array_map('stripslashes_deep', $_REQUEST); } $data=json_decode($order); foreach($newdata->items as $item) { //Extract column number for panel $col_id=preg_replace('/[^\d\s]/', '', $item->column); //Extract id of the panel $widget_id=preg_replace('/[^\d\s]/', '', $item->id); $sql="UPDATE blocks_tbl SET bposition='$col_id', weight='".$item->order."' WHERE id='".$widget_id."'"; mysql_query($sql) or die('Error updating widget DB'); } print_r($order); now forexample the output is this : items\":[{\"id\":\"item26\",\"collapsed\":1,\"order\":0,\"column\":\"c\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":0,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":1,\"column\":\"i\"},{\"id\":\"item1\",\"collapsed\":1,\"order\":2,\"column\":\"i\"},{\"id\":\"item3\",\"collapsed\":1,\"order\":3,\"column\":\"i\"},{\"id\":\"item16\",\"collapsed\":1,\"order\":4,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":5,\"column\":\"i\"},{\"id\":\"item6\",\"collapsed\":1,\"order\":6,\"column\":\"i\"},{\"id\":\"item17\",\"collapsed\":1,\"order\":7,\"column\":\"i\"},{\"id\":\"item19\",\"collapsed\":1,\"order\":8,\"column\":\"i\"},{\"id\":\"item10\",\"collapsed\":1,\"order\":9,\"column\":\"i\"},{\"id\":\"item11\",\"collapsed\":1,\"order\":10,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":0,\"column\":\"l\"},{\"id\":\"item5\",\"collapsed\":1,\"order\":1,\"column\":\"l\"},{\"id\":\"item8\",\"collapsed\":1,\"order\":2,\"column\":\"l\"},{\"id\":\"item13\",\"collapsed\":1,\"order\":3,\"column\":\"l\"},{\"id\":\"item21\",\"collapsed\":1,\"order\":4,\"column\":\"l\"},{\"id\":\"item28\",\"collapsed\":1,\"order\":5,\"column\":\"l\"},{\"id\":\"item7\",\"collapsed\":1,\"order\":0,\"column\":\"r\"},{\"id\":\"item20\",\"collapsed\":1,\"order\":1,\"column\":\"r\"},{\"id\":\"item15\",\"collapsed\":1,\"order\":2,\"column\":\"r\"},{\"id\":\"item18\",\"collapsed\":1,\"order\":3,\"column\":\"r\"},{\"id\":\"item14\",\"collapsed\":1,\"order\":4,\"column\":\"r\"}]} question is how can i find out column_id or order im a little bit confused

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• How do I recursively define a Hash in Ruby from supplied arguments?

  - by Sarah Beckham

  This snippet of code populates an @options hash. values is an Array which contains zero or more heterogeneous items. If you invoke populate with arguments that are Hash entries, it uses the value you specify for each entry to assume a default value. def populate(*args) args.each do |a| values = nil if (a.kind_of? Hash) # Converts {:k => "v"} to `a = :k, values = "v"` a, values = a.to_a.first end @options[:"#{a}"] ||= values ||= {} end end What I'd like to do is change populate such that it recursively populates @options. There is a special case: if the values it's about to populate a key with are an Array consisting entirely of (1) Symbols or (2) Hashes whose keys are Symbols (or some combination of the two), then they should be treated as subkeys rather than the values associated with that key, and the same logic used to evaluate the original populate arguments should be recursively re-applied. That was a little hard to put into words, so I've written some test cases. Here are some test cases and the expected value of @options afterwards: populate :a => @options is {:a => {}} populate :a => 42 => @options is {:a => 42} populate :a, :b, :c => @options is {:a => {}, :b => {}, :c => {}} populate :a, :b => "apples", :c => @options is {:a => {}, :b => "apples", :c => {}} populate :a => :b => @options is {:a => :b} # Because [:b] is an Array consisting entirely of Symbols or # Hashes whose keys are Symbols, we assume that :b is a subkey # of @options[:a], rather than the value for @options[:a]. populate :a => [:b] => @options is {:a => {:b => {}}} populate :a => [:b, :c => :d] => @options is {:a => {:b => {}, :c => :d}} populate :a => [:a, :b, :c] => @options is {:a => {:a => {}, :b => {}, :c => {}}} populate :a => [:a, :b, "c"] => @options is {:a => [:a, :b, "c"]} populate :a => [:one], :b => [:two, :three => "four"] => @options is {:a => :one, :b => {:two => {}, :three => "four"}} populate :a => [:one], :b => [:two => {:four => :five}, :three => "four"] => @options is {:a => :one, :b => { :two => { :four => :five } }, :three => "four" } } It is acceptable if the signature of populate needs to change to accommodate some kind of recursive version. There is no limit to the amount of nesting that could theoretically happen. Any thoughts on how I might pull this off?

