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• Buy or Build for web deployment?

  - by Cannonade

  I have been evaluating the wide range of installation and web deployment solutions available for Windows applications. I will just clarify here (without too much detail, these tools have been covered in other questions) my understanding of the options: NSIS - Free tool that generates setup executables. Small binary. Specialized, sometimes obtuse, scripting language. Inno Setup - Free tools for setup executables. Various binary compression schemes. Pascal scripting engine. WIX - Free toolset to generate MSI binaries. XML definitions language. WIX ClickThrough - Additional tools for packaging, web download and auto update detection (now part of WIX core). InstallShield - Commercial development environment for installation packaging. Generates MSI binaries. C-like InstallScript language. Wise - Commercial development environment for installation packaging. Generates MSI binaries. ClickOnce - Visual Studio supported framework for publishing applications to a webserver, with automatic detection of updates. No support for custom installation requirements (INI files, registry etc ...). Packages setup as an MSI binary. Install Aware - Commercial development environment for installation. Generates MSI binaries. Automatic Update framwork (Web Update). If I have missed any, please let me know. And found some useful discussions of these technologies on StackOverflow: Best Simple Install System Best choice for Windows installers Alternatives to ClickOnce I have worked with a few of these solutions, as well as a handful of proprietary internal installation solutions. They are mostly concerned with packing installations and providing a framework for developers to access the run time environment. With the growing requirement for web deployment and automatic software updates, I expected to find more of a consensus among developers on a framework for web delivery of software and subsequent updates, I haven't really found that consensus. There are certainly solutions available (ClickOnce, ClickThrough, InstallShield Update Service), but they each have considerable limitations (please correct me if I mis-represent any of these). I would be interested in a framework that provided some of the following: Third party hosting/management of updates. Access to client environment (INI files, registry, etc..). User registration/activation. Feedback/Error reporting This is leaving me with the strong impression that the best way to approach the web deployment problem is through a custom built proprietary solution (possibly leveraging existing installer packaging). I have seen this sort of solution work well for a number of successful applications: FileZilla - HTTP request to update.filezilla-project.org to check for updates, downloads an NSIS binary (I think) and then shuts down to run the install.

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• Double Buffering for Game objects, what's a nice clean generic C++ way?

  - by Gary

  This is in C++. So, I'm starting from scratch writing a game engine for fun and learning from the ground up. One of the ideas I want to implement is to have game object state (a struct) be double-buffered. For instance, I can have subsystems updating the new game object data while a render thread is rendering from the old data by guaranteeing there is a consistent state stored within the game object (the data from last time). After rendering of old and updating of new is finished, I can swap buffers and do it again. Question is, what's a good forward-looking and generic OOP way to expose this to my classes while trying to hide implementation details as much as possible? Would like to know your thoughts and considerations. I was thinking operator overloading could be used, but how do I overload assign for a templated class's member within my buffer class? for instance, I think this is an example of what I want: doublebuffer<Vector3> data; data.x=5; //would write to the member x within the new buffer int a=data.x; //would read from the old buffer's x member data.x+=1; //I guess this shouldn't be allowed If this is possible, I could choose to enable or disable double-buffering structs without changing much code. This is what I was considering: template <class T> class doublebuffer{ T T1; T T2; T * current=T1; T * old=T2; public: doublebuffer(); ~doublebuffer(); void swap(); operator=()?... }; and a game object would be like this: struct MyObjectData{ int x; float afloat; } class MyObject: public Node { doublebuffer<MyObjectData> data; functions... } What I have right now is functions that return pointers to the old and new buffer, and I guess any classes that use them have to be aware of this. Is there a better way?

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• Good working habits to observe in project development?

  - by Will Marcouiller

  As my development experience grows, I see fit to stick to best practices from here and there to build somehow my own working practices while observing the conventions, etc. I'm currently working on a project which my goals is to graduate the security access model from an environment's Active Directory to another environment's automatically. I don't know for any of you, but as far as I'm concerned, I meet some real difficulties sticking to only one way, then develop. I mean, I learn something new everyday while visiting SO, and recently wanted to get acquainted with generics. On the other hand, I better know the Façade pattern which proved to be very practical in transactional programming in process systems. This seems to be less practical for desktop application as there are plenty of variables to consider in a desktop application that you don't have to care in transactional programming, as you're playing only with information data. As for my current project, I have: Groups; Organizational Units; Users. Which are all considered an entry in the Active Directory. This points out to be a good candidate for generics, as also approached this way by Bart de Smett's Linq to AD on CodePlex. He has a DirectorySource<T>, and to manage let's say groups, then he instantiate a source with the proper type: var groups = new DirectorySource<Group>(); This seems to be very a good way of doing. Despite, I seem to go from one pattern to another and I don't seem to be able to strictly stick to one. While I'm aware that one must not stay with only one way of doing, since each pattern statisfies certain advantages, while also illustrating disadvantages under some usage conditions, I seem to want to develop with both patterns having a singleton Façade class with the underlying factories which represent the sub systems: GroupsFactory; UsersFactory; OrganizationalUnitsFactory. Each of the factories offers the possible operations for their respective entity (group, user, OU). To make a very long story short, I often have plenty of ideas while developping and this causes me some trouble, as I go from an idea to another feeling completely lost after a while. Yet I understand the advantages and disavantages, I have no trouble choosing from one pattern to another depending on the situation. Nevertheless, when it comes to programming itself, if I'm not part of a team, I feel sometimes like I can't do anything good. That is, because I can't stand not doing something "perfect" the first time. The role I play within the project is both: the project manager and the programmer. I am more comfortable in the project manager role, architectural role, analytical role than the developer's. Has any of you some good habbits to observe in project development? Thanks to you all! =)

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• How do I destruct data associated with an object after the object no longer exists?

