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• IOC/Autofac problem

  - by Krazzy

  I am currently using Autofac, but am open to commentary regarding other IOC containers as well. I would prefer a solution using Autofac if possible. I am also somewhat new to IOC so I may be grossly misunderstanding what I should be using an IOC container for. Basically, the situation is as follows: I have a topmost IOC container for my app. I have a tree of child containers/scopes where I would like the same "service" (IWhatever) to resolve differently depending on which level in the tree it is resolved. Furthermore if a service is not registered at some level in the tree I would like the tree to be transversed upward until a suitable implementation is found. Furthermore, when constructing a given component, it is quite possible that I will need access to the parent container/scope. In many cases the component that I'm registering will have a dependency on the same or a different service in a parent scope. Is there any way to express this dependency with Autofac? Something like: builder.Register(c=> { var parentComponent = ?.Resolve<ISomeService>(); var childComponent = new ConcreteService(parentComponent, args...); return childComponent; }).As<ISomeService>(); I can't get anything similar to the above pseudocode to work for serveral reasons: A) It seems that all levels in the scope tree share a common set of registrations. I can't seem to find a way to make a given registration confined a certain "scope". B) I can't seem to find a way to get a hold of the parent scope of a given scope. I CAN resolve ILifetimeScope in the container and then case it to a concrete LifetimeScope instance which provides its parent scope, but I'm guessing it is probably note meant to be used this way. Is this safe? C) I'm not sure how to tell Autofac which container owns the resolved object. For many components I would like component to be "owned" by the scope in which it is constructed. Could tagged contexts help me here? Would I have to tag every level of the tree with a unique tag? This would be difficult because the tree depth is determined at runtime. Sorry for the extremely lengthy question. In summary: 1) Is there any way to do what I want to do using Autofac? 2) Is there another container more suited to this kind of dependency structure? 3) Is IOC the wrong tool for this altogether?

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• Java loading user-specified classes at runtime

  - by user349043

  I'm working on robot simulation in Java (a Swing application). I have an abstract class "Robot" from which different types of Robots are derived, e.g. public class StupidRobot extends Robot { int m_stupidness; int m_insanityLevel; ... } public class AngryRobot extends Robot { float m_aggression; ... } As you can see, each Robot subclass has a different set of parameters. What I would like to do is control the simulation setup in the initial UI. Choose the number and type of Robots, give it a name, fill in the parameters etc. This is one of those times where being such a dinosaur programmer, and new to Java, I wonder if there is some higher level stuff/thinking that could help me here. So here is what I've got: (1) User Interface Scrolling list of Robot types on the left. "Add " and "<< Remove" buttons in the middle. Default-named scrolling list of Robots on the right. "Set Parameters" button underneath. (So if you wanted an AngryRobot, you'd select AngryRobot on the left list, click "Add" and "AngryRobot1" would show up on the right.) When selecting a Robot on the right, click "Set Parameters..." button which would call yet another model dialog where you'd fill in the parameters. Different dialog called for each Robot type. (2) Data structures an implementation As an end-product I think a HashMap would be most convenient. The keys would be Robot types and the accompanying object would be all of the parameters. The initializer could just retrieve each item one and a time and instantiate. Here's what the data structures would look like: enum ROBOT_TYPE {STUPID, ANGRY, etc} public class RobotInitializer { public ROBOT_TYPE m_type; public string m_name; public int[] m_int_params; public float[] m_float_params; etc. The initializer's constructor would create the appropriate length parameter arrays based on the type: public RobotInitializer(ROBOT_TYPE type, int[] int_array, float[] float_array, etc){ switch (type){ case STUPID: m_int_params = new int[STUPID_INT_PARAM_LENGTH]; System.arraycopy(int_array,0,m_int_params,0,STUPID_INT_PARAM_LENGTH); etc. Once all the RobotInitializers are instantiated, they are added to the HashMap. Iterating through the HashMap, the simulation initializer takes items from the Hashmap and instantiates the appropriate Robots. Is this reasonable? If not, how can it be improved? Thanks

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• php connecting to mysql server(localhost) very slow

  - by Ahmad

  actually its little complicated: summary: the connection to DB is very slow. the page rendering takes around 10 seconds but the last statement on the page is an echo and i can see its output while the page is loading in firefox (IE is same). in google chrome the output becomes visible only when the loading finishes. loading time is approximately the same across browsers. on debugging i found out that its the DB connectivity that is creating problem. the DB was on another machine. to debug further. i deployed the DB on my local machine .. so now the DB connection is at 127.0.0.1 but the connectivity still takes long time. this means that the issue is with APACHE/PHP and not with mysql. but then i deployed my code on another machine which connects to DB remotely.and everything seems fine. basically the application uses couple of mod_rewrite.. but i removed all the .htaccess files and the slow connectivity issue remains.. i installed another APACHE on my machine and used default settings. the connection was still very slow. i added following statements to measure the execution time $stime = microtime(); $stime = explode(" ",$stime); $stime = $stime[1] + $stime[0]; // my code -- it involves connection to DB $mtime = microtime(); $mtime = explode(" ",$mtime); $mtime = $mtime[1] + $mtime[0]; $totaltime = ($mtime - $stime); echo $totaltime; the output is 0.0631899833679 but firebug Net panel shows total loading time of 10-11 seconds. same is the case with google chrome i tried to turn off windows firewall.. connectivity is still slow and i just can't quite find the reason.. i've tried multiple DB servers.. multiple apaches.. nothing seems to be working.. any idea of what might be the problem?

