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• Segfault on copy constructor for string

  - by user2756569

  I'm getting a segfault on a line where I'm creating a c++ string with the copy constructor. I've looked at some of the similar issues, but they're all due to passing in a bad c++ string object. I'm just passing in a raw string, so I'm not sure what my issue is. I'll paste the relevant snippets of code (it's taken from several different files, so it might look a bit jumbled). The segfault occurs in the 4th line of the default constructor for the Species class. Species::Species(string _type) { program_length = 0; cout << _type << " 1\n"; cout << type << " 2\n"; type = string(_type); } Grid::Grid(int _width, int _height) { *wall = Species("wall"); *empty = Species("empty"); turn_number = 0; width = _width; height = _height; for(int a= 0; a < 100; a++) for(int b = 0; b< 100; b++) { Creature empty_creature = Creature(*empty,a,b,NORTH,this); (Grid::map)[a][b] = empty_creature; } } int main() { Grid world = Grid(8,8); } class Grid { protected: Creature map[100][100]; int width,height; int turn_number; Species *empty; Species *wall; public: Grid(); Grid(int _width, int _height); void addCreature(Species &_species, int x, int y, Direction orientation); void addWall(int x, int y); void takeTurn(); void infect(int x, int y, Direction orientation, Species &_species); void hop(int x, int y, Direction orientation); bool ifWall(int x, int y, Direction orientation); bool ifEnemy(int x, int y, Direction orientation, Species &_species); bool ifEmpty(int x, int y, Direction orientation); void print(); }; class Species { protected: int program_length; string program[100]; string type; public: species(string _type); void addInstruction(string instruction); bool isWall(); bool isEmpty(); bool isEnemy(Species _enemy); string instructionAt(int index); string getType(); };

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• Possible iphone animation timing/rendering bug?

  - by David

  Hi all, I have been working on an iphone apps for several weeks. Now I encounter an animation problem that I can't figure out how to resolve. Mayhbe you can help. Here is the details (a little long, bear with me): Basically the effect I want to achieve is, when user click a button, a loading view pops up, hiding the whole screen; and then the apps does a lot of heavy computation, which takes a few seconds. Once the computation is done, soem result views (something likes checkers on a checker board) are rendered under the loading view. Once all result views are rendered, I used animation animation to remove the loading view nand show the result views to the user. Here is what I do: when user click a button, run this code: [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:1.0]; [UIView setAnimationBeginsFromCurrentState:YES]; [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES]; [UIView setAnimationDelegate:self]; [UIView setAnimationDidStopSelector:@selector(loadingViewInserted:finished:context:)]; // use a really high index number so it will always on top [self.view insertSubview:loadingViewController.view atIndex:1000]; [UIView commitAnimations]; In the "loadingViewInserted" function, it calls another function doing the heavy computation work. Once the computation is done, a lot of result views (like checkers on a checker board) are rendered under the loading view. for(int colIndex = 1; colIndex <= result.columns; colIndex++) { for(int rowIndex = 1; rowIndex <= result.rows; rowIndex++) { ResultView *rv = [ResultView resultViewWithData:results[colIndex][rowIndex]]; [self.view addSubview:rv]; } } Once all result views are added, following animation is invoked to remove the loading view: [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:1.0]; [UIView setAnimationBeginsFromCurrentState:YES]; [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES]; [loadingViewController.view removeFromSuperview]; [UIView commitAnimations]; By doing this, most of the time (maybe 90%) it does exactly what I want. However, sometime I see some weird result: the loading view shows up first as expected, then before it disappears, some result views, which suppose to be under the loading view, suddenly appears on top of the loading view; and some of them are partial rendered. And then the loading view curled up, and everything looks normal again. The weird situation only lasts for less than a second, but already bad enough to screw up the UI. I have tried all different kinds of thing to fix this (using another thread to remove the loading view, make the loading view non-transparent), but none of them works. The only thing that makes a little better is, I hide all the result views first; after the last animation finished, in its call back, unhide all result views. But this loses the nice effect that when curling up the loading view, the results are already there. At this point, I really think this is a bug in iphone (I compile it with OS 3.0) OS. Or maybe you can point out what I have done wrong (or could do differently). (thanks for finishing this long post, :-) )

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• The best JSF coding pattern for editing JPA entities using @RequestScoped only

  - by AlanObject

  I am in a project where I will write a lot of pages like this, so I want to use the most efficient (to write) coding pattern. Background: In the past I have used CODI's @ViewAccessScoped to preserve state between requests, and more recently I have started using flash scoped objects to save state. I can't use JSF @ViewScoped because I use CDI and they don't play well together. So I want to see if I can do this with only @RequestScoped backing beans. The page is designed like this (the p namespace is Primefaces): <f:metadata> <f:viewParam name="ID" value="#{backing.id}" /> </f:metadata> .... <h1>Edit Object Page</h1> <h:form id="formObj" rendered="#{backing.accessOK}"> <p:panelGrid columns="2"> <h:outputLabel value="Field #1:"/> <p:inputText value="#{backing.record.field1}" /> (more input fields) <h:outputLabel value="Action:" /> <h:panelGroup> <p:commandButton value="Save" action="#{backing.save}" /> <p:commandButton value="Cancel" action="backing.cancel" /> </h:panelGroup> </p:panelGrid> <p:messages showDetail="true" showSummary="true" /> </h:form> If the page is requested, the method accessOK() has the ability to keep the h:form from being rendered. Instead, the p:messages is shown with whatever FacesMessage(s) the accessOK() method cares to set. The pattern for the bean backing looks like this: @Named @RequestScoped public class Backing { private long id; private SomeJPAEntity record; private Boolean accessOK; public long getId() { return id; } public void setId(long value) { id = value; } public boolean accessOK() { if (accessOK != null) return accessOK; if (getRecord() == null) { // add a FacesMessage that explains the record // does not exist return accessOK = false; // note single = } // do any other access checks, such as write permissions return accessOK = true; } public SomeJPAEntity getRecord() { if (record != null) return record; if (getId() > 0) record = // get the record from DB else record = new SomeJPAEntity(); return record; } public String execute() { if (!accessOK()) return null; // bad edit // do other integrity checks here. If fail, set FacesMessages // and return null; if (getId() > 0) // merge the record back into the data base else // persist the record } } Here is what goes wrong with this model. When the Save button is clicked, a new instance of Backing is built, and then there are a lot of calls to the getRecord() getter before the setID() setter is called. So the logic in getRecord() breaks because it cannot rely on the id property being valid when it is called. When this was a @ViewAccessScoped (or ViewScoped) backing bean, then both the id and record properties are already set when the form is processed with the commandButton. Alternatively you can save those properties in flash storage but that has its own problems I want to avoid. So is there a way to make this programming model work within the specification?

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• Iphone: controlling text with delay problem with UIWebView

  - by James B.

  Hi, I've opted to use UIWebView so I can control the layout of text I've got contained in a local html document in my bundle. I want the text to display within a UIWebView I've got contained within my view. So the text isn't the whole view, just part of it. Everything runs fine, but when the web page loads I get a blank screen for a second before the text appears. This looks really bad. can anyone give me an example of how to stop this happening? I'm assuming I have to somehow hide the web view until it has fully loaded? Could someone one tell me how to do this? At the moment I'm calling my code through the viewDidLoad like this: [myUIWebView loadRequest: [NSURLRequest requestWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle]pathForResource:@"localwebpage" ofType:@"html"] isDirectory:NO]]]; Any help is much appreciated. I've read round a few forums and not seen a good answer to this question, and it seems like it recurs a lot as an issue for beginners like myself. Thanks for taking the time to read this post! UPDATED info Thanks for your response. The suggestions below solves the problem but creates a new one for me as now when my view loads it is totally hidden until I click on my toggle switch. to understand this it's maybe most helpful if I post all my code. Before this though let me explain the setup of my view. I've got a standard view within which I've also got two web views, one on top of the other. each web view contains different text with different styling. the user flicks between views using a toggle switch, which hides/reveals the web views. I'm using the web views because I want to control the style/layout of the text. Below is my full .m code, I can't figure out where it's going wrong. My web views are called oxford & harvard I'm sure its something to do with how/when I'm hiding/revealing views. I've played around with this but can't seem to get it right. Maybe my approach is wrong. A bit of advice ironing this out would be really appreciated: @implementation ReferenceViewController @synthesize oxford; @synthesize harvard; // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; [oxford loadRequest: [NSURLRequest requestWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle]pathForResource:@"Oxford" ofType:@"html"] isDirectory:NO]]]; [harvard loadRequest: [NSURLRequest requestWithURL:[NSURL fileURLWithPath:[[NSBundle mainBundle]pathForResource:@"Harvard" ofType:@"html"] isDirectory:NO]]]; [oxford setHidden:YES]; [harvard setHidden:YES]; } - (void)webViewDidFinishLoad:(UIWebView *)webView { if([webView hidden]) { [oxford setHidden:NO]; [harvard setHidden:NO]; } } //Toggle controls for toggle switch in UIView to swap between webviews - (IBAction)toggleControls:(id)sender { if ([sender selectedSegmentIndex] == kSwitchesSegmentIndex) { oxford.hidden = NO; harvard.hidden = YES; } else { oxford.hidden = YES; harvard.hidden = NO; } } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { [super viewDidUnload]; // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [super dealloc]; [oxford release]; [harvard release]; } @end

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• Event handle in drop-down menu.