  - by Phineas

  I'm creating a class (say, C) that associates data (say, D) with an object (say, O). When O is destructed, O will notify C that it soon will no longer exist :( ... Later, when C feels it is the right time, C will let go of what belonged to O, namely D. If D can be any type of object, what's the best way for C to be able to execute "delete D;"? And what if D is an array of objects? My solution is to have D derive from a base class that C has knowledge of. When the time comes, C calls delete on a pointer to the base class. I've also considered storing void pointers and calling delete, but I found out that's undefined behavior and doesn't call D's destructor. I considered that templates could be a novel solution, but I couldn't work that idea out. Here's what I have so far for C, minus some details: // This class is C in the above description. There may be many instances of C. class Context { public: // D will inherit from this class class Data { public: virtual ~Data() {} }; Context(); ~Context(); // Associates an owner (O) with its data (D) void add(const void* owner, Data* data); // O calls this when he knows its the end (O's destructor). // All instances of C are now aware that O is gone and its time to get rid // of all associated instances of D. static void purge (const void* owner); // This is called periodically in the application. It checks whether // O has called purge, and calls "delete D;" void refresh(); // Side note: sometimes O needs access to D Data *get (const void *owner); private: // Used for mapping owners (O) to data (D) std::map _data; }; // Here's an example of O class Mesh { public: ~Mesh() { Context::purge(this); } void init(Context& c) const { Data* data = new Data; // GL initialization here c.add(this, new Data); } void render(Context& c) const { Data* data = c.get(this); } private: // And here's an example of D struct Data : public Context::Data { ~Data() { glDeleteBuffers(1, &vbo); glDeleteTextures(1, &texture); } GLint vbo; GLint texture; }; }; P.S. If you're familiar with computer graphics and VR, I'm creating a class that separates an object's per-context data (e.g. OpenGL VBO IDs) from its per-application data (e.g. an array of vertices) and frees the per-context data at the appropriate time (when the matching rendering context is current).

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• Can GPU capabilities impact virtual machine performance?

  - by Dave White

  While this many not seem like a programming question directly, it impacts my development activities and so it seems like it belongs here. It seems that more and more developers are turning to virtual environments for development activities on their computers, SharePoint development being a prime example. Also, as a trainer, I have virtual training environments for all of the classes that I teach. I recently purchased a new Dell E6510 to travel around with. It has the i7 620M (Dual core, HyperThreaded cpu running at 2.66GHz) and 8 GB of memory. Reading the spec sheet, it sounded like it would be a great laptop to carry around and run virtual machines on. Getting the laptop though, I've been pretty disappointed with the user experience of developing in a virtual machine. Giving the Virtual Machine 4 GB of memory, it was slow and I could type complete sentences and watch the VM "catchup". My company has training laptops that we provide for our classes. They are Dell Precision M6400 Intel Core 2 Duo P8700 running at 2.54Ghz with 8 GB of memory and the experience on this laptops is night and day compared to the E6510. They are crisp and you barely aware that you are running in a virtual environment. Since the E6510 should be faster in all categories than the M6400, I couldn't understand why the new laptop was slower, so I did a component by component comparison and the only place where the E6510 is less performant than the M6400 is the graphics department. The M6400 is running a nVidia FX 2700m GPU and the E6510 is running a nVidia 3100M GPU. Looking at benchmarks of the two GPUs suggest that the FX 2700M is twice as fast as the 3100M. http://www.notebookcheck.net/Mobile-Graphics-Cards-Benchmark-List.844.0.html 3100M = 111th (E6510) FX 2700m = 47th (Precision M6400) Radeon HD 5870 = 8th (Alienware) The host OS is Windows 7 64bit as is the guest OS, running in Virtual Box 3.1.8 with Guest Additions installed on the guest. The IDE being used in the virtual environment is VS 2010 Premium. So after that long setup, my question is: Is the GPU significantly impacting the virtual machine's performance or are there other factors that I'm not looking at that I can use to boost the vm's performance? Do we now have to consider GPU performance when purchasing laptops where we expect to use virtualized development environments? Thanks in advance. Cheers, Dave

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• Synchronizing thread communication?