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• Flash Mouse.hide() cmd+tab(alt+tab) bring the mouse back

  - by DickieBoy

  Having a bit of trouble with Mouse.show() and losing focus of the swf This isn't my demo: but its showing the same bug http://www.foundation-flash.com/tutorials/as3customcursors/ What i do to recreate it is: mouse over the swf, hit cmd+tab to highlight another window, result is that the mouse is not brought back and is still invisible, (to get it back go to the window bar at the top of the screen and click something). I have an area in which movement is detected and an image Things I have tried package { import flash.display.Sprite; import flash.display.MovieClip; import com.greensock.*; import flash.events.*; import flash.utils.Timer; import flash.events.TimerEvent; import flash.utils.*; import flash.ui.Mouse; public class mousey_movey extends MovieClip { public var middle_of_the_flash; //pixels per second public var speeds = [0,1,3,5,10]; public var speed; public var percentage_the_mouse_is_across_the_screen; public var mouse_over_scrollable_area:Boolean; public var image_move_interval; public function mousey_movey() { middle_of_the_flash = stage.stageWidth/2; hot_area_for_movement.addEventListener(MouseEvent.MOUSE_OVER, mouseEnter); hot_area_for_movement.addEventListener(MouseEvent.MOUSE_OUT, mouseLeave); hot_area_for_movement.addEventListener(MouseEvent.MOUSE_MOVE, mouseMove); stage.addEventListener(Event.MOUSE_LEAVE, show_mouse); stage.addEventListener(MouseEvent.MOUSE_OUT, show_mouse); stage.addEventListener(Event.DEACTIVATE,show_mouse); hot_area_for_movement.alpha=0; hot_area_for_movement.x=0; hot_area_for_movement.y=34; } public function show_mouse(e) { trace(e.type) trace('show_mouse') Mouse.show(); } public function onActivate(e) { trace('activate'); Mouse.show(); } public function onDeactivate(e) { trace('deactivate'); } public function get_speed(percantage_from_middle):int { if(percantage_from_middle > 80) { return speeds[4] } else { if(percantage_from_middle > 60) { return speeds[3] } else { if(percantage_from_middle > 40) { return speeds[2] } else { if(percantage_from_middle > 20) { return speeds[1] } else { return 0; } } } } } public function mouseLeave(e:Event):void{ Mouse.show(); clearInterval(image_move_interval); } public function mouseEnter(e:Event):void{ Mouse.hide(); image_move_interval = setInterval(moveImage,1); } public function mouseMove(e:Event):void { percentage_the_mouse_is_across_the_screen = Math.round(((middle_of_the_flash-stage.mouseX)/middle_of_the_flash)*100); speed = get_speed(Math.abs(percentage_the_mouse_is_across_the_screen)); airplane_icon.x = stage.mouseX; airplane_icon.y = stage.mouseY; } public function stageMouseMove(e:Event):void{ Mouse.show(); } public function moveImage():void { if(percentage_the_mouse_is_across_the_screen > 0) { moving_image.x+=speed; airplane_icon.scaleX = -1; } else { moving_image.x-=speed; airplane_icon.scaleX = 1; } } } } Nothing too fancy, im just scrolling an image left of right at a speed which is generated by how far you are from the middle of the stage, and making an airplane moveclip follow the mouse. The events: stage.addEventListener(Event.MOUSE_LEAVE, show_mouse); stage.addEventListener(MouseEvent.MOUSE_OUT, show_mouse); stage.addEventListener(Event.DEACTIVATE,show_mouse); All fire and work correctly when in the browser, seem a little buggy when running a test through flash, was expecting this as ive experienced it before. The deactivate call even runs when testing and cmd+tabbing but shows no mouse. Any help on the matter is appreciated Thanks, Dickie

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• Binary operator overloading on a templated class (C++)

  - by GRB

  Hi all, I was recently trying to gauge my operator overloading/template abilities and as a small test, created the Container class below. While this code compiles fine and works correctly under MSVC 2008 (displays 11), both MinGW/GCC and Comeau choke on the operator+ overload. As I trust them more than MSVC, I'm trying to figure out what I'm doing wrong. Here is the code: #include <iostream> using namespace std; template <typename T> class Container { friend Container<T> operator+ <> (Container<T>& lhs, Container<T>& rhs); public: void setobj(T ob); T getobj(); private: T obj; }; template <typename T> void Container<T>::setobj(T ob) { obj = ob; } template <typename T> T Container<T>::getobj() { return obj; } template <typename T> Container<T> operator+ <> (Container<T>& lhs, Container<T>& rhs) { Container<T> temp; temp.obj = lhs.obj + rhs.obj; return temp; } int main() { Container<int> a, b; a.setobj(5); b.setobj(6); Container<int> c = a + b; cout << c.getobj() << endl; return 0; } This is the error Comeau gives: Comeau C/C++ 4.3.10.1 (Oct 6 2008 11:28:09) for ONLINE_EVALUATION_BETA2 Copyright 1988-2008 Comeau Computing. All rights reserved. MODE:strict errors C++ C++0x_extensions "ComeauTest.c", line 27: error: an explicit template argument list is not allowed on this declaration Container<T> operator+ <> (Container<T>& lhs, Container<T>& rhs) ^ 1 error detected in the compilation of "ComeauTest.c". I'm having a hard time trying to get Comeau/MingGW to play ball, so that's where I turn to you guys. It's been a long time since my brain has melted this much under the weight of C++ syntax, so I feel a little embarrassed ;). Thanks in advance. EDIT: Eliminated an (irrelevant) lvalue error listed in initial Comeau dump.