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• OpenGL Coordinate system confusion

  - by user146780

  Maybe I set up GLUT wrong. Basically I want verticies to be reletive to their size in pixels. Ex:right now if I create a hexagon, it hakes up the whole screen even though the units are 6. #include <iostream> #include <stdlib.h> //Needed for "exit" function #include <cmath> //Include OpenGL header files, so that we can use OpenGL #ifdef __APPLE__ #include <OpenGL/OpenGL.h> #include <GLUT/glut.h> #else #include <GL/glut.h> #endif using namespace std; //Called when a key is pressed void handleKeypress(unsigned char key, //The key that was pressed int x, int y) { //The current mouse coordinates switch (key) { case 27: //Escape key exit(0); //Exit the program } } //Initializes 3D rendering void initRendering() { //Makes 3D drawing work when something is in front of something else glEnable(GL_DEPTH_TEST); } //Called when the window is resized void handleResize(int w, int h) { //Tell OpenGL how to convert from coordinates to pixel values glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); //Switch to setting the camera perspective //Set the camera perspective glLoadIdentity(); //Reset the camera gluPerspective(45.0, //The camera angle (double)w / (double)h, //The width-to-height ratio 1.0, //The near z clipping coordinate 200.0); //The far z clipping coordinate } //Draws the 3D scene void drawScene() { //Clear information from last draw glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); //Reset the drawing perspective glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glBegin(GL_POLYGON); //Begin quadrilateral coordinates //Trapezoid glColor3f(255,0,0); for(int i = 0; i < 6; ++i) { glVertex2d(sin(i/6.0*2* 3.1415), cos(i/6.0*2* 3.1415)); } glEnd(); //End quadrilateral coordinates glutSwapBuffers(); //Send the 3D scene to the screen } int main(int argc, char** argv) { //Initialize GLUT glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH); glutInitWindowSize(400, 400); //Set the window size //Create the window glutCreateWindow("Basic Shapes - videotutorialsrock.com"); initRendering(); //Initialize rendering //Set handler functions for drawing, keypresses, and window resizes glutDisplayFunc(drawScene); glutKeyboardFunc(handleKeypress); glutReshapeFunc(handleResize); glutMainLoop(); //Start the main loop. glutMainLoop doesn't return. return 0; //This line is never reached } How can I make it so that a polygon of 0,0 10,0 10,10 0,10 defines a polygon starting at the top left of the screen and is a width and height of 10 pixels? Thanks

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• How to pass operators as parameters

  - by Rodion Ingles

  I have to load an array of doubles from a file, multiply each element by a value in a table (different values for different elements), do some work on it, invert the multiplication (that is, divide) and then save the data back to file. Currently I implement the multiplication and division process in two separate methods. Now there is some extra work behind the scenes but apart from the specific statements where the multiplication/division occurs, the rest of the code is identical. As you can imagine, with this approach you have to be very careful making any changes. The surrounding code is not trivial, so its either a case of manually editing each method or copying changes from one method to the other and remembering to change the * and / operators. After too many close calls I am fed up of this and would like to make a common function which implements the common logic and two wrapper functions which pass which operator to use as a parameter. My initial approach was to use function pointers: MultiplyData(double data) { TransformData(data, &(operator *)); } DivideData(double data) { TransformData(data, &(operator /)); } TransformData(double data, double (*func)(double op1, double op2)) { /* Do stuff here... */ } However, I can't pass the operators as pointers (is this because it is an operator on a native type?), so I tried to use function objects. Initially I thought that multiplies and divides functors in <functional> would be ideal: MultiplyData(double data) { std::multiplies<double> multFunct; TransformData(data, &multFunct); } DivideData(double data) { std::divides<double> divFunct; TransformData(data, &divFunct); } TransformData(double data, std::binary_function<double, double, double> *funct) { /* Do stuff here... */ } As you can see I was trying to use a base class pointer to pass the functor polymorphically. The problem is that std::binary_function does not declare an operator() member for the child classes to implement. Is there something I am missing, or is the solution to implement my own functor heirarchy (which really seems more trouble than it is worth)?

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• how to set objectForKey to UISwitch to access switch for save selected option

  - by Rkm

  SystemUIViewcontroller has button event. Tap on Button fire InfoTableviewController. InfoTableview has UISwitch. How to set objectForKey to Info to access UIswitch ViewDidload of System... - (void)viewDidLoad { [super viewDidLoad]; self.Infoarray = [NSMutableArray array]; Info *info = [[Info alloc]initWithNibName:@"Info" bundle:nil]; [self.Infoarray addObject:[NSDictionary dictionaryWithObjectsAndKeys:info, @"viewController", nil]]; } SystemUIviewcontroller button event... -(IBAction) Info_Button_Clicked:(id) sender { Info *info = [[Info alloc]initWithNibName:@"Info" bundle:[NSBundle mainBundle]]; [self.navigationController pushViewController:info animated:YES]; [info release]; } Here for Info TableviewController... - (void)viewDidLoad { [super viewDidLoad]; self.Soundarray = [NSArray arrayWithObjects: [NSDictionary dictionaryWithObjectsAndKeys: @"Sounds", @"labelKey", self.SoundsswitchCtl, @"viewKey", nil],nil]; } // Customize the appearance of table view cells. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = nil; if ([indexPath section] == 0) { static NSString *kDisplayCell_ID = @"DisplayCellID"; cell = [self.tableView dequeueReusableCellWithIdentifier: kDisplayCell_ID]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier: kDisplayCell_ID] autorelease]; cell.selectionStyle = UITableViewCellSelectionStyleNone; } else { // the cell is being recycled, remove old embedded controls UIView *viewToRemove = nil; viewToRemove = [cell.contentView viewWithTag:1]; if (viewToRemove) [viewToRemove removeFromSuperview]; } cell.textLabel.text = [[self.Soundarray objectAtIndex: indexPath.row] valueForKey:@"labelKey"]; UIControl *control = [[self.Soundarray objectAtIndex: indexPath.row] valueForKey:@"viewKey"]; [cell.contentView addSubview:control]; return cell; } } - (UISwitch *)SoundsswitchCtl { if (SoundsswitchCtl == nil) { CGRect frame = CGRectMake(198.0, 12.0, 94.0, 27.0); SoundsswitchCtl = [[UISwitch alloc] initWithFrame:frame]; [SoundsswitchCtl addTarget:self action:@selector(switch_Sounds:) forControlEvents:UIControlEventValueChanged]; // in case the parent view draws with a custom color or gradient, use a transparent color SoundsswitchCtl.backgroundColor = [UIColor clearColor]; [SoundsswitchCtl setAccessibilityLabel:NSLocalizedString(@"StandardSwitch", @"")]; SoundsswitchCtl.tag = 1; // tag this view for later so we can remove it from recycled table cells } return SoundsswitchCtl; }

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• Urgent help needed on How to update NSMutableDictionary. My code doesn't work.