  - by Roger Alsing

  Just for the heck of it I'm trying to emulate how JRuby generators work using threads in C#. Also, I'm fully aware that C# haas built in support for yield return, I'm just toying around a bit. I guess it's some sort of poor mans coroutines by keeping multiple callstacks alive using threads. (even though none of the callstacks should execute at the same time) The idea is like this: The consumer thread requests a value The worker thread provides a value and yields back to the consumer thread Repeat untill worker thread is done So, what would be the correct way of doing the following? //example class Program { static void Main(string[] args) { ThreadedEnumerator<string> enumerator = new ThreadedEnumerator<string>(); enumerator.Init(() => { for (int i = 1; i < 100; i++) { enumerator.Yield(i.ToString()); } }); foreach (var item in enumerator) { Console.WriteLine(item); }; Console.ReadLine(); } } //naive threaded enumerator public class ThreadedEnumerator<T> : IEnumerator<T>, IEnumerable<T> { private Thread enumeratorThread; private T current; private bool hasMore = true; private bool isStarted = false; AutoResetEvent enumeratorEvent = new AutoResetEvent(false); AutoResetEvent consumerEvent = new AutoResetEvent(false); public void Yield(T item) { //wait for consumer to request a value consumerEvent.WaitOne(); //assign the value current = item; //signal that we have yielded the requested enumeratorEvent.Set(); } public void Init(Action userAction) { Action WrappedAction = () => { userAction(); consumerEvent.WaitOne(); enumeratorEvent.Set(); hasMore = false; }; ThreadStart ts = new ThreadStart(WrappedAction); enumeratorThread = new Thread(ts); enumeratorThread.IsBackground = true; isStarted = false; } public T Current { get { return current; } } public void Dispose() { enumeratorThread.Abort(); } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { if (!isStarted) { isStarted = true; enumeratorThread.Start(); } //signal that we are ready to receive a value consumerEvent.Set(); //wait for the enumerator to yield enumeratorEvent.WaitOne(); return hasMore; } public void Reset() { throw new NotImplementedException(); } public IEnumerator<T> GetEnumerator() { return this; } System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return this; } } Ideas?

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• Combinations and Permutations in F#

  - by Noldorin

  I've recently written the following combinations and permutations functions for an F# project, but I'm quite aware they're far from optimised. /// Rotates a list by one place forward. let rotate lst = List.tail lst @ [List.head lst] /// Gets all rotations of a list. let getRotations lst = let rec getAll lst i = if i = 0 then [] else lst :: (getAll (rotate lst) (i - 1)) getAll lst (List.length lst) /// Gets all permutations (without repetition) of specified length from a list. let rec getPerms n lst = match n, lst with | 0, _ -> seq [[]] | _, [] -> seq [] | k, _ -> lst |> getRotations |> Seq.collect (fun r -> Seq.map ((@) [List.head r]) (getPerms (k - 1) (List.tail r))) /// Gets all permutations (with repetition) of specified length from a list. let rec getPermsWithRep n lst = match n, lst with | 0, _ -> seq [[]] | _, [] -> seq [] | k, _ -> lst |> Seq.collect (fun x -> Seq.map ((@) [x]) (getPermsWithRep (k - 1) lst)) // equivalent: | k, _ -> lst |> getRotations |> Seq.collect (fun r -> List.map ((@) [List.head r]) (getPermsWithRep (k - 1) r)) /// Gets all combinations (without repetition) of specified length from a list. let rec getCombs n lst = match n, lst with | 0, _ -> seq [[]] | _, [] -> seq [] | k, (x :: xs) -> Seq.append (Seq.map ((@) [x]) (getCombs (k - 1) xs)) (getCombs k xs) /// Gets all combinations (with repetition) of specified length from a list. let rec getCombsWithRep n lst = match n, lst with | 0, _ -> seq [[]] | _, [] -> seq [] | k, (x :: xs) -> Seq.append (Seq.map ((@) [x]) (getCombsWithRep (k - 1) lst)) (getCombsWithRep k xs) Does anyone have any suggestions for how these functions (algorithms) can be sped up? I'm particularly interested in how the permutation (with and without repetition) ones can be improved. The business involving rotations of lists doesn't look too efficient to me in retrospect. Update Here's my new implementation for the getPerms function, inspired by Tomas's answer. Unfortunately, it's not really any fast than the existing one. Suggestions? let getPerms n lst = let rec getPermsImpl acc n lst = seq { match n, lst with | k, x :: xs -> if k > 0 then for r in getRotations lst do yield! getPermsImpl (List.head r :: acc) (k - 1) (List.tail r) if k >= 0 then yield! getPermsImpl acc k [] | 0, [] -> yield acc | _, [] -> () } getPermsImpl List.empty n lst

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• With EJB 2.1, is declaring references to resources in ejb-jar.xml required?

  - by zwerd328

  I'm using Weblogic 9.2 with a lot of MDBs. These MDBs access JDBC DataSources and write to both locally and externally managed JMS Destinations using local and foreign XAConnectionFactorys, respectively. Each MDB demarcates a container-managed JTA transaction that should be distributed amongst all of these resources. Below is an excerpt from my ejb-jar.xml for an MDB that consumes from a local Queue called "MyDestination" and produces to an IBM Websphere MQ Queue called "MyOtherDestination". These logical names are linked to physical objects in my weblogic-ejb-jar.xml file. Is it required to use the <resource-ref> and <message-destination-ref> tags to expose the ConnectionFactory and Queue to the MDB? If so, is it required by Weblogic or is it required by the J2EE spec? And for what purpose? For example, is it required to support XA transactionality? I'm already aware of the benefit of decoupling the administered objects from my MDB using names exposed to the naming context of the MDB. Is this the only value added when specifying these tags? In other words, is it acceptable to just reference these objects from my MDB using the InitialContext and the objects' fully-qualified names? <enterprise-bean> <message-driven> <ejb-name>MyMDB</ejb-name> <ejb-class>com.mycompany.MyMessageDrivenBean</ejb-class> <transaction-type>Container</transaction-type> <message-destination-type>javax.jms.Queue</message-destination> <message-destination-link>MyDestination</message-destination-link> <resource-ref> <res-ref-name>jms/myQCF</res-ref-name> <res-type>javax.jms.XAConnectionFactory</res-type> <res-auth>Container</res-auth> </resource-ref> <message-destination-ref> <message-destination-ref-name>jms/myOtherDestination</message-destination-ref-name> <message-destination-type>javax.jms.Queue</message-destination-type> <message-destination-usage>Produces</message-destination-usage> <message-destination-link>MyOtherDestination</message-destination-link> </message-destination-ref> </message-driven> <enterprise-bean>