  - by QLiu

  Hello fellows, I am trying to develop a dynamic drop down menu by a customized widget style The custom widget has two main features: Read user's location cookies variable to set the proper contact phone number in the CP pages When users select on the drop down menu, it triggers onChange event, it re-select the contact phone number based on users' selections, but it won't reset the location cookies. My widgets conatins two files: Controller.php: Simply one, it uses to handle get cookies variables class serial extends Widget { function __construct() { parent::__construct(); } function generateWidgetInformation() { $this->info['notes'] = "Serial Number search Box"; } function getData() { //Get cookies code will go here, and pass to view.php $this->data['locale'] = 'gb';// for test purpose now } } view.php is about Presentation layer contains HTML, which get the data from my controller <div style="border: 1px solid black; display: block;" id="<?=$this->instanceID;?>"></div> <script>locale2contact('<?=$this->data['locale']?>', '<?=$this->instanceID;?>');</script> And then the Javascript function, call locale2contact var element_id =''; //Define Global Variables, //Receive the cookies locale, and instance id from view.php function locale2contact(locale, instance_id) { var details = ''; this.element_id=instance_id; //assing the instance id into global variable // alert(instance_id); //Check whether we got the instance id from view files if (locale == 'gb') details = 'UK Contact Details<br>' + build_dropdown(locale); else if (locale == 'fr') details = 'French Contact Details<br>'+build_dropdown(locale); else if (locale == 'be') details = 'Belgian Contact Details<br>'+ build_dropdown(locale); else details = 'Unknown Contact Detail'; writeContactInfo(details); } //Build the drop down menu with pre-selected option by using cookies. function build_dropdown(locale) { var dropdown = '<select onChange=changeContactInfo(this.options[selectedIndex].text)>'; dropdown += '<option' + (locale == 'gb' ? ' selected' : '') + '>UK</option>'; dropdown += '<option' + (locale == 'be' ? ' selected' : '') + '>Belgium</option>'; dropdown += '</select>'; return dropdown; } // Not smart way in here, once the people select the drop down box, it reselect the drop down menu and reset the contact info function changeContactInfo(selected) { var details =''; //alert(this.element_id); //alert(locale); if (selected == 'UK') details = 'UK Contact Details<br>' + build_dropdown2(selected); else if (selected == 'fr') details = 'French Contact Details<br>'+ build_dropdown2(selected); else if (selected == 'Belgium') details = 'Belgian Contact Details<br>'+ build_dropdown2(selected); else details = 'Unknown Contact Detail'; writeContactInfo(details); } //Build the drop down menu function build_dropdown2(selected) { var dropdown = '<select onChange=changeContactInfo(this.options[selectedIndex].text)>'; dropdown += '<option' + (selected == 'UK' ? ' selected' : '') + '>UK</option>'; dropdown += '<option' + (selected == 'Belgium' ? ' selected' : '') + '>Belgium</option>'; dropdown += '</select>'; return dropdown; } //Back to view function writeContactInfo(details) { document.getElementById(this.element_id).innerHTML = details; //update the instance field in view } Javascript function is not efficient. As you see, I got two similar duplicate functions to handle events. Users go to the page, the widget read the cookies variable to display contact info (locale2contact)and preselect the drop-down menu (function build_dropdown) If users select the drop down menu, the displya contact info change (function changeContactInfo), and then I need to rebuild the drop down menu with user previously selection (function build_dropdown2). I am looking for best practices for adding this functionality to RightNow widget. Thank you. I really do not like the way i am doing now. It works; but the code looks bad.

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• Clearcase - selective merge.

  - by Keshav

  Hi, I have a peculiar Clearcase doubt. I cannot fully describe why I'm doing such a confusing architecture, but I need to do it (thanks to the mistake done by someone long back). Ok, here's a bit of detail: B1 is a contaminated branch where both my group's changes and another group's changes got mixed together so badly that there is no way of finding which code is whose). So the solution proposed is to create a new branch called B2 (at the same level as B1) and put all the unmodified code of the other group on it (The way to do that would be to merge B1 with B2 and then go about removing all changes from it till it becomes original). Then create a CR branch on B1 and keep only my group's newly added files or modified files on that branch. Finally create an integration branch out of B2 and merge the changes from CR branch of B1 to integration branch of B2. So here is what I did: (The use case is where I have dir D where file a, b and c are there. My group ended up modifying file a while b and c are not modified at all). There is a branch B1 on which there are files a, b and c. There is another branch B2. A merge is done from B1 to B2. Now B2 also has a, b and c. At this point both branch B1 and B2 are same. Now I delete file a from branch B2 (rmname). Now B2 has b and c only. I put a label to this branch called Label1. This makes the code with label Label1 as the unmodified code from other group. Now I create a sub branch called CR1 from B1 and delete all the files that are there in B2 branch (i.e b and c) such that it contains only the modified code from original code on it. In my case it is file a. At this point branch B2 with label Label1 has files b and c (those are unmodified code) and branch CR1 coming off B1 has only a (that is modified by us). Now I create another branch called integration branch that comes off B2 Label1. And then I do a merge of CR branch on to that expecting that it will have all three files a, b and c for me. All I'd need to do is to do a version tree view and see who modified what. But the problem I face is that since I had done a rmname of file a on branch B2 earlier to putting Label. The merge does not really take the file a from CR branch. How to I get around that problem. I want to selectively merge. Is it possible? sorry if it is a bad design. I'm not really conversant with Clear case and have limited options and time to clear some one else's mess.

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• Is it possible to reference a linkbotton outside an update panel as the update trigger?

  - by Selase

  I have a page based on a master page and as such i can only see the content place holders i used in the master page showing up in the aspx pages based on the master page. the source code shown below: <%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="CaseAdmin.aspx.cs" Inherits="Prototype4.CaseAdmin" %> <%@PreviousPageType VirtualPath="~/Account/Login.aspx"%> <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> </asp:Content> <asp:Content ID="CaseRightNews" ContentPlaceHolderID="RightNewsItem" runat="server"> </asp:Content> <asp:Content ID="CaseLeftNav" ContentPlaceHolderID="LeftNavigation" runat="server"> <div style="margin-top:20px; margin-bottom:20px;"> <p class="actionButton"> <asp:LinkButton ID="OpenCaseLinkButton" runat="server" onclick="OpenCaseLinkButton_Click">Open Case</asp:LinkButton> </p> <p class="actionButton"><asp:LinkButton ID="RegisterExhibitLinkButton" runat="server" onclick="RegisterExhibitLinkButton_Click">Register Exhibit</asp:LinkButton> </p> </div> </asp:Content> <asp:Content ID="CaseMainContnt" ContentPlaceHolderID="MainContent" runat="server"> <asp:ScriptManager ID="ScriptManager" runat="server" /> <asp:UpdatePanel ID="CaseMainCntntUpdatePanel" UpdateMode="Conditional" runat="server"> <Triggers> <asp:AsyncPostBackTrigger ControlID="" eventname="Click"/> </Triggers> <ContentTemplate> <%--Some text here to inform user to click on the open case botton to display open case form--%> </ContentTemplate> </asp:UpdatePanel> <asp:UpdatePanel runat="server" id="UpdatePanel1" updatemode="Conditional"> <Triggers> <asp:AsyncPostBackTrigger ControlID="" eventname="Click"/> </Triggers> <ContentTemplate> <%--some text here to inform users to click on the add exhibit botton to display add exhibit form--%> </ContentTemplate> </asp:UpdatePanel> </asp:Content> the section of the entire page i wish to change upon update is the (this is the main content of the page). for this reason i placed the updatepanel inside the content place holder since it cant be sitting outside and not wrapped in a content place holder. However, the buttons that i wish to apply the trigger that fires the update to, are in another content place holder(). How can i possibly get those buttons to act as the trigger while changing only what appears in the main content area. Plus, i tried getting the updatepanel to work just so i could see if it does the update well but it turned out really bad. i added some linkbottons in the content template area and used them as the triggers for testing reasons. i tested and the changes took over the entire page in contrast to just appearing in the content area. I actually just wanted to load a form that is created in another asp. page into the main content area... I seriously need help with this... Every little help, detail and information is dearly appreciated... thanks so much in advance