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• How to find an element in an array in C

  - by gkaykck

  I am trying to find the location of an element in the array. I have tried to use this code i generated for(i=0;i<10;i++) { if (strcmp(temp[0],varptr[i])==0) j=i; } varptr is a pointer which points to array var[11][10] and it is by the definition *varptr[11][10]. I have assigned strings to var[i] and i want to get the "i" number of my element NOT THE ADRESS. Thanks for any comment. EDit: temp is also a pointer which points to the string that i want to check. Also i am using the 2D array for keeping variable names and their address. So yes i want to keep it inside a 2D array. The question is this code is not working at all, it does not assigns i to j, so i wonder where is the problem with this idea? writing a "break" does not change if the code works or not, it just optimizes the code a little. Full Code: #include <stdio.h> #include <string.h> #include <ctype.h> double atof(char*); int main(void) { char in[100], *temp[10],var[11][10],*varptr[11][10]; int i,j, n = 0,fullval=0; double val[11]; strcpy(var[11], "ans"); for(i=0;i<11;i++) { for(j=0;j<10;j++) varptr[i][j]=&var[i][j]; } START: printf("Enter the expression: "); fflush(stdout); for(i=0;i<10;i++) temp[i]=NULL; if (fgets(in, sizeof in, stdin) != NULL) { temp[0] = strtok(in, " "); if (temp[0] != NULL) { for (n = 1; n < 10 && (temp[n] = strtok(NULL," ")) != NULL; n++) ; } if (*temp[0]=="quit") { goto FINISH;} if (isdigit(*temp[0])) { if (*temp[1]=='+') val[0] = atof(temp[0])+atof(temp[2]); else if (*temp[1]=='-') val[0] = atof(temp[0])-atof(temp[2]); else if (*temp[1]=='*') val[0] = atof(temp[0])*atof(temp[2]); else if (*temp[1]=='/') val[0] = atof(temp[0])/atof(temp[2]); printf("%s = %f\n",var[11],val[0]); goto START; } else if (temp[1]==NULL) //asking the value of a variable { for(i=0;i<10;i++) { if (strcmp(temp[0],varptr[i])==0) j=i; } printf("%s = %d\n",var[j],val[j]); goto START; } if (*temp[1]==61) { strcpy(var[fullval], temp[0]); if ((temp[3])!=NULL) { } val[fullval]=atof(temp[2]); printf("%s = %f\n",var[fullval],val[fullval]); fullval++; goto START; } if (*temp[1]!=61) { } } getch(); FINISH: return 0; }

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• ActionScript MovieClip moves to the left, but not the right

  - by Defcon

  I have a stage with a movie clip with the instance name of "mc". Currently I have a code that is suppose to move the player left and right, and when the left or right key is released, the "mc" slides a little bit. The problem I'm having is that making the "mc" move to the left works, but the exact some code used for the right doesn't. All of this code is present on the Main Stage - Frame One //Variables var mcSpeed:Number = 0;//MC's Current Speed var mcJumping:Boolean = false;//if mc is Jumping var mcFalling:Boolean = false;//if mc is Falling var mcMoving:Boolean = false;//if mc is Moving var mcSliding:Boolean = false;//if mc is sliding var mcSlide:Number = 0;//Stored for use when creating slide var mcMaxSlide:Number = 1.6;//Max Distance the object will slide. //Player Move Function p1Move = new Object(); p1Move = function (dir:String, maxSpeed:Number) { if (dir == "left" && _root.mcSpeed<maxSpeed) { _root.mcSpeed += .2; _root.mc._x -= _root.mcSpeed; } else if (dir == "right" && _root.mcSpeed<maxSpeed) { _root.mcSpeed += .2; _root.mc._x += _root.mcSpeed; } else if (dir == "left" && speed>=maxSpeed) { _root.mc._x -= _root.mcSpeed; } else if (dir == "right" && _root.mcSpeed>=maxSpeed) { _root.mc._x += _root.mcSpeed; } } //onEnterFrame for MC mc.onEnterFrame = function():Void { if (Key.isDown(Key.LEFT)) { if (_root.mcMoving == false && _root.mcSliding == false) { _root.mcMoving = true; } else if (_root.mcMoving == true && _root.mcSliding == false) { _root.p1Move("left",5); } } else if (!Key.isDown(Key.LEFT)) { if (_root.mcMoving == true && _root.mcSliding == false) { _root.mcSliding = true; } else if (_root.mcMoving == true && _root.mcSliding == true && _root.mcSlide<_root.mcMaxSlide) { _root.mcSlide += .2; this._x -= .2; } else if (_root.mcMoving == true && _root.mcSliding == true && _root.mcSlide>=_root.mcMaxSlide) { _root.mcMoving = false; _root.mcSliding = false; _root.mcSlide = 0; _root.mcSpeed = 0; } } else if (Key.isDown(Key.RIGHT)) { if (_root.mcMoving == false && _root.mcSliding == false) { _root.mcMoving = true; } else if (_root.mcMoving == true && _root.mcSliding == false) { _root.p1Move("right",5); } } else if (!Key.isDown(Key.RIGHT)) { if (_root.mcMoving == true && _root.mcSliding == false) { _root.mcSliding = true; } else if (_root.mcMoving == true && _root.mcSliding == true && _root.mcSlide<_root.mcMaxSpeed) { _root.mcSlide += .2; this._x += .2; } else if (_root.mcMoving == true && _root.mcSliding == true && _root.mcSlide>=_root.mcMax) { _root.mcMoving = false; _root.mcSliding = false; _root.mcSlide = 0; _root.mcSpeed = 0; } } }; I just don't get why when you press the left arrow its works completely fine, but when you press the right arrow it doesn't respond. It is literally the same code.