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• Browser displays page without styles for a short moment (visual glitch)

  - by Pierre

  I have observed that, very infrequently, Internet Explorer (7 or 8, it does not matter) displays our web pages (www.epsitec.ch) a short time without applying the CSS. The layout appears completely broken, with everything displayed sequentially from top to bottom. When the page has finished loading, everything finally gets displayed properly. Our web pages do not use any fancy scripting, just two javascript inclusions for QuantCast and Google Analytics, done at the end of the page. By the way, we already had the issue before adding the QuantCast script. The CSS gets linked in the <head> section: <head> <title>Crésus Comptabilité</title> <link rel="icon" href="/favicon.ico" type="image/x-icon" /> <link rel="shortcut icon" href="http://www.epsitec.ch/favicon.ico" /> <link href="../../style.css" rel="stylesheet" type="text/css" /> ... </head> and then follows static HTML up to the final chunk which includes the JavaScript: ... <div id="account"> <a class="deselect" href="/account/login">Identifiez-vous</a> <script type="text/javascript"> _qoptions={qacct:"..."}; </script> <script type="text/javascript" src="http://edge.quantserve.com/quant.js"> </script> <noscript> <img src="..." style="display: none;" border="0" height="1" width="1"/> </noscript> </div> <div id="contact"> <a href="/support/contact">Contactez-nous</a> </div> <div id="ending"><!-- --></div> </div> <script type="text/javascript"> ... </script> <script type="text/javascript"> var pageTracker = _gat._getTracker("..."); pageTracker._initData(); pageTracker._trackPageview(); </script> </body> As this is a very short visual glitch, I have no idea what provokes it. Worse, I cannot reproduce it and it appears only on seldom occasions. How can I further investigate the cause of the glitch? Are there any best practices I should be aware of?

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• Django Multi-Table Inheritance VS Specifying Explicit OneToOne Relationship in Models

  - by chefsmart

  Hope all this makes sense :) I'll clarify via comments if necessary. Also, I am experimenting using bold text in this question, and will edit it out if I (or you) find it distracting. With that out of the way... Using django.contrib.auth gives us User and Group, among other useful things that I can't do without (like basic messaging). In my app I have several different types of users. A user can be of only one type. That would easily be handled by groups, with a little extra care. However, these different users are related to each other in hierarchies / relationships. Let's take a look at these users: - Principals - "top level" users Administrators - each administrator reports to a Principal Coordinators - each coordinator reports to an Administrator Apart from these there are other user types that are not directly related, but may get related later on. For example, "Company" is another type of user, and can have various "Products", and products may be supervised by a "Coordinator". "Buyer" is another kind of user that may buy products. Now all these users have various other attributes, some of which are common to all types of users and some of which are distinct only to one user type. For example, all types of users have to have an address. On the other hand, only the Principal user belongs to a "BranchOffice". Another point, which was stated above, is that a User can only ever be of one type. The app also needs to keep track of who created and/or modified Principals, Administrators, Coordinators, Companies, Products etc. (So that's two more links to the User model.) In this scenario, is it a good idea to use Django's multi-table inheritance as follows: - from django.contrib.auth.models import User class Principal(User): # # # branchoffice = models.ForeignKey(BranchOffice) landline = models.CharField(blank=True, max_length=20) mobile = models.CharField(blank=True, max_length=20) created_by = models.ForeignKey(User, editable=False, blank=True, related_name="principalcreator") modified_by = models.ForeignKey(User, editable=False, blank=True, related_name="principalmodifier") # # # Or should I go about doing it like this: - class Principal(models.Model): # # # user = models.OneToOneField(User, blank=True) branchoffice = models.ForeignKey(BranchOffice) landline = models.CharField(blank=True, max_length=20) mobile = models.CharField(blank=True, max_length=20) created_by = models.ForeignKey(User, editable=False, blank=True, related_name="principalcreator") modified_by = models.ForeignKey(User, editable=False, blank=True, related_name="principalmodifier") # # # Please keep in mind that there are other user types that are related via foreign keys, for example: - class Administrator(models.Model): # # # principal = models.ForeignKey(Principal, help_text="The supervising principal for this Administrator") user = models.OneToOneField(User, blank=True) province = models.ForeignKey( Province) landline = models.CharField(blank=True, max_length=20) mobile = models.CharField(blank=True, max_length=20) created_by = models.ForeignKey(User, editable=False, blank=True, related_name="administratorcreator") modified_by = models.ForeignKey(User, editable=False, blank=True, related_name="administratormodifier") I am aware that Django does use a one-to-one relationship for multi-table inheritance behind the scenes. I am just not qualified enough to decide which is a more sound approach.