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• Game logic dynamically extendable architecture implementation patterns

  - by Vlad

  When coding games there are a lot of cases when you need to inject your logic into existing class dynamically and without making unnecessary dependencies. For an example I have a Rabbit which can be affected by freeze ability so it can't jump. It could be implemented like this: class Rabbit { public bool CanJump { get; set; } void Jump() { if (!CanJump) return; ... } } But If I have more than one ability that can prevent it from jumping? I can't just set one property because some circumstances can be activated simultanously. Another solution? class Rabbit { public bool Frozen { get; set; } public bool InWater { get; set; } bool CanJump { get { return !Frozen && !InWater; } } } Bad. The Rabbit class can't know all the circumstances it can run into. Who knows what else will game designer want to add: may be an ability that changes gravity on an area? May be make a stack of bool values for CanJump property? No, because abilities can be deactivated not in that order in which they were activated. I need a way to seperate ability logic that prevent the Rabbit from jumping from the Rabbit itself. One possible solution for this is making special checking event: class Rabbit { class CheckJumpEventArgs : EventArgs { public bool Veto { get; set; } } public event EventHandler<CheckJumpEvent> OnCheckJump; void Jump() { var args = new CheckJumpEventArgs(); if (OnCheckJump != null) OnCheckJump(this, args); if (!args.Veto) return; ... } } But it's a lot of code! A real Rabbit class would have a lot of properties like this (health and speed attributes, etc). I'm thinking of borrowing something from MVVM pattern where you have all the properties and methods of an object implemented in a way where they can be easily extended from outside. Then I want to use it like this: class FreezeAbility { void ActivateAbility() { _rabbit.CanJump.Push(ReturnFalse); } void DeactivateAbility() { _rabbit.CanJump.Remove(ReturnFalse); } // should be implemented as instance member // so it can be "unsubscribed" bool ReturnFalse(bool previousValue) { return false; } } Is this approach good? What also should I consider? What are other suitable options and patterns? Any ready to use solutions? UPDATE The question is not about how to add different behaviors to an object dynamically but how its (or its behavior) implementation can be extended with external logic. I don't need to add a different behavior but I need a way to modify an exitsing one and I also need a possibiliity to undo changes.

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• ZF: Form array field - how to display values in the view correctly

  - by Wojciech Fracz

  Let's say I have a Zend_Form form that has a few text fields, e.g: $form = new Zend_Form(); $form->addElement('text', 'name', array( 'required' => true, 'isArray' => true, 'filters' => array( /* ... */ ), 'validators' => array( /* ... */ ), )); $form->addElement('text', 'surname', array( 'required' => true, 'isArray' => true, 'filters' => array( /* ... */ ), 'validators' => array( /* ... */ ), )); After rendering it I have following HTML markup (simplified): <div id="people"> <div class="person"> <input type="text" name="name[]" /> <input type="text" name="surname[]" /> </div> </div> Now I want to have the ability to add as many people as I want. I create a "+" button that in Javascript appends next div.person to the container. Before I submit the form, I have for example 5 names and 5 surnames, posted to the server as arrays. Everything is fine unless somebody puts the value in the field that does not validate. Then the whole form validation fails and when I want to display the form again (with errors) I see the PHP Warning: htmlspecialchars() expects parameter 1 to be string, array given Which is more or less described in ticket: http://framework.zend.com/issues/browse/ZF-8112 However, I came up with a not-very-elegant solution. What I wanted to achieve: have all fields and values rendered again in the view have error messages only next to the fields that contained bad values Here is my solution (view script): <div id="people"> <?php $names = $form->name->getValue(); // will have an array here if the form were submitted $surnames= $form->surname->getValue(); // only if the form were submitted we need to validate fields' values // and display errors next to them; otherwise when user enter the page // and render the form for the first time - he would see Required validator // errors $needsValidation = is_array($names) || is_array($surnames); // print empty fields when the form is displayed the first time if(!is_array($names))$names= array(''); if(!is_array($surnames))$surnames= array(''); // display all fields! foreach($names as $index => $name): $surname = $surnames[$index]; // validate value if needed if($needsValidation){ $form->name->isValid($name); $form->surname->isValid($surname); } ?> <div class="person"> <?=$form->name->setValue($name); // display field with error if did not pass the validation ?> <?=$form->surname->setValue($surname);?> </div> <?php endforeach; ?> </div> The code work, but I want to know if there is an appropriate, more comfortable way to do this? I often hit this problem when there is a need for a more dynamic - multivalue forms and have not find better solution for a long time.

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• ANT: ways to include libraries and license issues

  - by Eric Tobias

  I have been trying to use Ant to compile and ready a project for distribution. I have encountered several problems along the way that I have been finally able to solve but the solution leaves me very unsatisfied. First, let me explain the set-up of the project and its dependencies. I have a project, lets call it Primary which depends on a couple of libraries such as the fantastic Guava. It also depends on another project of mine, lets call it Secondary. The Secondary project also features some dependencies, for example, JDOM2. I have referenced the Jar I build with Ant in Primary. Let me give you the interesting bits of the build.xml so you can get a picture of what I am doing: <project name="Primary" default="all" basedir="."> <property name='build' location='dist' /> <property name='application.version' value='1.0'/> <property name='application.name' value='Primary'/> <property name='distribution' value='${application.name}-${application.version}'/> <path id='compile.classpath'> <fileset dir='libs'> <include name='*.jar'/> </fileset> </path> <target name='compile' description='Compile source files.'> <javac includeantruntime="false" srcdir="src" destdir="bin"> <classpath refid='compile.classpath'/> </javac> <target> <target name='jar' description='Create a jar file for distribution.' depends="compile"> <jar destfile='${build}/${distribution}.jar'> <fileset dir="bin"/> <zipgroupfileset dir="libs" includes="*.jar"/> </jar> </target> The Secodnary project's build.xml is nearly identical except that it features a manifest as it needs to run: <target name='jar' description='Create a jar file for distribution.' depends="compile"> <jar destfile='${dist}/${distribution}.jar' basedir="${build}" > <fileset dir="${build}"/> <zipgroupfileset dir="libs" includes="*.jar"/> <manifest> <attribute name="Main-Class" value="lu.tudor.ssi.kiss.climate.ClimateChange"/> </manifest> </jar> </target> After I got it working, trying for many hours to not include that dependencies as class files but as Jars, I don't have the time or insight to go back and try to figure out what I did wrong. Furthermore, I believe that including these libraries as class files is bad practice as it could give rise to licensing issues while not packaging them and merely including them in a directory along the build Jar would most probably not (And if it would you could choose not to distribute them yourself). I think my inability to correctly assemble the class path, I always received NoClassDefFoundError for classes or libraries in the Primary project when launching Second's Jar, is that I am not very experienced with Ant. Would I require to specify a class path for both projects? Specifying the class path as . should have allowed me to simply add all dependencies to the same folder as Secondary's Jar, should it not?