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• ComboBox values disappears after selected when objects used for display

  - by Gakk

  I have a combobox where I want to display objects and have enum values returned. When first opened the combobox displays the items as supposed, but after a value is chosen it seems to disappear from the list. But if the combobox is active I can use the keyboard to navigate up and down between the other values, so they are in the list but only invisible. I have created a little test application to show my problem. When started the application shows the combobox with all the choices (the two first are type of Object, the third is a String): After the blue line is selected and when the combobox is opened again this line is missing: When the line with the text "Green" is selected that line is still showing: If I had chosen the red line the only thing that would still be in the list is the test "Green". I am using .NET Framework 3.5. Any hints or tips to why the elements disappears? Here are all the code needed after starting a blank project in Visual Studio. MainWindow.xaml.cs: using System; using System.Collections.Generic; using System.Diagnostics; namespace Test { public partial class MainWindow { public MainWindow() { InitializeComponent(); } private ColorComboBoxValue _activeColor; public ColorComboBoxValue ActiveColor { get { return _activeColor; } set { _activeColor = value; Debug.WriteLine("ActiveColor: " + _activeColor.Color); } } } public class ColorList : List<ColorComboBoxValue> { } public class ColorComboBoxValue { public Color Color { get; set; } public Object Object { get; set; } } public enum Color { Red, Blue, Green } } MainWindow.xaml: <Window x:Class="Test.MainWindow" x:Name="window" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:System="clr-namespace:System;assembly=mscorlib" xmlns:local="clr-namespace:Test" Title="ComboBoxTest" Height="100" Width="200"> <Window.Resources> <local:ColorList x:Key="ColorList"> <local:ColorComboBoxValue Color="Red"> <local:ColorComboBoxValue.Object> <Path Data="M0,0 L0,30 60,30 60,0 Z" Fill="Red"/> </local:ColorComboBoxValue.Object> </local:ColorComboBoxValue> <local:ColorComboBoxValue Color="Blue"> <local:ColorComboBoxValue.Object> <Path Data="M0,0 L0,30 60,30 60,0 Z" Fill="Blue"/> </local:ColorComboBoxValue.Object> </local:ColorComboBoxValue> <local:ColorComboBoxValue Color="Green"> <local:ColorComboBoxValue.Object> <System:String>Green</System:String> </local:ColorComboBoxValue.Object> </local:ColorComboBoxValue> </local:ColorList> </Window.Resources> <ComboBox ItemsSource="{Binding Source={StaticResource ColorList}}" SelectedItem="{Binding ActiveColor, ElementName=window}"> <ComboBox.ItemTemplate> <DataTemplate> <ContentPresenter Content="{Binding Path=Object}"/> </DataTemplate> </ComboBox.ItemTemplate> </ComboBox> </Window>

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• Trying to packetize TCP with non-blocking IO is hard! Am I doing something wrong?

  - by Ricket

  Oh how I wish TCP was packet-based like UDP is! But alas, that's not the case, so I'm trying to implement my own packet layer. Here's the chain of events so far (ignoring writing packets) Oh, and my Packets are very simply structured: two unsigned bytes for length, and then byte[length] data. (I can't imagine if they were any more complex, I'd be up to my ears in if statements!) Server is in an infinite loop, accepting connections and adding them to a list of Connections. PacketGatherer (another thread) uses a Selector to figure out which Connection.SocketChannels are ready for reading. It loops over the results and tells each Connection to read(). Each Connection has a partial IncomingPacket and a list of Packets which have been fully read and are waiting to be processed. On read(): Tell the partial IncomingPacket to read more data. (IncomingPacket.readData below) If it's done reading (IncomingPacket.complete()), make a Packet from it and stick the Packet into the list waiting to be processed and then replace it with a new IncomingPacket. There are a couple problems with this. First, only one packet is being read at a time. If the IncomingPacket needs only one more byte, then only one byte is read this pass. This can of course be fixed with a loop but it starts to get sorta complicated and I wonder if there is a better overall way. Second, the logic in IncomingPacket is a little bit crazy, to be able to read the two bytes for the length and then read the actual data. Here is the code, boiled down for quick & easy reading: int readBytes; // number of total bytes read so far byte length1, length2; // each byte in an unsigned short int (see getLength()) public int getLength() { // will be inaccurate if readBytes < 2 return (int)(length1 << 8 | length2); } public void readData(SocketChannel c) { if (readBytes < 2) { // we don't yet know the length of the actual data ByteBuffer lengthBuffer = ByteBuffer.allocate(2 - readBytes); numBytesRead = c.read(lengthBuffer); if(readBytes == 0) { if(numBytesRead >= 1) length1 = lengthBuffer.get(); if(numBytesRead == 2) length2 = lengthBuffer.get(); } else if(readBytes == 1) { if(numBytesRead == 1) length2 = lengthBuffer.get(); } readBytes += numBytesRead; } if(readBytes >= 2) { // then we know we have the entire length variable // lazily-instantiate data buffers based on getLength() // read into data buffers, increment readBytes // (does not read more than the amount of this packet, so it does not // need to handle overflow into the next packet's data) } } public boolean complete() { return (readBytes > 2 && readBytes == getLength()+2); } Basically I need feedback on my code. Please suggest any improvements. Even overhauling my entire system would be okay, if you have suggestions for how better to implement the whole thing. Book recommendations are welcome too; I love books. I just get the feeling that something isn't quite right.