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• Turning temporary stringstream to c_str() in single statement

  - by AshleysBrain

  Consider the following function: void f(const char* str); Suppose I want to generate a string using stringstream and pass it to this function. If I want to do it in one statement, I might try: f((std::ostringstream() << "Value: " << 5).str().c_str()); // error This gives an error: 'str()' is not a member of 'basic_ostream'. OK, so operator<< is returning ostream instead of ostringstream - how about casting it back to an ostringstream? 1) Is this cast safe? f(static_cast<std::ostringstream&>(std::ostringstream() << "Value: " << 5).str().c_str()); // incorrect output Now with this, it turns out for the operator<<("Value: ") call, it's actually calling ostream's operator<<(void*) and printing a hex address. This is wrong, I want the text. 2) Why does operator<< on the temporary std::ostringstream() call the ostream operator? Surely the temporary has a type of 'ostringstream' not 'ostream'? I can cast the temporary to force the correct operator call too! f(static_cast<std::ostringstream&>(static_cast<std::ostringstream&>(std::ostringstream()) << "Value: " << 5).str().c_str()); This appears to work and passes "Value: 5" to f(). 3) Am I relying on undefined behavior now? The casts look unusual. I'm aware the best alternative is something like this: std::ostringstream ss; ss << "Value: " << 5; f(ss.str().c_str()); ...but I'm interested in the behavior of doing it in one line. Suppose someone wanted to make a (dubious) macro: #define make_temporary_cstr(x) (static_cast<std::ostringstream&>(static_cast<std::ostringstream&>(std::ostringstream()) << x).str().c_str()) // ... f(make_temporary_cstr("Value: " << 5)); Would this function as expected?

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• How to access static members in a Velocity template?

  - by matt b

  I'm not sure if there is a way to do this in Velocity or not: I have a User POJO which a property named Status, which looks like an enum (but it is not, since I am stuck on Java 1.4), the definition looks something like this: public class User { // default status to User private Status status = Status.USER; public void setStatus(Status status) { this.status = status; } public Status getStatus() { return status; } And Status is a static inner class: public static final class Status { private String statusString; private Status(String statusString) { this.statusString = statusString; } public final static Status USER = new Status("user"); public final static Status ADMIN = new Status("admin"); public final static Status STATUS_X = new Status("blah"); //.equals() and .hashCode() implemented as well } With this pattern, a user status can easily be tested in a conditional such as if(User.Status.ADMIN.equals(user.getStatus())) ... ... without having to reference any constants for the status ID, any magic numbers, etc. However, I can't figure out how to test these conditionals in my Velocity template with VTL. I'd like to just print a simple string based upon the user's status, such as: Welcome <b>${user.name}</b>! <br/> <br/> #if($user.status == com.company.blah.User.Status.USER) You are a regular user #elseif($user.status == com.company.blah.User.Status.ADMIN) You are an administrator #etc... #end But this throws an Exception that looks like org.apache.velocity.exception.ParseErrorException: Encountered "User" at webpages/include/dashboard.inc[line 10, column 21] Was expecting one of: "[" ... From the VTL User Guide, there is no mention of accessing a Java class/static member directly in VTL, it appears that the right hand side (RHS) of a conditional can only be a number literal, string literal, property reference, or method reference. So is there any way that I can access static Java properties/references in a Velocity template? I'm aware that as a workaround, I could embed the status ID or some other identifier as a reference in my controller (this is a web MVC application using Velocity as the View technology), but I strongly do not want to embed any magic numbers or constants in the view layer.

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• Why does my JSF + Spring web application output JSF source code instead of interpreted HTML page?

  - by Corvus

  I'm new to both JSF and Spring Framework and I'm trying to figure out how to make them work together. My current problem is that application outputs my JSF files without interpreting them. Here are some snippets of my code which I believe might be relevant: dispatcher-servlet.xml <bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping"> <property name="mappings"> <props> <prop key="login.htm">loginController</prop> </props> </property> </bean> <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/pages/" p:suffix=".xhtml" /> <bean name="loginController" class="controller.LoginController" /> loginController public class LoginController extends MultiActionController { public ModelAndView login(HttpServletRequest request, HttpServletResponse response) throws Exception { System.out.println("LOGIN"); return new ModelAndView("login"); } WEB-INF/pages/login.xhtml <?xml version='1.0' encoding='UTF-8' ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html"> <h:head> <title>#{message.log}</title> </h:head> <h:body> <h:form> <h:outputLabel value="#{message.username}" for="userName"> <h:inputText id="userName" value="#{User.name}" /> </h:outputLabel> <h:commandButton value="#{message.loggin}" action="#{User.login}" /> </h:form> </h:body> </html> Any ideas where the problem might be? Does this code make any sense at all? I'm well aware of fact, that probably completely sucks and I'll be glad to here WHY it sucks and how to make it better. Thanks :)

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• How do I get the next token in a Cstring if I want to use it as an int? (c++)