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• What am I doing wrong?, linking in C++

  - by Facon

  I'm trying to code a simple base64 encoder/decoder (to test my programming skill). I can compile it, but it doesn't link, I've this message error: C:\Documents and Settings\Facon\Escritoriog++ base64.o main.o -o prueba.exe main.o:main.cpp:(.text+0x24a): undefined reference to `Base64Encode(std::vector const&)' collect2: ld returned 1 exit status Compiler & Linker: Mingw32 3.4.5 SO: Windows XP This is my source code: base64.h: #ifndef BASE64_H #define BASE64_H #include <iostream> #include <vector> typedef unsigned char byte; std::string Base64Encode(const std::vector<byte> &array); std::vector<byte> Base64Decode(const std::string &array); #endif base64.cpp: #include "base64.h" std::string Base64Encode(std::vector<byte> &array) { const char *base64_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; const unsigned int size = array.size(); std::string output; for (unsigned int i = 0; (i < size); i++) { if ((size - i) > 3) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x03) << 4) | ((array[i] & 0xF0) >> 4)])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x0F) << 2) | ((array[i] & 0xC0) >> 4)])); output.push_back(static_cast<char>(base64_table[array[i] & 0x3F])); } else if ((size - i) == 3) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[((array[i++] & 0x03) << 4) | ((array[i] & 0xF0) >> 4)])); output.push_back(static_cast<char>(base64_table[(array[i] & 0x0F) << 2])); output.push_back(static_cast<char>('=')); } else if ((size - i) == 2) { output.push_back(static_cast<char>(base64_table[array[i] >> 2])); output.push_back(static_cast<char>(base64_table[(array[i] & 0x03) << 4])); output.push_back('='); output.push_back('='); } } return output; } std::vector<byte> Base64Decode(const std::string &array) // TODO { const char *base64_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; } main.cpp: #include <iostream> #include <vector> #include "base64.h" using namespace std; int main(int argc, char *argv[]) { const char* prueba = "sure."; vector<byte> texto; string codificado; for (unsigned int i = 0; (prueba[i] != 0); i++) { texto.push_back(prueba[i]); } codificado = Base64Encode(texto); cout << codificado; return 0; } PD: Sorry for my bad knowledge of English :P

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• Question about unions and heap allocated memory

  - by Dennis Miller

  I was trying to use a union to so I could update the fields in one thread and then read allfields in another thread. In the actual system, I have mutexes to make sure everything is safe. The problem is with fieldB, before I had to change it fieldB was declared like field A and C. However, due to a third party driver, fieldB must be alligned with page boundary. When I changed field B to be allocated with valloc, I run into problems. Questions: 1) Is there a way to statically declare fieldB alligned on page boundary. Basically do the same thing as valloc, but on the stack? 2) Is it possible to do a union when field B, or any field is being allocated on the heap?. Not sure if that is even legal. Here's a simple Test program I was experimenting with. This doesn't work unless you declare fieldB like field A and C, and make the obvious changes in the public methods. #include <iostream> #include <stdlib.h> #include <string.h> #include <stdio.h> class Test { public: Test(void) { // field B must be alligned to page boundary // Is there a way to do this on the stack??? this->field.fieldB = (unsigned char*) valloc(10); }; //I know this is bad, this class is being treated like //a global structure. Its self contained in another class. unsigned char* PointerToFieldA(void) { return &this->field.fieldA[0]; } unsigned char* PointerToFieldB(void) { return this->field.fieldB; } unsigned char* PointerToFieldC(void) { return &this->field.fieldC[0]; } unsigned char* PointerToAllFields(void) { return &this->allFields[0]; } private: // Is this union possible with field B being // allocated on the heap? union { struct { unsigned char fieldA[10]; //This field has to be alligned to page boundary //Is there way to be declared on the stack unsigned char* fieldB; unsigned char fieldC[10]; } field; unsigned char allFields[30]; }; }; int main() { Test test; strncpy((char*) test.PointerToFieldA(), "0123456789", 10); strncpy((char*) test.PointerToFieldB(), "1234567890", 10); strncpy((char*) test.PointerToFieldC(), "2345678901", 10); char dummy[11]; dummy[10] = '\0'; strncpy(dummy, (char*) test.PointerToFieldA(), 10); printf("%s\n", dummy); strncpy(dummy, (char*) test.PointerToFieldB(), 10); printf("%s\n", dummy); strncpy(dummy, (char*) test.PointerToFieldC(), 10); printf("%s\n", dummy); char allFields[31]; allFields[30] = '\0'; strncpy(allFields, (char*) test.PointerToAllFields(), 30); printf("%s\n", allFields); return 0; }

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• What is the best practice when coding math class/functions ?

  - by Isaac Clarke

  Introductory note : I voluntarily chose a wide subject. You know that quote about learning a cat to fish, that's it. I don't need an answer to my question, I need an explanation and advice. I know you guys are good at this ;) Hi guys, I'm currently implementing some algorithms into an existing program. Long story short, I created a new class, "Adder". An Adder is a member of another class representing the physical object actually doing the calculus , which calls adder.calc() with its parameters (merely a list of objects to do the maths on). To do these maths, I need some parameters, which do not exist outside of the class (but can be set, see below). They're neither config parameters nor members of other classes. These parameters are D1 and D2, distances, and three arrays of fixed size : alpha, beta, delta. I know some of you are more comfortable reading code than reading text so here you go : class Adder { public: Adder(); virtual Adder::~Adder(); void set( float d1, float d2 ); void set( float d1, float d2, int alpha[N_MAX], int beta[N_MAX], int delta[N_MAX] ); // Snipped prototypes float calc( List& ... ); // ... inline float get_d1() { return d1_ ;}; inline float get_d2() { return d2_ ;}; private: float d1_; float d2_; int alpha_[N_MAX]; // A #define N_MAX is done elsewhere int beta_[N_MAX]; int delta_[N_MAX]; }; Since this object is used as a member of another class, it is declared in a *.h : private: Adder adder_; By doing that, I couldn't initialize the arrays (alpha/beta/delta) directly in the constructor ( int T[3] = { 1, 2, 3 }; ), without having to iterate throughout the three arrays. I thought of putting them in static const, but I don't think that's the proper way of solving such problems. My second guess was to use the constructor to initialize the arrays Adder::Adder() { int alpha[N_MAX] = { 0, -60, -120, 180, 120, 60 }; int beta[N_MAX] = { 0, 0, 0, 0, 0, 0 }; int delta[N_MAX] = { 0, 0, 180, 180, 180, 0 }; set( 2.5, 0, alpha, beta, delta ); } void Adder::set( float d1, float d2 ) { if (d1 > 0) d1_ = d1; if (d2 > 0) d2_ = d2; } void Adder::set( float d1, float d2, int alpha[N_MAX], int beta[N_MAX], int delta[N_MAX] ) { set( d1, d2 ); for (int i = 0; i < N_MAX; ++i) { alpha_[i] = alpha[i]; beta_[i] = beta[i]; delta_[i] = delta[i]; } } My question is : Would it be better to use another function - init() - which would initialize arrays ? Or is there a better way of doing that ? My bonus question is : Did you see some mistakes or bad practice along the way ?

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• PHP - Code Sample - Polymorphism Implementation - How to allow for expansion?