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• JavaScript Optimisation

  - by Jayie

  I am using JavaScript to work out all the combinations of badminton doubles matches from a given list of players. Each player teams up with everyone else. EG. If I have the following players a, b, c & d. Their combinations can be: a & b V c & d a & c V b & d a & d V b & c I am using the code below, which I wrote to do the job, but it's a little inefficient. It loops through the PLAYERS array 4 times finding every single combination (including impossible ones). It then sorts the game out into alphabetical order and stores it in the GAMES array if it doesn't already exist. I can then use the first half of the GAMES array to list all game combinations. The trouble is if I have any more than 8 players it runs really slowly because the combination growth is exponential. Does anyone know a better way or algorithm I could use? The more I think about it the more my brain hurts! var PLAYERS = ["a", "b", "c", "d", "e", "f", "g"]; var GAMES = []; var p1, p2, p3, p4, i1, i2, i3, i4, entry, found, i; var pos = 0; var TEAM1 = []; var TEAM2 = []; // loop through players 4 times to get all combinations for (i1 = 0; i1 < PLAYERS.length; i1++) { p1 = PLAYERS[i1]; for (i2 = 0; i2 < PLAYERS.length; i2++) { p2 = PLAYERS[i2]; for (i3 = 0; i3 < PLAYERS.length; i3++) { p3 = PLAYERS[i3]; for (i4 = 0; i4 < PLAYERS.length; i4++) { p4 = PLAYERS[i4]; if ((p1 != p2 && p1 != p3 && p1 != p4) && (p2 != p1 && p2 != p3 && p2 != p4) && (p3 != p1 && p3 != p2 && p3 != p4) && (p4 != p1 && p4 != p2 && p4 != p3)) { // sort teams into alphabetical order (so we can compare them easily later) TEAM1[0] = p1; TEAM1[1] = p2; TEAM2[0] = p3; TEAM2[1] = p4; TEAM1.sort(); TEAM2.sort(); // work out the game and search the array to see if it already exists entry = TEAM1[0] + " & " + TEAM1[1] + " v " + TEAM2[0] + " & " + TEAM2[1]; found = false; for (i=0; i < GAMES.length; i++) { if (entry == GAMES[i]) found = true; } // if the game is unique then store it if (!found) { GAMES[pos] = entry; document.write((pos+1) + ": " + GAMES[pos] + "<br>"); pos++; } } } } } } Thanks in advance. Jason.

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• Keeping video viewing statistics breakdown by video time in a database

  - by Septagram

  I need to keep a number of statistics about the videos being watched, and one of them is what parts of the video are being watched most. The design I came up with is to split the video into 256 intervals and keep the floating-point number of views for each of them. I receive the data as a number of intervals the user watched continuously. The problem is how to store them. There are two solutions I see. Row per every video segment Let's have a database table like this: CREATE TABLE `video_heatmap` ( `id` int(11) NOT NULL AUTO_INCREMENT, `video_id` int(11) NOT NULL, `position` tinyint(3) unsigned NOT NULL, `views` float NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `idx_lookup` (`video_id`,`position`) ) ENGINE=MyISAM Then, whenever we have to process a number of views, make sure there are the respective database rows and add appropriate values to the views column. I found out it's a lot faster if the existence of rows is taken care of first (SELECT COUNT(*) of rows for a given video and INSERT IGNORE if they are lacking), and then a number of update queries is used like this: UPDATE video_heatmap SET views = views + ? WHERE video_id = ? AND position >= ? AND position < ? This seems, however, a little bloated. The other solution I came up with is Row per video, update in transactions A table will look (sort of) like this: CREATE TABLE video ( id INT NOT NULL AUTO_INCREMENT, heatmap BINARY (4 * 256) NOT NULL, ... ) ENGINE=InnoDB Then, upon every time a view needs to be stored, it will be done in a transaction with consistent snapshot, in a sequence like this: If the video doesn't exist in the database, it is created. A row is retrieved, heatmap, an array of floats stored in the binary form, is converted into a form more friendly for processing (in PHP). Values in the array are increased appropriately and the array is converted back. Row is changed via UPDATE query. So far the advantages can be summed up like this: First approach Stores data as floats, not as some magical binary array. Doesn't require transaction support, so doesn't require InnoDB, and we're using MyISAM for everything at the moment, so there won't be any need to mix storage engines. (only applies in my specific situation) Doesn't require a transaction WITH CONSISTENT SNAPSHOT. I don't know what are the performance penalties of those. I already implemented it and it works. (only applies in my specific situation) Second approach Is using a lot less storage space (the first approach is storing video ID 256 times and stores position for every segment of the video, not to mention primary key). Should scale better, because of InnoDB's per-row locking as opposed to MyISAM's table locking. Might generally work faster because there are a lot less requests being made. Easier to implement in code (although the other one is already implemented). So, what should I do? If it wasn't for the rest of our system using MyISAM consistently, I'd go with the second approach, but currently I'm leaning to the first one. But maybe there are some reasons to favour one approach or another?