  - by Van

  My objective is to take directions from a user and eventually a text file to move a robot. The catch is that I must use Cstrings(such as char word[];) rather than the std::string and tokenize them for use. the code looks like this: void Navigator::manualDrive() { char uinput[1]; char delim[] = " "; char *token; cout << "Enter your directions below: \n"; cin.ignore(); cin.getline (uinput, 256); token=strtok(uinput, delim); if(token == "forward") { int inches; inches=token+1; travel(inches); } } I've never used Cstrings I've never tokenized anything before, and I don't know how to write this. Our T.A.'s expect us to google and find all the answers because they are aware we've never been taught these methods. Everyone in my lab is having much more trouble than usual. I don't know the code to write but I know what I want my program to do. I want it to execute like this: 1) Ask for directions. 2) cin.getline the users input 3) tokenize the inputed string 4) if the first word token == "forward" move to the next token and find out how many inches to move forward then move forward 5) else if the first token == "turn" move to the next token. if the next token == "left" move to the next token and find out how many degrees to turn left I will have to do this for forward x, backward x, turn left x, turn right x, and stop(where x is in inches or degrees). I already wrote functions that tell the robot how to move forward an inch and turn in degrees. I just need to know how to convert the inputted strings to all lowercase letters and move from token to token and convert or extract the numbers from the string to use them as integers. If all is not clear you can read my lab write up at this link: http://www.cs.utk.edu/~cs102/robot_labs/Lab9.html If anything is unclear please let me know, and I will clarify as best I can.

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• How to use Crtl in a Delphi unit in a C++Builder project? (or link to C++Builder C runtime library)

  - by Craig Peterson

  I have a Delphi unit that is statically linking a C .obj file using the {$L xxx} directive. The C file is compiled with C++Builder's command line compiler. To satisfy the C file's runtime library dependencies (_assert, memmove, etc), I'm including the crtl unit Allen Bauer mentioned here. unit FooWrapper; interface implementation uses Crtl; // Part of the Delphi RTL {$L FooLib.obj} // Compiled with "bcc32 -q -c foolib.c" procedure Foo; cdecl; external; end. If I compile that unit in a Delphi project (.dproj) everthing works correctly. If I compile that unit in a C++Builder project (.cbproj) it fails with the error: [ILINK32 Error] Fatal: Unable to open file 'CRTL.OBJ' And indeed, there isn't a crtl.obj file in the RAD Studio install folder. There is a .dcu, but no .pas. Trying to add crtdbg to the uses clause (the C header where _assert is defined) gives an error that it can't find crtdbg.dcu. If I remove the uses clause, it instead fails with errors that __assert and _memmove aren't found. So, in a Delphi unit in a C++Builder project, how can I export functions from the C runtime library so they're available for linking? I'm already aware of Rudy Velthuis's article. I'd like to avoid manually writing Delphi wrappers if possible, since I don't need them in Delphi, and C++Builder must already include the necessary functions. Edit For anyone who wants to play along at home, the code is available in Abbrevia's Subversion repository at https://tpabbrevia.svn.sourceforge.net/svnroot/tpabbrevia/trunk. I've taken David Heffernan's advice and added a "AbCrtl.pas" unit that mimics crtl.dcu when compiled in C++Builder. That got the PPMd support working, but the Lzma and WavPack libraries both fail with link errors: [ILINK32 Error] Error: Unresolved external '_beginthreadex' referenced from ABLZMA.OBJ [ILINK32 Error] Error: Unresolved external 'sprintf' referenced from ABWAVPACK.OBJ [ILINK32 Error] Error: Unresolved external 'strncmp' referenced from ABWAVPACK.OBJ [ILINK32 Error] Error: Unresolved external '_ftol' referenced from ABWAVPACK.OBJ AFAICT, all of them are declared correctly, and the _beginthreadex one is actually declared in AbLzma.pas, so it's used by the pure Delphi compile as well. To see it yourself, just download the trunk (or just the "source" and "packages" directories), disable the {$IFDEF BCB} block at the bottom of AbDefine.inc, and try to compile the C++Builder "Abbrevia.cbproj" project.

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• Implementing rounded corners on slide down navigation menu

  - by Nick

  I am working on the slide down menu you can see here. I have rounded corners on both ul#navigation and ul.subnavigation. When the submenu slides down it is possible to see the border at the bottom of ul.subnavigation overlap with the content of ul#navigation, when I would like it to slide down smoothly, without the 'flicker'. I am aware that this issue is caused by the rounded corners. I need ul.subnavigation to cover the rounded corners at the bottom of ul#navigation when the menu drops down, without seeing the double border-bottom issue. I hope this is clear! Code is below. Thanks, Nick HTML <ul id="navigation"> <li class="dropdown"><a href="#">menu</a> <ul class="sub_navigation"> <li><a href="#">home</a></li> <li><a href="#">help</a></li> <li><a href="#">disable tips</a></li> </ul> </li> </ul> JQUERY $('.dropdown').hover(function() { $(this).find('.sub_navigation').slideToggle(); });? CSS ul#navigation, ul.sub_navigation { margin:0; padding:0; list-style-type:none; min-width:100px; background-color: white; font-size:15px; font-family: Trebuchet MS; text-align: center; -khtml-border-radius: 0 0 5px 5px; -moz-border-radius: 0 0 5px 5px; -webkit-border-radius: 0 0 5px 5px; border-radius: 0 0 5px 5px; border:1px black solid; border-top:none; } ul.sub_navigation { margin-left:-1px; position: absolute; top:28px; } ul#navigation { float:left; position:absolute; top:0; } ul#navigation li { float:left; min-width:100px; } ul.sub_navigation { position:absolute; display:none; } ul.sub_navigation li { clear:both; } a, a:active, a:visited { display:block; padding:7px; }

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• What are the Options for Storing Hierarchical Data in a Relational Database?