  - by darga33

  I've read numerous SO posts about Polymorphism, and also the other really good one at http://net.tutsplus.com/tutorials/php/understanding-and-applying-polymorphism-in-php/ Good stuff!!! I'm trying to figure out how a seasoned PHP developer that follows all the best practices would accomplish the following. Please be as specific and detailed as possible. I'm sure your answer is going to help a lot of people!!! :-) While learning Polymorphism, I came across a little stumbling block. Inside of the PDFFormatter class, I had to use (instanceof) in order to figure out if some code should be included in the returned data. I am trying to be able to pass in two different kinds of profiles to the formatter. (needs to be able to handle multiple kinds of formatters but display the data specific to the Profile class that is being passed to it). It doesn't look bad now, but imagine 10 more kinds of Profiles!! How would you do this? The best answer would also include the changes you would make. Thanks sooooooo much in advance!!!!! Please PHP only! Thx!!! File 1. FormatterInterface.php interface FormatterInterface { public function format(Profile $Profile); } File 2. PDFFormatter.php class PDFFormatter implements FormatterInterface { public function format(Profile $Profile) { $format = "PDF Format<br /><br />"; $format .= "This is a profile formatted as a PDF.<br />"; $format .= 'Name: ' . $Profile->name . '<br />'; if ($Profile instanceof StudentProfile) { $format .= "Graduation Date: " . $Profile->graduationDate . "<br />"; } $format .= "<br />End of PDF file"; return $format; } } File 3. Profile.php class Profile { public $name; public function __construct($name) { $this->name = $name; } public function format(FormatterInterface $Formatter) { return $Formatter->format($this); } } File 4. StudentProfile.php class StudentProfile extends Profile { public $graduationDate; public function __construct($name, $graduationDate) { $this->name = $name; $this->graduationDate = $graduationDate; } } File 5. index.php //Assuming all files are included...... $StudentProfile = new StudentProfile('Michael Conner', 55, 'Unknown, FL', 'Graduate', '1975', 'Business Management'); $Profile = new Profile('Brandy Smith', 44, 'Houston, TX'); $PDFFormatter = new PDFFormatter(); echo '<hr />'; echo $StudentProfile->format($PDFFormatter); echo '<hr />'; echo $Profile->format($PDFFormatter);

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• Using Dynamic Proxies to centralize JPA code

  - by Daziplqa

  Hi All, Actually, This is not a question but really I need your opinions in a matter... I put his post here because I know you always active, so please don't consider this a bad question and share me your opinions. I've used Java dynamic proxies to Centralize The code of JPA that I used in a standalone mode, and Here's the dynamic proxy code: package com.forat.service; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; import java.lang.reflect.Proxy; import java.util.logging.Level; import java.util.logging.Logger; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.EntityTransaction; import javax.persistence.Persistence; import com.forat.service.exceptions.DAOException; /** * Example of usage : * <pre> * OnlineFromService onfromService = * (OnlineFromService) DAOProxy.newInstance(new OnlineFormServiceImpl()); * try { * Student s = new Student(); * s.setName("Mohammed"); * s.setNationalNumber("123456"); * onfromService.addStudent(s); * }catch (Exception ex) { * System.out.println(ex.getMessage()); * } *</pre> * @author mohammed hewedy * */ public class DAOProxy implements InvocationHandler{ private Object object; private Logger logger = Logger.getLogger(this.getClass().getSimpleName()); private DAOProxy(Object object) { this.object = object; } public static Object newInstance(Object object) { return Proxy.newProxyInstance(object.getClass().getClassLoader(), object.getClass().getInterfaces(), new DAOProxy(object)); } @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { EntityManagerFactory emf = null; EntityManager em = null; EntityTransaction et = null; Object result = null; try { emf = Persistence.createEntityManagerFactory(Constants.UNIT_NAME); em = emf.createEntityManager();; Method entityManagerSetter = object.getClass(). getDeclaredMethod(Constants.ENTITY_MANAGER_SETTER_METHOD, EntityManager.class); entityManagerSetter.invoke(object, em); et = em.getTransaction(); et.begin(); result = method.invoke(object, args); et.commit(); return result; }catch (Exception ex) { et.rollback(); Throwable cause = ex.getCause(); logger.log(Level.SEVERE, cause.getMessage()); if (cause instanceof DAOException) throw new DAOException(cause.getMessage(), cause); else throw new RuntimeException(cause.getMessage(), cause); }finally { em.close(); emf.close(); } } } And here's the link that contains more info (http://m-hewedy.blogspot.com/2010/04/using-dynamic-proxies-to-centralize-jpa.html) (plz don't consider this as adds, as I can copy and past the entire topic here if you want that) So, Please give me your opinions. Thanks.

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• SSRS 2008 printing single page renders different for print

  - by user270437

  I have a problem with SSRS 2008 reports rendering differently on the reporting server than the way it renders when you print the report. I’m trying to figure out to print a single page and have the print show that same records as I see on the report on the screen. As a test, I created a simple report with no headers or footers and just added a Tablix table to display the records (no groupings). My data set for this test displays 2 ¼ pages of records when I deploy it to our reporting services server and run it. If I click the print Icon and preview the report is 2 ¾ pages. I haven’t found anything searching on this so it makes me think it is something simple I’m missing. A basically want the report to render the same records on each page in Report Manager as it does when it prints, how do I accomplish this? (In response to answer posted by Chris)…If that is the case then it is disappointing. Customers are accustomed to WYSIWYG and will have a hard time understanding that, I imagine we will be getting a lot of support calls. This still leaves an issue. I tried using print preview and could not find any way to single out a page. If I select a page up front to print, or preview it renders different so I get different records. And if I preview the entire document, I can only print the entire document. You mentioned the Excel render; we have customers that will want that also. The problem I have found with Excel exports is that even a basic report winds up merging some cells and that messes up sorting. I’m going to try your tip about grouping to see if I can get a clean export to a page. It would have been nice if they would have created a property for certain controls like the tablix table called “ExcelSheet”. Then all you would have to do is give it a name and it would create a new sheet for each control with a name, the name becoming the sheet title. Thanks for the information you supplied it is very useful as I’m new to SSRS. If you know how I can Preview in print render and select individual pages to print from the render let me know. Update 02/19/2010 After testing this more I now realize it is just a bad design of Report managers print driver or a limitation because it is server based. The options work differently than Windows apps drivers, But I did find a work around. Here is the test I performed comparing Excel to Report Manager. I bring up a report that will render more than 1 page when printed. I then export to Excel, in Excel I select print preview. I can navigate the pages in preview and then select a single page like page 3. I can then print just page 3 without leaving print preview and it prints just like it rendered. I cannot do this using print in report manager. If I select print preview in report manager then try to print while in preview it always prints the entire document. However if I close out of print preview, I can then select page 3 and print it as rendered. It is just one additional step once you know what to do, but it took some time to figure it out.

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• Java Thread execution on same data

  - by AR89

  first of all here is the code, you can just copy an paste import java.util.ArrayList; public class RepetionCounter implements Runnable{ private int x; private int y; private int[][] matrix; private int xCounter; private int yCounter; private ArrayList<Thread> threadArray; private int rowIndex; private boolean[] countCompleted; public RepetionCounter(int x, int y, int [][]matrix) { this.x = x; this.y = y; this.matrix = matrix; this.threadArray = new ArrayList<Thread>(matrix.length); this.rowIndex = 0; for(int i = 0; i < matrix.length; i++){ threadArray.add(new Thread(this)); } countCompleted = new boolean[matrix.length]; } public void start(){ for (int i = 0; i < threadArray.size(); i++){ threadArray.get(i).start(); this.rowIndex++; } } public void count(int rowIndex) { for(int i = 0; i < matrix[rowIndex].length; i++){ if (matrix[rowIndex][i] == x){ this.xCounter++; } else if (matrix[rowIndex][i] == y){ this.yCounter++; } } } @Override public void run() { count(this.rowIndex); countCompleted[this.rowIndex] = true; } public int getxCounter() { return xCounter; } public void setxCounter(int xCounter) { this.xCounter = xCounter; } public int getyCounter() { return yCounter; } public void setyCounter(int yCounter) { this.yCounter = yCounter; } public boolean[] getCountCompleted() { return countCompleted; } public void setCountCompleted(boolean[] countCompleted) { this.countCompleted = countCompleted; } public static void main(String args[]){ int[][] matrix = {{0,2,1}, {2,3,4}, {3,2,0}}; RepetionCounter rc = new RepetionCounter(0, 2, matrix); rc.start(); boolean ready = false; while(!ready){ for(int i = 0; i < matrix.length; i++){ if (rc.getCountCompleted()[i]){ ready = true; } else { ready = false; } } } if (rc.getxCounter() > rc.getyCounter()){ System.out.println("Thre are more x than y"); } else {System.out.println("There are:"+rc.getxCounter()+" x and:"+rc.getyCounter()+" y"); } } } What I want this code to do: I give to the object a matrix and tow numbers, and I want to know how much times these two numbers occurs in the matrix. I create as many thread as the number of rows of the matrix (that' why there is that ArrayList), so in this object I have k threads (supposing k is the number of rows), each of them count the occurrences of the two numbers. The problem is: if I run it for the first time everything work, but if I try to execute it another time I get and IndexOutOfBoundException, or a bad count of the occurrences, the odd thing is that if I get the error, and modify the code, after that it will works again just for once. Can you explain to me why is this happening?