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• Trying to reinvent the wheel of StackOverflow to have a good learning experience. Need some suggesti

  - by Legend

  I want to learn and am not able to do it unless I have a real "mission" to complete. SO is my favorite and I can't imagine a better experience than actually recreating it but not in ASP. I'd like to use PHP+MySQL+jQuery. So far, I have been a self-taught programmer but I would like to master one paradigm that forces you to adhere to the standards. For instance, recently, jQuery forced me to use some "rules". The plugins were supposed to be written in a particular way and that's it. When I started off, everything seemed like Greek and Latin but when I finished a very small plugin, I felt really happy because it forced me to program in a certain way. I am looking for something like this only in a larger project. I've heard a lot about MVC and all but I am confused about the various frameworks out there. Zend seems awesome but looks heavy at the same time and also requires you to have a lot more control over the web-server whereas CakePHP is a good and a fast framework that needs only little control. Do I use one of these or just write my own MVC? I have the following goals: Goals: Site should be fast - I know this depends on my coding skills but I will learn on my way. The framework itself should not slow me down) Setting up the site should not require you to use command-line - This requirement is ok during development. But some frameworks like Symphony require you to initialize certain things through command-line Should support pluggable modules - For instance, if I want to be able to use the FCK editor, I should be able to organize things in a good way. Should be possible to extend - For instance, SO is mainly a Q&A site but I should be able to logically extend it into an Idea Management System (optional but I'm curious). This goes more into code re-usability I guess. I am comfortable with MySQL so I should be done with database design etc. with some serious effort. As for PHP, I can write code on my own but haven't really used any frameworks that much. jQuery, I started off recently and love it. I would be glad if someone can guide me during these initial steps. Precisely, when designing something like SO, I have the following questions: Do I use a framework? If yes, should it be MVC? If MVC, which one is a good and a scalable one? (I'd love something like jQuery that will not die anytime soon) How do I balance the functionality? The same logic can sometimes be made server centric or client centric. (more Ajax?). Is it a good idea to make a heavy javascript site considering the recent advances on client-side JS processing? Just in case anyone is wondering, I am not interested in commercializing any of this. I need a reason to learn something :)

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• Javascript style objects in Objective-C

  - by awolf

  Background: I use a ton of NSDictionary objects in my iPhone and iPad code. I'm sick of the verbose way of getting/setting keys to these state dictionaries. So a little bit of an experiment: I just created a class I call Remap. Remap will take any arbitrary set[VariableName]:(NSObject *) obj selector and forward that message to a function that will insert obj into an internal NSMutableDictionary under the key [vairableName]. Remap will also take any (zero argument) arbitrary [variableName] selector and return the NSObject mapped in the NSMutableDictionary under the key [variableName]. e.g. Remap * remap = [[Remap alloc] init]; NSNumber * testNumber = [NSNumber numberWithInt:46]; [remap setTestNumber:testNumber]; testNumber = [remap testNumber]; [remap setTestString:@"test string"]; NSString * testString = [remap testString]; NSMutableDictionary * testDict = [NSMutableDictionary dictionaryWithObject:testNumber forKey:@"testNumber"]; [remap setTestDict:testDict]; testDict = [remap testDict]; where none of the properties testNumber, testString, or testDict are actually defined in Remap. The crazy thing? It works... My only question is how can I disable the "may not respond to " warnings for JUST accesses to Remap? P.S. : I'll probably end up scrapping this and going with macros since message forwarding is quite inefficient... but aside from that does anyone see other problems with Remap? Here's Remap's .m for those who are curious: #import "Remap.h" @interface Remap () @property (nonatomic, retain) NSMutableDictionary * _data; @end @implementation Remap @synthesize _data; - (void) dealloc { relnil(_data); [super dealloc]; } - (id) init { self = [super init]; if (self != nil) { NSMutableDictionary * dict = [[NSMutableDictionary alloc] init]; [self set_data:dict]; relnil(dict); } return self; } - (void)forwardInvocation:(NSInvocation *)anInvocation { NSString * selectorName = [NSString stringWithUTF8String: sel_getName([anInvocation selector])]; NSRange range = [selectorName rangeOfString:@"set"]; NSInteger numArguments = [[anInvocation methodSignature] numberOfArguments]; if (range.location == 0 && numArguments == 4) { //setter [anInvocation setSelector:@selector(setData:withKey:)]; [anInvocation setArgument:&selectorName atIndex:3]; [anInvocation invokeWithTarget:self]; } else if (numArguments == 3) { [anInvocation setSelector:@selector(getDataWithKey:)]; [anInvocation setArgument:&selectorName atIndex:2]; [anInvocation invokeWithTarget:self]; } } - (NSMethodSignature *) methodSignatureForSelector:(SEL) aSelector { NSString * selectorName = [NSString stringWithUTF8String: sel_getName(aSelector)]; NSMethodSignature * sig = [super methodSignatureForSelector:aSelector]; if (sig == nil) { NSRange range = [selectorName rangeOfString:@"set"]; if (range.location == 0) { sig = [self methodSignatureForSelector:@selector(setData:withKey:)]; } else { sig = [self methodSignatureForSelector:@selector(getDataWithKey:)]; } } return sig; } - (NSObject *) getDataWithKey: (NSString *) key { NSObject * returnValue = [[self _data] objectForKey:key]; return returnValue; } - (void) setData: (NSObject *) data withKey:(NSString *)key { if (key && [key length] >= 5 && data) { NSRange range; range.length = 1; range.location = 3; NSString * firstChar = [key substringWithRange:range]; firstChar = [firstChar lowercaseString]; range.length = [key length] - 5; // the 4 we have processed plus the training : range.location = 4; NSString * adjustedKey = [NSString stringWithFormat:@"%@%@", firstChar, [key substringWithRange:range]]; [[self _data] setObject:data forKey:adjustedKey]; } else { //assert? } } @end