  - by orangepips

  Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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• iPhone Image Resources, ICO vs PNG, app bundle filesize

  - by Jasarien

  My application has a collection of around 1940 icons that are used throughout. They're currently in ICO and new images provided to me come in ICO format too. I have noticed that they contain a 16x16 and 32x32 representation of each icon in one file. Each file is roughly 4KB in filesize (as reported by finder, but ls reports that they vary from being ~1000 bytes to 5000 bytes) A very small number of these icons only contain the 32x32 representation, and as a result are only around 700 bytes in size. Currently I am bundling these icons with my application and they are inflating the size of the app a bit more than I would like. Altogether, the images total just about 25.5MB. Xcode must do some kind of compression because the resulting app bundle is about 12.4MB. Compressing this further into a ZIP (as it would be when submitted to the App Store), results in a final file of 5.8MB. I'm aware that the maximum limit for over the air App Store downloads has been raised to 20MB since the introduction of the iPad (I'm not sure if that extends to iPhone apps as well as iPad apps though, if not the limit would be 10MB). My worry is that new icons are going to be added (sometimes up to 10 icons per week), and will continue to inflate the app bundle over time. What is the best way to distribute these icons with my app? Things I've tried and not had much success with: Converting the icons from ICO to PNG: I tried this in the hopes that the pngcrush utility would help out with the filesize. But it appears that it doesn't make much of a difference between a normal PNG and a crushed png (I believe it just optimises the image for display on the iPhone's GPU rather than compress it's size). Also in going from ICO to PNG actually increased the size of the icon file... Zipping the images, and then uncompressing them on first run. While this did reduce the overall image sizes, I found that the effort needed to unzip them, copy them to the documents folder and ensure that duplication doesn't happen on upgrades was too much hassle to be worth the benefit. Also, on original and 3G iPhones unzipping and copying around 25MB of images takes too long and creates a bad experience... Things I've considered but not yet tried: Instead of distributing the icons within the app bundle, host them online, and download each icon on demand (it depends on the user's data as to which icons will actually be displayed and when). Issues with this is that bandwidth costs money, and image downloads will be bandwidth intensive. However, my app currently has a small userbase of around 5,500 users (of which I estimate around 1500 to be active based on Flurry stats), and I have a huge unused bandwidth allowance with my current hosting package. So I'm open to thoughts on how to solve this tricky issue.

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• Chrome extension: sendMessage doesn't work

  - by user3334776

  I've already read the documentation from Google on 'message passing' a few times and have probably looked at over 10 other questions with the same problem and already tried quiet a few variations of most of their "solutions" and of what I have below... This is black magic, right? Either way, here it goes. Manifest File: { "manifest_version" : 2, "name" : "Message Test", "version" : "1.0", "browser_action": { "default_popup": "popup.html" }, "background": { "scripts": ["background.js"] }, "content_scripts": [ { "matches" : ["<all_urls>"], "js": ["message-test.js"] } ] } I'm aware extensions aren't suppose to use inline JS, but I'm leaving this in so the original question can be left as it was since I still can't get the message to send from the background page, When I switch from the popup to the background, I removed the appropriate lines from the manifest.json popup.html file: <html> <head> <script> chrome.tabs.query({active: true, currentWindow: true}, function(tabs) { chrome.tabs.sendMessage(tabs[0].id, {greeting: "hello", theMessage: "Why isn\'t this working?"}, function(response) { console.log(response.farewell); }); }); </script> </head> <body> </body> </html> OR background.js file: chrome.tabs.query({active: true, currentWindow: true}, function(tabs) { chrome.tabs.sendMessage(tabs[0].id, {greeting: "hello", theMessage: "Why isn\'t this working?"}, function(response) { console.log(response.farewell); }); }); message-test.js file: var Mymessage; chrome.runtime.onMessage.addListener(function(message, sender, sendResponse) { if (message.greeting == "hello"){ Mymessage = message.theMessage; alert(Mymessage); } else{ sendResponse({}); } }); No alert(Mymessage) goes off. I'm also trying to execute this after pressing a button from a popup and having a window at a specified url, but that's a later issue. The other files can be found here except with the background.js content wrapped in an addEventListener("click"....: http://pastebin.com/KhqxLx5y AND http://pastebin.com/JaGcp6tj

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• SQL/Schema comparison and upgrade

  - by Workshop Alex

  I have a simple situation. A large organisation is using several different versions of some (desktop) application and each version has it's own database structure. There are about 200 offices and each office will have it's own version, which can be one of 7 different ones. The company wants to upgrade all applications to the latest versions, which will be version 8. The problem is that they don't have a separate database for each version. Nor do they have a separate database for each office. They have one single database which is handled by a dedicated server, thus keeping things like management and backups easier. Every office has it's own database schema and within the schema there's the whole database structure for their specific application version. As a result, I'm dealing with 200 different schema's which need to be upgraded, each with 7 possible versions. Fortunately, every schema knows the proper version so checking the version isn't difficult. But my problem is that I need to create upgrade scripts which can upgrade from version 1 to version 2 to version 3 to etc... Basically, all schema's need to be bumped up one version until they're all version 8. Writing the code that will do this is no problem. the challenge is how to create the upgrade script from one version to the other? Preferably with some automated tool. I've examined RedGate's SQL Compare and Altova's DatabaseSpy but they're not practical. Altova is way too slow. RedGate requires too much processing afterwards, since the generated SQL Script still has a few errors and it refers to the schema name. Furthermore, the code needs to become part of a stored procedure and the code generated by RedGate doesn't really fit inside a single procedure. (Plus, it's doing too much transaction-handling, while I need everything within a single transaction. I have been considering using another SQL Comparison tool but it seems to me that my case is just too different from what standard tools can deliver. So I'm going to write my own comparison tool. To do this, I'll be using ADOX with Delphi to read the catalogues for every schema version in the database, then use this to write the SQL Statements that will need to upgrade these schema's to their next version. (Comparing 1 with 2, 2 with 3, 3 with 4, etc.) I'm not unfamiliar with generating SQL-Script-Generators so I don't expect too many problems. And I'll only be upgrading the table structures, not any of the other database objects. So, does anyone have some good tips and tricks to apply when doing this kind of comparisons? Things to be aware of? Practical tips to increase speed?