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• Basic C question, concerning memory allocation and value assignment

  - by VHristov

  Hi there, I have recently started working on my master thesis in C that I haven't used in quite a long time. Being used to Java, I'm now facing all kinds of problems all the time. I hope someone can help me with the following one, since I've been struggling with it for the past two days. So I have a really basic model of a database: tables, tuples, attributes and I'm trying to load some data into this structure. Following are the definitions: typedef struct attribute { int type; char * name; void * value; } attribute; typedef struct tuple { int tuple_id; int attribute_count; attribute * attributes; } tuple; typedef struct table { char * name; int row_count; tuple * tuples; } table; Data is coming from a file with inserts (generated for the Wisconsin benchmark), which I'm parsing. I have only integer or string values. A sample row would look like: insert into table values (9205, 541, 1, 1, 5, 5, 5, 5, 0, 1, 9205, 10, 11, 'HHHHHHH', 'HHHHHHH', 'HHHHHHH'); I've "managed" to load and parse the data and also to assign it. However, the assignment bit is buggy, since all values point to the same memory location, i.e. all rows look identical after I've loaded the data. Here is what I do: char value[10]; // assuming no value is longer than 10 chars int i, j, k; table * data = (table*) malloc(sizeof(data)); data->name = "table"; data->row_count = number_of_lines; data->tuples = (tuple*) malloc(number_of_lines*sizeof(tuple)); tuple* current_tuple; for(i=0; i<number_of_lines; i++) { current_tuple = &data->tuples[i]; current_tuple->tuple_id = i; current_tuple->attribute_count = 16; // static in our system current_tuple->attributes = (attribute*) malloc(16*sizeof(attribute)); for(k = 0; k < 16; k++) { current_tuple->attributes[k].name = attribute_names[k]; // for int values: current_tuple->attributes[k].type = DB_ATT_TYPE_INT; // write data into value-field int v = atoi(value); current_tuple->attributes[k].value = &v; // for string values: current_tuple->attributes[k].type = DB_ATT_TYPE_STRING; current_tuple->attributes[k].value = value; } // ... } While I am perfectly aware, why this is not working, I can't figure out how to get it working. I've tried following things, none of which worked: memcpy(current_tuple->attributes[k].value, &v, sizeof(int)); This results in a bad access error. Same for the following code (since I'm not quite sure which one would be the correct usage): memcpy(current_tuple->attributes[k].value, &v, 1); Not even sure if memcpy is what I need here... Also I've tried allocating memory, by doing something like: current_tuple->attributes[k].value = (int *) malloc(sizeof(int)); only to get "malloc: * error for object 0x100108e98: incorrect checksum for freed object - object was probably modified after being freed." As far as I understand this error, memory has already been allocated for this object, but I don't see where this happened. Doesn't the malloc(sizeof(attribute)) only allocate the memory needed to store an integer and two pointers (i.e. not the memory those pointers point to)? Any help would be greatly appreciated! Regards, Vassil

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• Break in Class Module vs. Break on Unhandled Errors (VB6 Error Trapping, Options Setting in IDE)

  - by Erx_VB.NExT.Coder

  Basically, I'm trying to understand the difference between the "Break in Class Module" and "Break on Unhandled Errors" that appear in the Visual Basic 6.0 IDE under the following path: Tools --> Options --> General --> Error Trapping The three options appear to be: Break on All Errors Break in Class Module Break on Unhandled Errors Now, apparently, according to MSDN, the second option (Break in Class Module) really just means "Break on Unhandled Errors in Class Modules". Also, this option appears to be set by default (ie: I think its set to this out of the box). What I am trying to figure out is, if I have the second option selected, do I get the third option (Break on Unhandled Errors) for free? In that, does it come included by default for all scenarios outside of the Class Module spectrum? To advise, I don't have any Class Modules in my currently active project. I have .bas modules though. Also, is it possible that by Class Mdules they may be referring to normal .bas Modules as well? (this is my second sub-question). Basically, I just want the setting to ensure there won't be any surprises once the exe is released. I want as many errors to display as possible while I am developing, and non to be displayed when in release mode. Normally, I have two types of On Error Resume Next on my forms where there isn't explicit error handling, they are as follows: On Error Resume Next ' REQUIRED On Error Resume Next ' NOT REQUIRED The required ones are things like, checking to see if an array has any length, if a call to its UBound errors out, that means it has no length, if it returns a value 0 or more, then it does have length (and therefore, exists). These types of Error Statements need to remain active even while I am developing. However, the NOT REQUIRED ones shouldn't remain active while I am developing, so I have them all commented out to ensure that I catch all the errors that exist. Once I am ready to release the exe, I do a CTRL+H to find all occurrences of: 'On Error Resume Next ' NOT REQUIRED (You may have noticed they are commented out)... And replace them with: On Error Resume Next ' NOT REQUIRED ... The uncommented version, so that in release mode, if there are any leftover errors, they do not show to users. For more on the description by MSDN on the three options (which I've read twice and still don't find adequate) you can visit the following link: http://webcache.googleusercontent.com/search?q=cache:yUQZZK2n2IYJ:support.microsoft.com/kb/129876&hl=en&lr=lang_en%7Clang_tr&gl=au&tbs=lr:lang_1en%7Clang_1tr&prmd=imvns&strip=1 I’m also interested in hearing your thoughts if you feel like volunteering them (and this would be my tentative/totally optional third sub-question, that being, your thoughts on fall-back error handling techniques). Just to summarize, the first two questions were, do we get option 3 included in all non-class scenarios if we choose option 2? And, is it possible that when they use the term "Class Module" they may be referring to .bas Modules as well? (Since a .bad Module is really just a class module that is pre-instantiated in the background during start-up). Thank you.

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• How to reserve public API to internal usage in .NET?

  - by mark

  Dear ladies and sirs. Let me first present the case, which will explain my question. This is going to be a bit long, so I apologize in advance :-). I have objects and collections, which should support the Merge API (it is my custom API, the signature of which is immaterial for this question). This API must be internal, meaning only my framework should be allowed to invoke it. However, derived types should be able to override the basic implementation. The natural way to implement this pattern as I see it, is this: The Merge API is declared as part of some internal interface, let us say IMergeable. Because the interface is internal, derived types would not be able to implement it directly. Rather they must inherit it from a common base type. So, a common base type is introduced, which would implement the IMergeable interface explicitly, where the interface methods delegate to respective protected virtual methods, providing the default implementation. This way the API is only callable by my framework, but derived types may override the default implementation. The following code snippet demonstrates the concept: internal interface IMergeable { void Merge(object obj); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } void IMergeable.Merge(object obj) { Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } All is fine, provided a single common base type suffices, which is usually true for non collection types. The thing is that collections must be mergeable as well. Collections do not play nicely with the presented concept, because developers do not develop collections from the scratch. There are predefined implementations - observable, filtered, compound, read-only, remove-only, ordered, god-knows-what, ... They may be developed from scratch in-house, but once finished, they serve wide range of products and should never be tailored to some specific product. Which means, that either: they do not implement the IMergeable interface at all, because it is internal to some product the scope of the IMergeable interface is raised to public and the API becomes open and callable by all. Let us refer to these collections as standard collections. Anyway, the first option screws my framework, because now each possible standard collection type has to be paired with the respective framework version, augmenting the standard with the IMergeable interface implementation - this is so bad, I am not even considering it. The second option breaks the framework as well, because the IMergeable interface should be internal for a reason (whatever it is) and now this interface has to open to all. So what to do? My solution is this. make IMergeable public API, but add an extra parameter to the Merge method, I call it a security token. The interface implementation may check that the token references some internal object, which is never exposed to the outside. If this is the case, then the method was called from within the framework, otherwise - some outside API consumer attempted to invoke it and so the implementation can blow up with a SecurityException. Here is the modified code snippet demonstrating this concept: internal static class InternalApi { internal static readonly object Token = new object(); } public interface IMergeable { void Merge(object obj, object token); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } public void Merge(object obj, object token) { if (!object.ReferenceEquals(token, InternalApi.Token)) { throw new SecurityException("bla bla bla"); } Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } Of course, this is less explicit than having an internally scoped interface and the check is moved from the compile time to run time, yet this is the best I could come up with. Now, I have a gut feeling that there is a better way to solve the problem I have presented. I do not know, may be using some standard Code Access Security features? I have only vague understanding of it, but can LinkDemand attribute be somehow related to it? Anyway, I would like to hear other opinions. Thanks.