  - by dawatson833

  I've populated an array using. arrSettings = [[NSMutableArray alloc] initWithContentsOfFile:[self settingsPath]]; The file is a plist with the root as an array and then a dictionary with three three keys defined as number. I've also tried setting the keys to string. I display the values in the plist file on a view using. diaper = [[arrSettings objectAtIndex:0] objectForKey:@"Diaper Expenses"]; oil = [[arrSettings objectAtIndex:0] objectForKey:@"Oil Used"]; tree = [[arrSettings objectAtIndex:0] objectForKey:@"Wood Used"]; This code works fine, the values in the dictionary are assigned to the variables and they are displayed. The user can make changes and then press a save button. I use this code to extract the dictionary part of the array so I can update it. The assignment to editDictionary works. I've double checked the key names including case and that is correct. editDictionary = [[NSMutableDictionary alloc] init]; editDictionary = [arrSettings objectAtIndex:0]; NSNumber *myNumber = [NSNumber numberWithFloat:diaperAmount]; [editDictionary setValue:myNumber forKey:@"Diaper Expenses"]; myNumber = [NSNumber numberWithFloat:oilAmount]; [editDictionary setValue:myNumber forKey:@"Oil Used"]; myNumber = [NSNumber numberWithFloat:treeAmount]; [editDictionary setValue:myNumber forKey:@"Wood Used"]; In this example I've used a nsnumber. But I've also tried the xxxAmount field as part of SetValue instead of creating a NSNumber. Neither implementation works. Several strange things happen. Sometimes the first two setvalue statements work, but the last setvalue fails with a EXC_BAD_ACCESS failure. Other times the first setValue fails with the same error. I have no idea why the first two sometimes work. I'm at a loss of what to do next. I've tried several implentations and none of them work. Also, in the debugger how can I display the editDictionary elements. I can see editDictionary, but I don't know how to display the individual elements.

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• CSS Graph- Bars not showing correctly

  - by Olivia

  I'm trying to create a CSS/HTML based graph using this tutorial here. However instead of putting the data directly into the html code I'm importing it from a CSV file using PHP with the following code. <?PHP /* Open CSV file */ $handle = fopen("defects.csv", "r"); $c = 0; /* gets data from csv file */ while (($data = fgetcsv($handle, 1000, ",")) !== FALSE) { /* stores dates as variable $date */ $date[$c] = $data[0]; $c++; /* inserts defect data into html code */ echo "<dd class=\"p" . $data[2] . "\"><span><b>" . $data[2] . "</b></span></dd>"; echo "<dd class=\"sub p" . $data[3] . "\" ><span><b>" . $data[3] . "</b></span></dd>"; } echo "</dl>"; echo "<ul class=\"xAxis\">"; /* X AXIS */ /* inserts date data into html code for x axis */ for ($d=0; $d < $c; $d++) { echo "<li>" . $date[$d] . "</li>"; } ?> The values are being placed correctly on the chart, but the bars aren't appearing. The CSS code I have for the bars is: /* default column styling */ dl#csschart span{ height:50%; background:url(../images/barx.png) repeat-y; } dl#csschart .sub{ margin-left:-33px; } dl#csschart .sub span{ background:url(../images/subBarx.png) repeat-y; } Just in case it helps, I've print screened how the graph should look. You can see it at: http://allured.info/graph/failgraph.png

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• [Reloaded] Error while sorting filtered data from a GridView

  - by Bogdan M

  Hello guys, I have an error I cannot solve, on a ASP.NET website. One of its pages - Countries.aspx, has the following controls: a CheckBox called "CheckBoxNAME": < asp:CheckBox ID="CheckBoxNAME" runat="server" Text="Name" /> a TextBox called "TextBoxName": < asp:TextBox ID="TextBoxNAME" runat="server" Width="100%" Wrap="False"> < /asp:TextBox> a SQLDataSource called "SqlDataSourceCOUNTRIES", that selects all records from a Table with 3 columns - ID (Number, PK), NAME (Varchar2(1000)), and POPULATION (Number) called COUNTRIES < asp:SqlDataSource ID="SqlDataSourceCOUNTRIES" runat="server" ConnectionString="< %$ ConnectionStrings:myDB %> " ProviderName="< %$ ConnectionStrings:myDB.ProviderName %> " SelectCommand="SELECT COUNTRIES.ID, COUNTRIES.NAME, COUNTRIES.POPULATION FROM COUNTRIES ORDER BY COUNTRIES.NAME, COUNTRIES.ID"> < /asp:SqlDataSource> a GridView called GridViewCOUNTRIES: < asp:GridView ID="GridViewCOUNTRIES" runat="server" AllowPaging="True" AllowSorting="True" AutoGenerateColumns="False" DataSourceID="SqlDataSourceCOUNTRIES" DataKeyNames="ID" DataMember="DefaultView"> < Columns> < asp:CommandField ShowSelectButton="True" /> < asp:BoundField DataField="ID" HeaderText="Id" SortExpression="ID" /> < asp:BoundField DataField="NAME" HeaderText="Name" SortExpression="NAME" /> < asp:BoundField DataField="POPULATION" HeaderText="Population" SortExpression="POPULATION" /> < /Columns> < /asp:GridView> a Button called ButtonFilter: < asp:Button ID="ButtonFilter" runat="server" Text="Filter" onclick="ButtonFilter_Click"/> This is the onclick event: protected void ButtonFilter_Click(object sender, EventArgs e) { Response.Redirect("Countries.aspx?" + (this.CheckBoxNAME.Checked ? string.Format("NAME={0}", this.TextBoxNAME.Text) : string.Empty)); } Also, this is the main onload event of the page: protected void Page_Load(object sender, EventArgs e) { if (Page.IsPostBack == false) { if (Request.QueryString.Count != 0) { Dictionary parameters = new Dictionary(); string commandTextFormat = string.Empty; if (Request.QueryString["NAME"] != null) { if (commandTextFormat != string.Empty && commandTextFormat.EndsWith("AND") == false) { commandTextFormat += "AND"; } commandTextFormat += " (UPPER(COUNTRIES.NAME) LIKE '%' || :NAME || '%') "; parameters.Add("NAME", Request.QueryString["NAME"].ToString()); } this.SqlDataSourceCOUNTRIES.SelectCommand = string.Format("SELECT COUNTRIES.ID, COUNTRIES.NAME, COUNTRIES.POPULATION FROM COUNTRIES WHERE {0} ORDER BY COUNTRIES.NAME, COUNTRIES.ID", commandTextFormat); foreach (KeyValuePair parameter in parameters) { this.SqlDataSourceCOUNTRIES.SelectParameters.Add(parameter.Key, parameter.Value.ToUpper()); } } } } Basicly, the page displays in the GridViewCOUNTRIES all the records of table COUNTRIES. The scenario is the following: - the user checks the CheckBox; - the user types a value in the TextBox (let's say "ch"); - the user presses the Button; - the page loads displaying only the records that match the filter criteria (in this case, all the countries that have names containing "Ch"); - the user clicks on the header of the column called "Name" in order to sort the data in the GridView Then, I get the following error: ORA-01036: illegal variable name/number. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.OracleClient.OracleException: ORA-01036: illegal variable name/number Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Any help is greatly appreciated, tnks. PS: I'm using ASP.NET 3.5, under Visual Studio 2008, with an OracleXE database.