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• How to define template directives (from an API perspective)?

  - by Ralph

  Preface I'm writing a template language (don't bother trying to talk me out of it), and in it, there are two kinds of user-extensible nodes. TemplateTags and TemplateDirectives. A TemplateTag closely relates to an HTML tag -- it might look something like div(class="green") { "content" } And it'll be rendered as <div class="green">content</div> i.e., it takes a bunch of attributes, plus some content, and spits out some HTML. TemplateDirectives are a little more complicated. They can be things like for loops, ifs, includes, and other such things. They look a lot like a TemplateTag, but they need to be processed differently. For example, @for($i in $items) { div(class="green") { $i } } Would loop over $items and output the content with the variable $i substituted in each time. So.... I'm trying to decide on a way to define these directives now. Template Tags The TemplateTags are pretty easy to write. They look something like this: [TemplateTag] static string div(string content = null, object attrs = null) { return HtmlTag("div", content, attrs); } Where content gets the stuff between the curly braces (pre-rendered if there are variables in it and such), and attrs is either a Dictionary<string,object> of attributes, or an anonymous type used like a dictionary. It just returns the HTML which gets plunked into its place. Simple! You can write tags in basically 1 line. Template Directives The way I've defined them now looks like this: [TemplateDirective] static string @for(string @params, string content) { var tokens = Regex.Split(@params, @"\sin\s").Select(s => s.Trim()).ToArray(); string itemName = tokens[0].Substring(1); string enumName = tokens[1].Substring(1); var enumerable = data[enumName] as IEnumerable; var sb = new StringBuilder(); var template = new Template(content); foreach (var item in enumerable) { var templateVars = new Dictionary<string, object>(data) { { itemName, item } }; sb.Append(template.Render(templateVars)); } return sb.ToString(); } (Working example). Basically, the stuff between the ( and ) is not split into arguments automatically (like the template tags do), and the content isn't pre-rendered either. The reason it isn't pre-rendered is because you might want to add or remove some template variables or something first. In this case, we add the $i variable to the template variables, var templateVars = new Dictionary<string, object>(data) { { itemName, item } }; And then render the content manually, sb.Append(template.Render(templateVars)); Question I'm wondering if this is the best approach to defining custom Template Directives. I want to make it as easy as possible. What if the user doesn't know how to render templates, or doesn't know that he's supposed to? Maybe I should pass in a Template instance pre-filled with the content instead? Or maybe only let him tamper w/ the template variables, and then automatically render the content at the end? OTOH, for things like "if" if the condition fails, then the template wouldn't need to be rendered at all. So there's a lot of flexibility I need to allow in here. Thoughts?