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• If I use a facade class with generic methods to access the JPA API, how should I provide additional processing for specific types?

  - by Shaun

  Let's say I'm making a fairly simple web application using JAVA EE specs (I've heard this is possible). In this app, I only have about 10 domain/data objects, and these are represented by JPA Entities. Architecturally, I would consider the JPA API to perform the role of a DAO. Of course, I don't want to use the EntityManager directly in my UI (JSF) and I need to manage transactions, so I delegate these tasks to the so-called service layer. More specifically, I would like to be able to handle these tasks in a single DataService class (often also called CrudService) with generic methods. See this article by Adam Bien for an example interface: http://www.adam-bien.com/roller/abien/entry/generic_crud_service_aka_dao My project differs from that article in that I can't use EJBs, so my service classes are essentially just named beans and I handle transactions manually. Regardless, what I want is a single interface for simple CRUD operations on my data objects because having a different class for each data type would lead to a lot of duplicate and/or unnecessary code. Ideally, my views would be able to use a method such as public <T> List<T> findAll(Class<T> type) { ... } to retrieve data. Using JSF, it might look something like this: <h:dataTable value="#{dataService.findAll(data.class)}" var="d"> ... </h:dataTable> Similarly, after validating forms, my controller could submit the data with a method such as: public <T> void add(T entity) { ... } Granted, you'd probably actually want to return something useful to the caller. In any case, this works well if your data can be treated as homogenous in this manner. Alas, it breaks down when you need to perform additional processing on certain objects before passing them on to JPA. For example, let's say I'm dealing with Books and Authors which have a many-to-many relationship. Each Book has a set of IDs referring to its authors, and each Author has a set of IDs referring to their books. Normally, JPA can manage this kind of relationship for you, but in some cases it can't (for example, the google app engine JPA provider doesn't support this). Thus, when I persist a new book for example, I may need to update the corresponding author entities. My question, then, is if there's an elegant way to handle this or if I should reconsider the sanity of my whole design. Here's a couple ways I see of dealing with it: The instanceof operator. I could use this to target certain classes when special processing is needed. Perhaps maintainability suffers and it isn't beautiful code, but if there's only 10 or so domain objects it can't be all that bad... could it? Make a different service for each entity type (ie, BookService and AuthorService). All services would inherit from a generic DataService base class and override methods if special processing is needed. At this point, you could probably also just call them DAOs instead. As always, I appreciate the help. Let me know if any clarifications are needed, as I left out many smaller details.

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• "undefined reference" error with namespace across multiple files

  - by user1330734

  I've looked at several related posts but no luck with this error. I receive this undefined reference error message below when my namespace exists across multiple files. If I compile only ConsoleTest.cpp with contents of Console.cpp dumped into it the source compiles. I would appreciate any feedback on this issue, thanks in advance. g++ Console.cpp ConsoleTest.cpp -o ConsoleTest.o -Wall /tmp/cc8KfSLh.o: In function `getValueTest()': ConsoleTest.cpp:(.text+0x132): undefined reference to `void Console::getValue<unsigned int>(unsigned int&)' collect2: ld returned 1 exit status Console.h #include <iostream> #include <sstream> #include <string> namespace Console { std::string getLine(); template <typename T> void getValue(T &value); } Console.cpp #include "Console.h" using namespace std; namespace Console { string getLine() { string str; while (true) { cin.clear(); if (cin.eof()) { break; // handle eof (Ctrl-D) gracefully } if (cin.good()) { char next = cin.get(); if (next == '\n') break; str += next; // add character to string } else { cin.clear(); // clear error state string badToken; cin >> badToken; cerr << "Bad input encountered: " << badToken << endl; } } return str; } template <typename T> void getValue(T &value) { string inputStr = Console::getLine(); istringstream strStream(inputStr); strStream >> value; } } ConsoleTest.cpp #include "Console.h" void getLineTest() { std::string str; std::cout << "getLinetest" << std::endl; while (str != "next") { str = Console::getLine(); std::cout << "<string>" << str << "</string>"<< std::endl; } } void getValueTest() { std::cout << "getValueTest" << std::endl; unsigned x = 0; while (x != 12345) { Console::getValue(x); std::cout << "x: " << x << std::endl; } } int main() { getLineTest(); getValueTest(); return 0; }

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• Problems with this code?

  - by J4C3N-14

  I'm trying to use this code which is an example taken from here https://gist.github.com/2383248 , but it is coming up with a error on the public void onClick which is Multiple markers at this line - implements android.view.View.OnClickListener.onClick - Syntax error, insert "}" to complete MethodBody, but when I add the brace it just throws another error after many tries and fails of different suggestions and ideas. It may be a syntax error and bad coding from me (just started learning to program) but does anyone have any ideas how to resolve this or point me in the right direction I would be very grateful. public class ICSCalendarActivity extends Activity implements View.OnClickListener{ Button button1; int year1; int month1; int day1; int ShiftPattern; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); button1 = (Button)findViewById(R.id.openButton); button1.setText("open"); button1.setOnClickListener(this); Bundle extras = getIntent().getExtras(); year1 = extras.getInt("year1"); day1 = extras.getInt("day1"); month1 = extras.getInt("month1"); ShiftPattern = extras.getInt("ShiftPattern"); } public void onClick(View v){ private static void addToCalendar(Context ICSCalendarActivity, final String title, final long dtstart, final long dtend) { final ContentResolver cr = ICSCalendarActivity.getContentResolver(); Cursor cursor ; if (Integer.parseInt(Build.VERSION.SDK) >= 8 ) cursor = cr.query(Uri.parse("content://com.android.calendar/calendars"), new String[]{ "_id", "displayname" }, null, null, null); else cursor = cr.query(Uri.parse("content://calendar/calendars"), new String[]{ "_id", "displayname" }, null, null, null); if ( cursor.moveToFirst() ) { final String[] calNames = new String[cursor.getCount()]; final int[] calIds = new int[cursor.getCount()]; for (int i = 0; i < calNames.length; i++) { calIds[i] = cursor.getInt(0); calNames[i] = cursor.getString(1); cursor.moveToNext(); } AlertDialog.Builder builder = new AlertDialog.Builder(ICSCalendarActivity); builder.setSingleChoiceItems(calNames, -1, new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { ContentValues cv = new ContentValues(); cv.put("calendar_id", calIds[which]); cv.put("title", title); cv.put("dtstart", dtstart ); cv.put("hasAlarm", 1); cv.put("dtend", dtend); Uri newEvent ; if (Integer.parseInt(Build.VERSION.SDK) >= 8 ) newEvent = cr.insert(Uri.parse("content://com.android.calendar/events"), cv); else newEvent = cr.insert(Uri.parse("content://calendar/events"), cv); if (newEvent != null) { long id = Long.parseLong( newEvent.getLastPathSegment() ); ContentValues values = new ContentValues(); values.put( "event_id", id ); values.put( "method", 1 ); values.put( "minutes", 15 ); // 15 minutes if (Integer.parseInt(Build.VERSION.SDK) >= 8 ) cr.insert( Uri.parse( "content://com.android.calendar/reminders" ), values ); else cr.insert( Uri.parse( "content://calendar/reminders" ), values ); } dialog.cancel(); } }); builder.create().show(); } cursor.close(); } } Thank you.