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• How to Integrate C++ compiler in Visual Studio 2008

  - by Kasun

  Hi Can someone help me with this issue? I currently working on my project for final year of my honors degree. And we are developing a application to evaluate programming assignments of student ( for 1st year student level) I just want to know how to integrate C++ compiler using C# code to compile C++ code. In our case we are loading a student C++ code into text area, then with a click on button we want to compile the code. And if there any compilation errors it will be displayed on text area nearby. (Interface is attached herewith.) And finally it able to execute the code if there aren't any compilation errors. And results will be displayed in console. We were able to do this with a C#(C# code will be loaded to text area intead of C++ code) code using inbuilt compiler. But still not able to do for C# code. Can anyone suggest a method to do this? It is possible to integrate external compiler to VS C# code? If possible how to achieve it? Very grateful if anyone will contributing to solve this matter? This is code for Build button which we proceed with C# code compiling CodeDomProvider codeProvider = CodeDomProvider.CreateProvider("csharp"); string Output = "Out.exe"; Button ButtonObject = (Button)sender; rtbresult.Text = ""; System.CodeDom.Compiler.CompilerParameters parameters = new CompilerParameters(); //Make sure we generate an EXE, not a DLL parameters.GenerateExecutable = true; parameters.OutputAssembly = Output; CompilerResults results = codeProvider.CompileAssemblyFromSource(parameters, rtbcode.Text); if (results.Errors.Count > 0) { rtbresult.ForeColor = Color.Red; foreach (CompilerError CompErr in results.Errors) { rtbresult.Text = rtbresult.Text + "Line number " + CompErr.Line + ", Error Number: " + CompErr.ErrorNumber + ", '" + CompErr.ErrorText + ";" + Environment.NewLine + Environment.NewLine; } } else { //Successful Compile rtbresult.ForeColor = Color.Blue; rtbresult.Text = "Success!"; //If we clicked run then launch our EXE if (ButtonObject.Text == "Run") Process.Start(Output); // Run button }

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• small scale web site - global javascript file style/format/pattern - improving maintainability

  - by yaya3

  I frequently create (and inherit) small to medium websites where I have the following sort of code in a single file (normally named global.js or application.js or projectname.js). If functions get big, I normally put them in a seperate file, and call them at the bottom of the file below in the $(document).ready() section. If I have a few functions that are unique to certain pages, I normally have another switch statement for the body class inside the $(document).ready() section. How could I restructure this code to make it more maintainable? Note: I am less interested in the functions innards, more so the structure, and how different types of functions should be dealt with. I've also posted the code here - http://pastie.org/999932 in case it makes it any easier var ProjectNameEnvironment = {}; function someFunctionUniqueToTheHomepageNotWorthMakingConfigurable () { $('.foo').hide(); $('.bar').click(function(){ $('.foo').show(); }); } function functionThatIsWorthMakingConfigurable(config) { var foo = config.foo || 700; var bar = 200; return foo * bar; } function globallyRequiredJqueryPluginTrigger (tooltip_string) { var tooltipTrigger = $(tooltip_string); tooltipTrigger.tooltip({ showURL: false ... }); } function minorUtilityOneLiner (selector) { $(selector).find('li:even').not('li ul li').addClass('even'); } var Lightbox = {}; Lightbox.setup = function(){ $('li#foo a').attr('href','#alpha'); $('li#bar a').attr('href','#beta'); } Lightbox.init = function (config){ if (typeof $.fn.fancybox =='function') { Lightbox.setup(); var fade_in_speed = config.fade_in_speed || 1000; var frame_height = config.frame_height || 1700; $(config.selector).fancybox({ frameHeight : frame_height, callbackOnShow: function() { var content_to_load = config.content_to_load; ... }, callbackOnClose : function(){ $('body').height($('body').height()); } }); } else { if (ProjectNameEnvironment.debug) { alert('the fancybox plugin has not been loaded'); } } } // ---------- order of execution ----------- $(document).ready(function () { urls = urlConfig(); (function globalFunctions() { $('.tooltip-trigger').each(function(){ globallyRequiredJqueryPluginTrigger(this); }); minorUtilityOneLiner('ul.foo') Lightbox.init({ selector : 'a#a-lightbox-trigger-js', ... }); Lightbox.init({ selector : 'a#another-lightbox-trigger-js', ... }); })(); if ( $('body').attr('id') == 'home-page' ) { (function homeFunctions() { someFunctionUniqueToTheHomepageNotWorthMakingConfigurable (); })(); } });

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• Perl - Calling subclass constructor from superclass (OO)

  - by Emmel

  This may turn out to be an embarrassingly stupid question, but better than potentially creating embarrassingly stupid code. :-) This is an OO design question, really. Let's say I have an object class 'Foos' that represents a set of dynamic configuration elements, which are obtained by querying a command on disk, 'mycrazyfoos -getconfig'. Let's say that there are two categories of behavior that I want 'Foos' objects to have: Existing ones: one is, query ones that exist in the command output I just mentioned (/usr/bin/mycrazyfoos -getconfig`. Make modifications to existing ones via shelling out commands. Create new ones that don't exist; new 'crazyfoos', using a complex set of /usr/bin/mycrazyfoos commands and parameters. Here I'm not really just querying, but actually running a bunch of system() commands. Affecting changes. Here's my class structure: Foos.pm package Foos, which has a new($hashref-{name = 'myfooname',) constructor that takes a 'crazyfoo NAME' and then queries the existence of that NAME to see if it already exists (by shelling out and running the mycrazyfoos command above). If that crazyfoo already exists, return a Foos::Existing object. Any changes to this object requires shelling out, running commands and getting confirmation that everything ran okay. If this is the way to go, then the new() constructor needs to have a test to see which subclass constructor to use (if that even makes sense in this context). Here are the subclasses: Foos/Existing.pm As mentioned above, this is for when a Foos object already exists. Foos/Pending.pm This is an object that will be created if, in the above, the 'crazyfoo NAME' doesn't actually exist. In this case, the new() constructor above will be checked for additional parameters, and it will go ahead and, when called using -create() shell out using system() and create a new object... possibly returning an 'Existing' one... OR As I type this out, I am realizing it is perhaps it's better to have a single: (an alternative arrangement) Foos class, that has a -new() that takes just a name -create() that takes additional creation parameters -delete(), -change() and other params that affect ones that exist; that will have to just be checked dynamically. So here we are, two main directions to go with this. I'm curious which would be the more intelligent way to go.