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• How to debug KVO

  - by user8472

  In my program I use KVO manually to observe changes to values of object properties. I receive an EXC_BAD_ACCESS signal at the following line of code inside a custom setter: [self willChangeValueForKey:@"mykey"]; The weird thing is that this happens when a factory method calls the custom setter and there should not be any observers around. I do not know how to debug this situation. Update: The way to list all registered observers is observationInfo. It turned out that there was indeed an object listed that points to an invalid address. However, I have no idea at all how it got there. Update 2: Apparently, the same object and method callback can be registered several times for a given object - resulting in identical entries in the observed object's observationInfo. When removing the registration only one of these entries is removed. This behavior is a little counter-intuitive (and it certainly is a bug in my program to add multiple entries at all), but this does not explain how spurious observers can mysteriously show up in freshly allocated objects (unless there is some caching/reuse going on that I am unaware of). Modified question: How can I figure out WHERE and WHEN an object got registered as an observer? Update 3: Specific sample code. ContentObj is a class that has a dictionary as a property named mykey. It overrides: + (BOOL)automaticallyNotifiesObserversForKey:(NSString *)theKey { BOOL automatic = NO; if ([theKey isEqualToString:@"mykey"]) { automatic = NO; } else { automatic=[super automaticallyNotifiesObserversForKey:theKey]; } return automatic; } A couple of properties have getters and setters as follows: - (CGFloat)value { return [[[self mykey] objectForKey:@"value"] floatValue]; } - (void)setValue:(CGFloat)aValue { [self willChangeValueForKey:@"mykey"]; [[self mykey] setObject:[NSNumber numberWithFloat:aValue] forKey:@"value"]; [self didChangeValueForKey:@"mykey"]; } The container class has a property contents of class NSMutableArray which holds instances of class ContentObj. It has a couple of methods that manually handle registrations: + (BOOL)automaticallyNotifiesObserversForKey:(NSString *)theKey { BOOL automatic = NO; if ([theKey isEqualToString:@"contents"]) { automatic = NO; } else { automatic=[super automaticallyNotifiesObserversForKey:theKey]; } return automatic; } - (void)observeContent:(ContentObj *)cObj { [cObj addObserver:self forKeyPath:@"mykey" options:0 context:NULL]; } - (void)removeObserveContent:(ContentObj *)cObj { [cObj removeObserver:self forKeyPath:@"mykey"]; } - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { if (([keyPath isEqualToString:@"mykey"]) && ([object isKindOfClass:[ContentObj class]])) { [self willChangeValueForKey:@"contents"]; [self didChangeValueForKey:@"contents"]; } } There are several methods in the container class that modify contents. They look as follows: - (void)addContent:(ContentObj *)cObj { [self willChangeValueForKey:@"contents"]; [self observeDatum:cObj]; [[self contents] addObject:cObj]; [self didChangeValueForKey:@"contents"]; } And a couple of others that provide similar functionality to the array. They all work by adding/removing themselves as observers. Obviously, anything that results in multiple registrations is a bug and could sit somewhere hidden in these methods. My question targets strategies on how to debug this kind of situation. Alternatively, please feel free to provide an alternative strategy for implementing this kind of notification/observer pattern.

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• -Java- Swing GUI - Moving around components specifically with layouts

  - by Xemiru Scarlet Sanzenin

  I'm making a little test GUI for something I'm making. However, problems occur with the positioning of the panels. public winInit() { super("Chatterbox - Login"); try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch(ClassNotFoundException e) { } catch (InstantiationException e) { } catch (IllegalAccessException e) { } catch (UnsupportedLookAndFeelException e) { } setSize(300,135); pn1 = new JPanel(); pn2 = new JPanel(); pn3 = new JPanel(); l1 = new JLabel("Username"); l2 = new JLabel("Password"); l3 = new JLabel("Random text here"); l4 = new JLabel("Server Address"); l5 = new JLabel("No address set."); i1 = new JTextField(10); p1 = new JPasswordField(10); b1 = new JButton("Connect"); b2 = new JButton("Register"); b3 = new JButton("Set IP"); l4.setBounds(10, 12, getDim(l4).width, getDim(l4).height); l1.setBounds(10, 35, getDim(l1).width, getDim(l1).height); l2.setBounds(10, 60, getDim(l2).width, getDim(l2).height); l3.setBounds(10, 85, getDim(l3).width, getDim(l3).height); l5.setBounds(l4.getBounds().width + 14, 12, l5.getPreferredSize().width, l5.getPreferredSize().height); l5.setForeground(Color.gray); i1.setBounds(getDim(l1).width + 15, 35, getDim(i1).width, getDim(i1).height); p1.setBounds(getDim(l1).width + 15, 60, getDim(p1).width, getDim(p1).height); b1.setBounds(getDim(l1).width + getDim(i1).width + 23, 34, getDim(b2).width, getDim(b1).height - 5); b2.setBounds(getDim(l1).width + getDim(i1).width + 23, 60, getDim(b2).width, getDim(b2).height - 5); b3.setBounds(getDim(l1).width + getDim(i1).width + 23, 10, etDim(b2).width, getDim(b3).height - 5); b1.addActionListener(clickButton); b2.addActionListener(clickButton); b3.addActionListener(clickButton); pn1.setLayout(new FlowLayout(FlowLayout.RIGHT)); pn2.setLayout(new FlowLayout(FlowLayout.RIGHT)); pn1.add(l1); pn1.add(i1); pn1.add(b1); pn2.add(l2); pn2.add(p1); pn2.add(b2); add(pn1); add(pn2); } I am attempting to use FlowLayout to position the panels in the way desired. I'd use BorderLayout while adding, but the vertical spacing is too far away when I just use directions closest to one another. The output of this code is to create a window, 300,150, place whatever's in the two panels in the exact same spaces. Yes, I realize there's useless code there with setBounds(), but that was just me screwing around with Absolute Positioning, which wasn't working out for me either.

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