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• database design help for game / user levels / progress

  - by sprugman

  Sorry this got long and all prose-y. I'm creating my first truly gamified web app and could use some help thinking about how to structure the data. The Set-up Users need to accomplish tasks in each of several categories before they can move up a level. I've got my Users, Tasks, and Categories tables, and a UserTasks table which joins the three. ("User 3 has added Task 42 in Category 8. Now they've completed it.") That's all fine and working wonderfully. The Challenge I'm not sure of the best way to track the progress in the individual categories toward each level. The "business" rules are: You have to achieve a certain number of points in each category to move up. If you get the number of points needed in Cat 8, but still have other work to do to complete the level, any new Cat 8 points count toward your overall score, but don't "roll over" into the next level. The number of Categories is small (five currently) and unlikely to change often, but by no means absolutely fixed. The number of points needed to level-up will vary per level, probably by a formula, or perhaps a lookup table. So the challenge is to track each user's progress toward the next level in each category. I've thought of a few potential approaches: Possible Solutions Add a column to the users table for each category and reset them all to zero each time a user levels-up. Have a separate UserProgress table with a row for each category for each user and the number of points they have. (Basically a Many-to-Many version of #1.) Add a userLevel column to the UserTasks table and use that to derive their progress with some kind of SUM statement. Their current level will be a simple int in the User table. Pros & Cons (1) seems like by far the most straightforward, but it's also the least flexible. Perhaps I could use a naming convention based on the category ids to help overcome some of that. (With code like "select cats; for each cat, get the value from Users.progress_{cat.id}.") It's also the one where I lose the most data -- I won't know which points counted toward leveling up. I don't have a need in mind for that, so maybe I don't care about that. (2) seems complicated: every time I add or subtract a user or a category, I have to maintain the other table. I foresee synchronization challenges. (3) Is somewhere in between -- cleaner than #2, but less intuitive than #1. In order to find out where a user is, I'd have mildly complex SQL like: SELECT categoryId, SUM(points) from UserTasks WHERE userId={user.id} & countsTowardLevel={user.level} groupBy categoryId Hmm... that doesn't seem so bad. I think I'm talking myself into #3 here, but would love any input, advice or other ideas.

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• SQL SERVER – Shrinking NDF and MDF Files – Readers’ Opinion

  - by pinaldave

  Previously, I had written a blog post about SQL SERVER – Shrinking NDF and MDF Files – A Safe Operation. After that, I have written the following blog post that talks about the advantage and disadvantage of Shrinking and why one should not be Shrinking a file SQL SERVER – SHRINKFILE and TRUNCATE Log File in SQL Server 2008. On this subject, SQL Server Expert Imran Mohammed left an excellent comment. I just feel that his comment is worth a big article itself. For everybody to read his wonderful explanation, I am posting this blog post here. Thanks Imran! Shrinking Database always creates performance degradation and increases fragmentation in the database. I suggest that you keep that in mind before you start reading the following comment. If you are going to say Shrinking Database is bad and evil, here I am saying it first and loud. Now, the comment of Imran is written while keeping in mind only the process showing how the Shrinking Database Operation works. Imran has already explained his understanding and requests further explanation. I have removed the Best Practices section from Imran’s comments, as there are a few corrections. Comments from Imran - Before I explain to you the concept of Shrink Database, let us understand the concept of Database Files. When we create a new database inside the SQL Server, it is typical that SQl Server creates two physical files in the Operating System: one with .MDF Extension, and another with .LDF Extension. .MDF is called as Primary Data File. .LDF is called as Transactional Log file. If you add one or more data files to a database, the physical file that will be created in the Operating System will have an extension of .NDF, which is called as Secondary Data File; whereas, when you add one or more log files to a database, the physical file that will be created in the Operating System will have the same extension as .LDF. The questions now are, “Why does a new data file have a different extension (.NDF)?”, “Why is it called as a secondary data file?” and, “Why is .MDF file called as a primary data file?” Answers: Note: The following explanation is based on my limited knowledge of SQL Server, so experts please do comment. A data file with a .MDF extension is called a Primary Data File, and the reason behind it is that it contains Database Catalogs. Catalogs mean Meta Data. Meta Data is “Data about Data”. An example for Meta Data includes system objects that store information about other objects, except the data stored by the users. sysobjects stores information about all objects in that database. sysindexes stores information about all indexes and rows of every table in that database. syscolumns stores information about all columns that each table has in that database. sysusers stores how many users that database has. Although Meta Data stores information about other objects, it is not the transactional data that a user enters; rather, it’s a system data about the data. Because Primary Data File (.MDF) contains important information about the database, it is treated as a special file. It is given the name Primary Data file because it contains the Database Catalogs. This file is present in the Primary File Group. You can always create additional objects (Tables, indexes etc.) in the Primary data file (This file is present in the Primary File group), by mentioning that you want to create this object under the Primary File Group. Any additional data file that you add to the database will have only transactional data but no Meta Data, so that’s why it is called as the Secondary Data File. It is given the extension name .NDF so that the user can easily identify whether a specific data file is a Primary Data File or a Secondary Data File(s). There are many advantages of storing data in different files that are under different file groups. You can put your read only in the tables in one file (file group) and read-write tables in another file (file group) and take a backup of only the file group that has read the write data, so that you can avoid taking the backup of a read-only data that cannot be altered. Creating additional files in different physical hard disks also improves I/O performance. A real-time scenario where we use Files could be this one: Let’s say you have created a database called MYDB in the D-Drive which has a 50 GB space. You also have 1 Database File (.MDF) and 1 Log File on D-Drive and suppose that all of that 50 GB space has been used up and you do not have any free space left but you still want to add an additional space to the database. One easy option would be to add one more physical hard disk to the server, add new data file to MYDB database and create this new data file in a new hard disk then move some of the objects from one file to another, and put the file group under which you added new file as default File group, so that any new object that is created gets into the new files, unless specified. Now that we got a basic idea of what data files are, what type of data they store and why they are named the way they are, let’s move on to the next topic, Shrinking. First of all, I disagree with the Microsoft terminology for naming this feature as “Shrinking”. Shrinking, in regular terms, means to reduce the size of a file by means of compressing it. BUT in SQL Server, Shrinking DOES NOT mean compressing. Shrinking in SQL Server means to remove an empty space from database files and release the empty space either to the Operating System or to SQL Server. Let’s examine this through an example. Let’s say you have a database “MYDB” with a size of 50 GB that has a free space of about 20 GB, which means 30GB in the database is filled with data and the 20 GB of space is free in the database because it is not currently utilized by the SQL Server (Database); it is reserved and not yet in use. If you choose to shrink the database and to release an empty space to Operating System, and MIND YOU, you can only shrink the database size to 30 GB (in our example). You cannot shrink the database to a size less than what is filled with data. So, if you have a database that is full and has no empty space in the data file and log file (you don’t have an extra disk space to set Auto growth option ON), YOU CANNOT issue the SHRINK Database/File command, because of two reasons: There is no empty space to be released because the Shrink command does not compress the database; it only removes the empty space from the database files and there is no empty space. Remember, the Shrink command is a logged operation. When we perform the Shrink operation, this information is logged in the log file. If there is no empty space in the log file, SQL Server cannot write to the log file and you cannot shrink a database. Now answering your questions: (1) Q: What are the USEDPAGES & ESTIMATEDPAGES that appear on the Results Pane after using the DBCC SHRINKDATABASE (NorthWind, 10) ? A: According to Books Online (For SQL Server 2000): UsedPages: the number of 8-KB pages currently used by the file. EstimatedPages: the number of 8-KB pages that SQL Server estimates the file could be shrunk down to. Important Note: Before asking any question, make sure you go through Books Online or search on the Google once. The reasons for doing so have many advantages: 1. If someone else already has had this question before, chances that it is already answered are more than 50 %. 2. This reduces your waiting time for the answer. (2) Q: What is the difference between Shrinking the Database using DBCC command like the one above & shrinking it from the Enterprise Manager Console by Right-Clicking the database, going to TASKS & then selecting SHRINK Option, on a SQL Server 2000 environment? A: As far as my knowledge goes, there is no difference, both will work the same way, one advantage of using this command from query analyzer is, your console won’t be freezed. You can do perform your regular activities using Enterprise Manager. (3) Q: What is this .NDF file that is discussed above? I have never heard of it. What is it used for? Is it used by end-users, DBAs or the SERVER/SYSTEM itself? A: .NDF File is a secondary data file. You never heard of it because when database is created, SQL Server creates database by default with only 1 data file (.MDF) and 1 log file (.LDF) or however your model database has been setup, because a model database is a template used every time you create a new database using the CREATE DATABASE Command. Unless you have added an extra data file, you will not see it. This file is used by the SQL Server to store data which are saved by the users. Hope this information helps. I would like to as the experts to please comment if what I understand is not what the Microsoft guys meant. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Readers Contribution, Readers Question, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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