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• Tab Bar disappears below the bottom of the screen

  - by Manu

  Hi, In my application I'm using a Navigation Controller to push one view that loads a Tab Bar Controller and a custom Navigation Bar as well. The problem is that the Tab Bar disappears below the bottom of the screen, and I don't know what's causing the problem. If I load a simple Tab Bar in the next view, it positions itself correctly... but what I need is a Tab Bar Controller, and in that case the Tab Bar disappears below the bottom. I have tried changing the view and size properties of the Tab Bar, but that did not solve the problem. I also realised that the images and text of the tabs don't show (I have set up the "favourites" and "contacts" images and text, and they are big enough and should be visible on the top side of the tab, but they are not). Both tabs work perfectly, by the way. There is an image here. I load the Tab Bar with the following code: - (void)viewDidLoad { [super viewDidLoad]; myTabBarController = [[UITabBarController alloc] init]; SettingsViewController* tab1 = [[SettingsViewController alloc] init]; AboutViewController* tab2 = [[AboutViewController alloc] init]; NSArray* controllers = [NSArray arrayWithObjects:tab1, tab2, nil]; myTabBarController.viewControllers = controllers; [self.view insertSubview:myTabBarController.view belowSubview:myNavigationBar]; } It doesn't matter if I remove the Navigation Bar or not. I have tested using this instead: [self.view addSubview:myTabBarController.view]; ... forgetting about the Navigation Bar, but the Tab Bar still goes under the bottom. I don't know if the problem is in one of my NIB files or in how I load the view (although I do this as I read in the Apple's SDK documentation). Any ideas? Another question would be... do you know how could I change the title of my Navigation Bar when I select the second tab? I imagine I would have to do it in viewDidLoad in AboutViewController.m, would that be correct? Thanks for you time!

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• Advice on "Invalid Pointer Operation" when using complex records

  - by Xaz

  Env: Delphi 2007 <JustificationI tend to use complex records quite frequently as they offer almost all of the advantages of classes but with much simpler handling.</Justification Anyhoo, one particularly complex record I have just implemented is trashing memory (later leading to an "Invalid Pointer Operation" error). This is an example of the memory trashing code: sSignature := gProfiles.Profile[_stPrimary].Signature.Formatted(True); On the second time i call it i get "Invalid Pointer Operation" It works OK if i call it like this: AProfile := gProfiles.Profile[_stPrimary]; ASignature := AProfile.Signature; sSignature := ASignature.Formatted(True); Background Code: gProfiles: TProfiles; TProfiles = Record private FPrimaryProfileID: Integer; FCachedProfile: TProfile; ... public < much code removed > property Profile[ProfileType: TProfileType]: TProfile Read GetProfile; end; function TProfiles.GetProfile(ProfileType: TProfileType): TProfile; begin case ProfileType of _stPrimary : Result := ProfileByID(FPrimaryProfileID); ... end; end; function TProfiles.ProfileByID(iID: Integer): TProfile; begin <snip> if LoadProfileOfID(iID, FCachedProfile) then begin Result := FCachedProfile; end else ... end; TProfile = Record private ... public ... Signature: TSignature; ... end; TSignature = Record private public PlainTextFormat : string; HTMLFormat : string; // The text to insert into a message when using this profile function Formatted(bHTML: boolean): string; end; function TSignature.Formatted(bHTML: boolean): string; begin if bHTML then result := HTMLFormat else result := PlainTextFormat; < SNIP MUCH CODE > end; OK, so I have a record within a record within a record, which is approaching Inception level confusion and I'm the first to admit is not really a good model. Clearly i am going to have to restructure it. What I would like from you gurus is a better understanding of why it is trashing the memory (something to do with the string object that is created then freed...) so that i can avoid making these kinds of errors in future. Thanks

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• What are the rules governing how a bind variable can be used in Postgres and where is this defined?

  - by Craig Miles

  I can have a table and function defined as: CREATE TABLE mytable ( mycol integer ); INSERT INTO mytable VALUES (1); CREATE OR REPLACE FUNCTION myfunction (l_myvar integer) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol = l_myvar; RETURN l_myrow; END; $$ LANGUAGE plpgsql; In this case l_myvar acts as a bind variable for the value passed when I call: SELECT * FROM myfunction(1); and returns the row where mycol = 1 If I redefine the function as: CREATE OR REPLACE FUNCTION myfunction (l_myvar integer) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol IN (l_myvar); RETURN l_myrow; END; $$ LANGUAGE plpgsql; SELECT * FROM myfunction(1); still returns the row where mycol = 1 However, if I now change the function definition to allow me to pass an integer array and try to this array in the IN clause, I get an error: CREATE OR REPLACE FUNCTION myfunction (l_myvar integer[]) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol IN (array_to_string(l_myvar, ',')); RETURN l_myrow; END; $$ LANGUAGE plpgsql; Analysis reveals that although: SELECT array_to_string(ARRAY[1, 2], ','); returns 1,2 as expected SELECT * FROM myfunction(ARRAY[1, 2]); returns the error operator does not exist: integer = text at the line: WHERE mycol IN (array_to_string(l_myvar, ',')); If I execute: SELECT * FROM mytable WHERE mycol IN (1,2); I get the expected result. Given that array_to_string(l_myvar, ',') evaluates to 1,2 as shown, why arent these statements equivalent. From the error message it is something to do with datatypes, but doesnt the IN(variable) construct appear to be behaving differently from the = variable construct? What are the rules here? I know that I could build a statement to EXECUTE, treating everything as a string, to achieve what I want to do, so I am not looking for that as a solution. I do want to understand though what is going on in this example. Is there a modification to this approach to make it work, the particular example being to pass in an array of values to build a dynamic IN clause without resorting to EXECUTE? Thanks in advance Craig

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• Error:A generic error occurred in GDI+

  - by sanfra1983

  Hi, I created a web project on the server, and when I upload an image shows me the error Error: A generic error occurred in GDI +. I have read many links on the net that talk about this issue, and although I made the changes, nothing went wrong. I was thinking if the case is not an issue of permissions to folders. In fact I have two folders one inside the other. This is the code to resize the image: public Bitmaps ResizeImage (Stream stream, int? width, int? height) ( System.Drawing.Bitmap bmpOut = null; const int defaultWidth = 800; const int defaultHeight = 600; int width = lnWidth == null? defaultWidth: (int) width; int height = lnHeight == null? defaultHeight: (int) height; try ( LoBMP bitmap = new Bitmap (stream); ImageFormat loFormat = loBMP.RawFormat; decimal lnRatio; lnNewWidth int = 0; lnNewHeight int = 0; if (loBMP.Width <& & lnWidth loBMP.Height <lnHeight) ( loBMP return; ) if (loBMP.Width> loBMP.Height) ( lnRatio = (decimal) lnWidth / loBMP.Width; lnNewWidth = lnWidth; decimal = lnTemp loBMP.Height lnRatio *; lnNewHeight = (int) lnTemp; ) else ( lnRatio = (decimal) lnHeight / loBMP.Height; lnNewHeight = lnHeight; decimal = lnTemp loBMP.Width lnRatio *; lnNewWidth = (int) lnTemp; ) bmpOut = new Bitmap (lnNewWidth, lnNewHeight); Graphics g = Graphics.FromImage (bmpOut); g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.FillRectangle (Brushes.White, 0, 0, lnNewWidth, lnNewHeight); g.DrawImage (loBMP, 0, 0, lnNewWidth, lnNewHeight); loBMP.Dispose (); ) catch ( return null; ) bmpOut return; ) and this is the code that I insert in the codebehind: string filepath = AppDomain.CurrentDomain.BaseDirectory + img_veterinario / "; string = filepathM AppDomain.CurrentDomain.BaseDirectory + img_veterinario / img_veterinarioM; Reseize Reseize R = new (); Bitmap = photosFileOriginal r.ResizeImage (fucasiclinici.PostedFile.InputStream, 400, 400); Bitmap = photosFileMiniatura r.ResizeImage (fucasiclinici.PostedFile.InputStream, 72, 72); String filename = Path.GetFileName (fucasiclinici.PostedFile.FileName); photosFileOriginal.Save (Path.Combine (filepath, filename)); photosFileMiniatura.Save (Path.Combine (filepathM, filename)); Can you help me? Thanks

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• help me to choose the best soulotion for my purpose to build my software.

  - by rima

  before answer me plz thinking about the futures of these kind of program and answer me plz. I wanna get some data from oracle server like: 1-get all the function,package,procedure and etc for showing them or drop them & etc... 2-compile my *.sql files,get the result if they have problem & etc... becuz I was beginner in oracle first of all I for solve the second problem I try to connect to sqlPlus by RUN sqlplus and trace the output(I mean,I change the output stream of shell and trace what happend and handle the assigned message to customer. NOW THIS PART SUCCEED. just a little bit I have problem with get all result because the output is asynchronous.any way... [in this case I log in to oracle Server by send argument to the sqlplus by make a process in c#] after that I try to get all function,package or procedure name,but I have problem in speed!so I try to use oracle.DataAccess.dll to connect the database. now I m so confusing about: which way is correct way to build a program that work like Oracle Developer! I do not have any experience for like these program how work. If Your answer is I must use the second way follow this part plz: I search a little bit the Golden,PLedit (Benthic software),I have little bit problem how I must create the connection string?because I thinking about how I can find the host name or port number that oracle work on them?? am I need read the TNSNames.Ora file? IF your answer is I must use the first way follow this part plz: do u have any Idea for how I parse the output?because for example the result of a table is so confusing...[i can handle & program it but I really need someone experience,because the important things to me learn how such software work so nice and with quick response?] All of the has different style in output... If you are not sure Can u help me which book can help me in this way i become expert? becuz for example all the C# write just about how u can connect to DB and the DB books write how u can use this DB program,I looking for a book that give me some Idea how develop an interface for do transaction between these two.not simple send and receive data,for example how write a compiler for them. the language of book is not different for me i know C#,java,VB,sql,Oracle Thanks.

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• How to handle very frequent updates to a Lucene index

  - by fsm

  I am trying to prototype an indexing/search application which uses very volatile indexing data sources (forums, social networks etc), here are some of the performance requirements, Very fast turn-around time (by this I mean that any new data (such as a new message on a forum) should be available in the search results very soon (less than a minute)) I need to discard old documents on a fairly regular basis to ensure that the search results are not dated. Last but not least, the search application needs to be responsive. (latency on the order of 100 milliseconds, and should support at least 10 qps) All of the requirements I have currently can be met w/o using Lucene (and that would let me satisfy all 1,2 and 3), but I am anticipating other requirements in the future (like search relevance etc) which Lucene makes easier to implement. However, since Lucene is designed for use cases far more complex than the one I'm currently working on, I'm having a hard time satisfying my performance requirements. Here are some questions, a. I read that the optimize() method in the IndexWriter class is expensive, and should not be used by applications that do frequent updates, what are the alternatives? b. In order to do incremental updates, I need to keep committing new data, and also keep refreshing the index reader to make sure it has the new data available. These are going to affect 1 and 3 above. Should I try duplicate indices? What are some common approaches to solving this problem? c. I know that Lucene provides a delete method, which lets you delete all documents that match a certain query, in my case, I need to delete all documents which are older than a certain age, now one option is to add a date field to every document and use that to delete documents later. Is it possible to do range queries on document ids (I can create my own id field since I think that the one created by lucene keeps changing) to delete documents? Is it any faster than comparing dates represented as strings? I know these are very open questions, so I am not looking for a detailed answer, I will try to treat all of your answers as suggestions and use them to inform my design. Thanks! Please let me know if you need any other information.

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• Relocating html elements with jquery

  - by Steven

  Could someone help me with this code? I'm trying to rearrange figures in a certain div into two columns (a and b) in such a way the two columns are about the same height. I've got insane trying to find the problem in my code and not finding it. It doesn't work for a reason... <body onload="rearrangeImages();"> <div class="images"> <figure> <figcaption>This is the figcaption of this figure. An image is missing for this test.</figcaption> </figure> <figure> <figcaption>This is the figcaption of this figure.</figcaption> </figure> <figure> <figcaption>Another one.</figcaption> </figure> </div> <script> function rearrangeImages() { $('.images').each(function() { $(this).prepend('<div class="column_b"></div>'); $(this).prepend('<div class="column_a"></div>'); $(this).append('<div class="test_div"></div>'); $('figure', this).each(function() { var height_a = $(this).parent().$(".column_a").height(); var height_b = $(this).parent().$(".column_b").height(); if (height_a > height_b) { $(this).parent().$(".column_b").append(this); } else { $(this).parent().$(".column_a").append(this); } $(this).remove(); }); }); } </script> </body> Next I would like to be able to make the last figure not going in any of the columns in case it would make column_b higher than column_a. (pseudocode) if (this is last figure) { //place last figure in test_div to measure its height; if (height_a > height_b + height_of_last_image) { $(this).parent().$(".column_b").append(this); } else { $(this).parent().append(this); } } else { //do the normal stuff see higher }

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• Avoiding explicit recursion in Haskell

  - by Travis Brown

  The following simple function applies a given monadic function iteratively until it hits a Nothing, at which point it returns the last non-Nothing value. It does what I need, and I understand how it works. lastJustM :: (Monad m) => (a -> m (Maybe a)) -> a -> m a lastJustM g x = g x >>= maybe (return x) (lastJustM g) As part of my self-education in Haskell I'm trying to avoid explicit recursion (or at least understand how to) whenever I can. It seems like there should be a simple non-explicitly recursive solution in this case, but I'm having trouble figuring it out. I don't want something like a monadic version of takeWhile, since it could be expensive to collect all the pre-Nothing values, and I don't care about them anyway. I checked Hoogle for the signature and nothing shows up. The m (Maybe a) bit makes me think a monad transformer might be useful here, but I don't really have the intuitions I'd need to come up with the details (yet). It's probably either embarrassingly easy to do this or embarrassingly easy to see why it can't or shouldn't be done, but this wouldn't be the first time I've used self-embarrassment as a pedagogical strategy. Background: Here's a simplified working example for context: suppose we're interested in random walks in the unit square, but we only care about points of exit. We have the following step function: randomStep :: (Floating a, Ord a, Random a) => a -> (a, a) -> State StdGen (Maybe (a, a)) randomStep s (x, y) = do (a, gen') <- randomR (0, 2 * pi) <$> get put gen' let (x', y') = (x + s * cos a, y + s * sin a) if x' < 0 || x' > 1 || y' < 0 || y' > 1 then return Nothing else return $ Just (x', y') Something like evalState (lastJustM (randomStep 0.01) (0.5, 0.5)) <$> newStdGen will give us a new data point.

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• What does Apache need to support both mysqli and PDO?

  - by Nathan Long

  I'm considering changing some PHP code to use PDO for database access instead of mysqli (because the PDO syntax makes more sense to me and is database-agnostic). To do that, I'd need both methods to work while I'm making the changeover. My problem is this: so far, either one or the other method will crash Apache. Right now I'm using XAMPP in Windows XP, and PHP Version 5.2.8. Mysqli works fine, and so does this: $dbc = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password); echo 'Connected to database'; $sql = "SELECT * FROM `employee`"; But this line makes Apache crash: $dbc->query($sql); I don't want to redo my entire Apache or XAMPP installation, but I'd like for PDO to work. So I tried updating libmysql.dll from here, as oddvibes recommended here. That made my simple PDO query work, but then mysqli queries crashed Apache. (I also tried the suggestion after that one, to update php_pdo_mysql.dll and php_pdo.dll, to no effect.) Test Case I created this test script to compare PDO vs mysqli. With the old copy of libmysql.dll, it crashes if $use_pdo is true and doesn't if it's false. With the new copy of libmysql.dll, it's the opposite. if ($use_pdo){ $dbc = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password); echo 'Connected to database<br />'; $sql = "SELECT * FROM `employee`"; $dbc->query($sql); foreach ($dbc->query($sql) as $row){ echo $row['firstname'] . ' ' . $row['lastname'] . "<br>\n"; } } else { $dbc = @mysqli_connect($hostname, $username, $password, $dbname) OR die('Could not connect to MySQL: ' . mysqli_connect_error()); $sql = "SELECT * FROM `employee`"; $result = @mysqli_query($dbc, $sql) or die(mysqli_error($dbc)); while ($row = mysqli_fetch_array($result,MYSQLI_ASSOC)) { echo $row['firstname'] . ' ' . $row['lastname'] . "<br>\n"; } } What does Apache need in order to support both methods of database query?

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• Is it correct or incorrect for a Java JAR to contain its own dependencies?

  - by 4herpsand7derpsago

  I guess this is a two-part question. I am trying to write my own Ant task (MyFirstTask) that can be used in other project's build.xml buildfiles. To do this, I need to compile and package my Ant task inside its own JAR. Because this Ant task that I have written is fairly complicated, it has about 20 dependencies (other JAR files), such as using XStream for OX-mapping, Guice for DI, etc. I am currently writing the package task in the build.xml file inside the MyFirstTask project (the buildfile that will package myfirsttask.jar, which is the reusable Ant task). I am suddenly realizing that I don't fully understand the intention of a Java JAR. Is it that a JAR should not contain dependencies, and leave it to the runtime configuration (the app container, the runtime environment, etc.) to supply it with the dependencies it needs? I would assume if this is the case, an executable JAR is an exception to the rule, yes? Or, is it the intention for Java JARs to also include their dependencies? Either way, I don't want to be forcing my users to be copying-n-pasting 25+ JARs into their Ant libs; that's just cruel. I like the way WAR files are set up, where the classpath for dependencies is defined under the classes/ directory. I guess, ultimately, I'd like my JAR structure to look like: myfirsttask.jar/ com/ --> the root package of my compiled binaries config/ --> config files, XML, XSD, etc. classes/ --> all dependencies, guice-3.0.jar, xstream-1.4.3.jar, etc. META-INF/ MANIFEST.MF I assume that in order to accomplish this (and get the runtime classpath to also look into the classes/ directory), I'll need to modify the MANIFEST.MF somehow (I know there's a manifest attribute called ClassPath, I believe?). I'm just having a tough time putting everything together, and have a looming/lingering question about the very intent of JARs to begin with. Can someone please confirm whether Oracle intends for JARs to contain their dependencies or not? And, either way, what I would have to do in the manifest (or anywhere else) to make sure that, at runtime, the classpath can find the dependencies stored under the classes/ directory? Thanks in advance!

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• Are Objective-C initializers allowed to share the same name?

  - by NattKatt

  I'm running into an odd issue in Objective-C when I have two classes using initializers of the same name, but differently-typed arguments. For example, let's say I create classes A and B: A.h: #import <Cocoa/Cocoa.h> @interface A : NSObject { } - (id)initWithNum:(float)theNum; @end A.m: #import "A.h" @implementation A - (id)initWithNum:(float)theNum { self = [super init]; if (self != nil) { NSLog(@"A: %f", theNum); } return self; } @end B.h: #import <Cocoa/Cocoa.h> @interface B : NSObject { } - (id)initWithNum:(int)theNum; @end B.m: #import "B.h" @implementation B - (id)initWithNum:(int)theNum { self = [super init]; if (self != nil) { NSLog(@"B: %d", theNum); } return self; } @end main.m: #import <Foundation/Foundation.h> #import "A.h" #import "B.h" int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; A *a = [[A alloc] initWithNum:20.0f]; B *b = [[B alloc] initWithNum:10]; [a release]; [b release]; [pool drain]; return 0; } When I run this, I get the following output: 2010-04-26 20:44:06.820 FnTest[14617:a0f] A: 20.000000 2010-04-26 20:44:06.823 FnTest[14617:a0f] B: 1 If I reverse the order of the imports so it imports B.h first, I get: 2010-04-26 20:45:03.034 FnTest[14635:a0f] A: 0.000000 2010-04-26 20:45:03.038 FnTest[14635:a0f] B: 10 For some reason, it seems like it's using the data type defined in whichever @interface gets included first for both classes. I did some stepping through the debugger and found that the isa pointer for both a and b objects ends up the same. I also found out that if I no longer make the alloc and init calls inline, both initializations seem to work properly, e.g.: A *a = [A alloc]; [a initWithNum:20.0f]; If I use this convention when I create both a and b, I get the right output and the isa pointers seem to be different for each object. Am I doing something wrong? I would have thought multiple classes could have the same initializer names, but perhaps that is not the case.

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• Memory leaks getting sub-images from video (cvGetSubRect)

  - by dnul

  Hi, i'm trying to do video windowing that is: show all frames from a video and also some sub-image from each frame. This sub-image can change size and be taken from a different position of the original frame. So , the code i've written does basically this: cvQueryFrame to get a new image from the video Create a new IplImage (img) with sub-image dimensions ( window.height,window.width) Create a new Cvmat (mat) with sub-image dimensions ( window.height,window.width) CvGetSubRect(originalImage,mat,window) seizes the sub-image transform Mat (cvMat) to img (IplImage) using cvGetImage my problem is that for each frame i create new IplImage and cvMat which take a lot of memory and when i try to free the allocated memory I get a segmentation fault or in the case of the CvMat the allocated space does not get free (valgrind keeps telling me its definetly lost space). the following code does it: int main(void){ CvCapture* capture; CvRect window; CvMat * tmp; //window size window.x=0;window.y=0;window.height=100;window.width=100; IplImage * src=NULL,*bk=NULL,* sub=NULL; capture=cvCreateFileCapture( "somevideo.wmv"); while((src=cvQueryFrame(capture))!=NULL){ cvShowImage("common",src); //get sub-image sub=cvCreateImage(cvSize(window.height,window.width),8,3); tmp =cvCreateMat(window.height, window.width,CV_8UC1); cvGetSubRect(src, tmp , window); sub=cvGetImage(tmp, sub); cvShowImage("Window",sub); //free space if(bk!=NULL) cvReleaseImage(&bk); bk=sub; cvReleaseMat(&tmp); cvWaitKey(20); //window dimensions changes window.width++; window.height++; } } cvReleaseMat(&tmp); does not seem to have any effect on the total amount of lost memory, valgrind reports the same amount of "definetly lost" memory if i comment or uncomment this line. cvReleaseImage(&bk); produces a segmentation fault. notice i'm trying to free the previous sub-frame which i'm backing up in the bk variable. If i comment this line the program runs smoothly but with lots of memory leaks I really need to get rid of memory leaks, can anyone explain me how to correct this or even better how to correctly perform image windowing? Thank you

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• Multiple layouts in rails [Newbie Q]

  - by BriteLite

  Hi. As a newb, I decided to build a "home inventory" application. I am now stuck on how to programmatically select a layout based on what type of item it is when viewing it in a browser. According to my planning, so far I should have created a few models to represent types of items I can find in my home: Furniture, Electronics and Books. class Book < ActiveRecord::Base end class Furniture < ActiveRecord::Base end class Electronic < ActiveRecord::Base end Now the Books model has things like isbn, pages, address, and category. Furniture model has things like color, price, address, and category. Electronics has things like name, voltage, address, and category. Here is where I got confused. I know the property address is going to be the same for all of them. I also know that, I will need to create multiple "layouts" for 3 different types of items to show the different properties of said items with appropriate graphics and stylesheets. But how will I go about deciding which category the item is so I can determine which layout to render. According to me, this is how I will do it: class DisplayController < ApplicationController def display @item = Params[:item] if @item.category = "electronics" render :layout => 'electronics' end end In my routes.rb map.display ':item', :controller => 'display', :action => 'display' I only seem to have one concern with this, I probably will add a lot of categories later on and think there should be a more DRY-esque way of dealing, rather than hardcoding them. I understand that I need to add into my layout html tags to display relevant information for that particular category. ----Questions---- Is this the right way to approach this type of problem. Will this approach be compatible when I decide to add a gem like *thinking_sphinx* to run search. What issues do you see with my approach and how can I make it better. I was reading something about "Polymorphic Assoc", does that apply in this case, since category exist for all items? Also, I was trying to get a routes to render a URL like "http://localhost/living-room-tv"

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