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• How to Load Dependent Files on Demand + Check if They're Loaded or Not?

  - by br4inwash3r

  I'm trying to implement an assets/dependency loader that i've found from an old article at 24Ways.org. most of you might be familiar with it. it's from this article by Christian Heilmann: http://24ways.org/2007/keeping-javascript-dependencies-at-bay i've modified the script to load CSS files as well. and it's now quite close to what i want. but i still need to do some checking to see wether an asset have been completely loaded or not. just wondering if you guys have any ideas :) here's what my script currently looked like: var assetLoader = { assets: { products: { js: 'products.js', css: 'products.css', loaded: false }, articles: { js: 'articles.js', css: 'articles.css', loaded: false }, [...] cycle: { js: 'jquery.cycle.min.js', loaded: false }, swfobject: { js: 'jquery.swfobject.min.js', loaded: false } }, add: function(asset) { var comp = assetLoader.assets[asset]; var path = '/path/to/assets/'; if (comp && comp.loaded == false) { if (comp.js) { // load js var js = document.createElement('script'); js.src = path + 'js/' + comp.js; js.type = 'text/javascript'; js.charset = 'utf-8'; // append to document document.getElementsByTagName('body')[0].appendChild(js); } if (comp.css) { // load css var css = document.createElement('link'); css.rel = 'stylesheet'; css.href = path + 'css/' + comp.css; css.type = 'text/css'; css.media = 'screen, projection'; css.charset = 'utf-8'; // append to document document.getElementsByTagName('head')[0].appendChild(css); } } }, check: function(asset) { assetLoader.assets[asset].loaded = true; } } Christian explains this method in his article in great detail. I don't want to confuse you guys anymore with my bad english :P and here's an example of how i run the script: ... // load jquery cycle plugin if (page=='tvc' || page=='products') { if (!assetLoader.assets.cycle.loaded) { assetLoader.add('cycle'); } } // load products page assets if (!assetLoader.assets.products.loaded) { assetLoader.add('products'); } ... this kind of approach is very problematic though. coz assets loads asynchronously, which means some of the code inside products.js that depends on jquery.cycle.js might continue running before jquery.cycle.js is even loaded resulting in errors. while i'm quite aware that scripts can be attached with an onload event, i'm just not really sure how to implement it to my script. anyone care to help me? please... :P

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• Self updating app, wont overwrite existing app, using Android packagemanager?

  - by LokiSinclair

  I know there are plenty of questions about this on here, but I've tried everything (but the correct 'thing', obviously!) and nothing seems to shine any light on the problem I'm having. I've written an app (for a customer), which is designed to be hosted on their own server. The app references a simple text file with the latest version code in it and checks it against it's own version. If it's out of date it goes off and downloads the update. Everything is working as intended up to this point. I use the: Intent i = new Intent(Intent.ACTION_VIEW); i.setDataAndType(Uri.fromFile(outputFile), "application/vnd.android.package-archive"); i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); startActivity(i); ...code to start the install process of the newly downloaded .apk file. And that all starts as I would expect. I click on "Install" - when I'm prompted to confirm the overwriting of the current app, with the new. It starts, and then displays: App not installed. And existing package by the same name with a conflicting signature is already installed. Now I'm aware that Android can't have multiple applications sharing the same package name, which is fine, but nothing comes up in LogCat and I can only assume that the OS is annoyed at me attempting to 'update' my app, even though I'm going through all the correct channels and using the inbuilt package manager to do it for me! Can anyone tell me what the OS is moaning about? I'm not attempting to install two apps side by side, I want it to update it, which it starts to do, and then gets really confused. Is it something to do with me using the same keystore for signing the packages? I highly doubt it as I've used the same keystores previously to handle updates to games and the like, but I just can't figure out what it's complaining about. Hopefully someone out there has had this issue and solved it, and can point me in the right direction. I'm flying a bit blind with the limited information it's giving me :( Cheers.

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• Infinite loop when adding a row to a list in a class in python3

  - by Margaret

  I have a script which contains two classes. (I'm obviously deleting a lot of stuff that I don't believe is relevant to the error I'm dealing with.) The eventual task is to create a decision tree, as I mentioned in this question. Unfortunately, I'm getting an infinite loop, and I'm having difficulty identifying why. I've identified the line of code that's going haywire, but I would have thought the iterator and the list I'm adding to would be different objects. Is there some side effect of list's .append functionality that I'm not aware of? Or am I making some other blindingly obvious mistake? class Dataset: individuals = [] #Becomes a list of dictionaries, in which each dictionary is a row from the CSV with the headers as keys def field_set(self): #Returns a list of the fields in individuals[] that can be used to split the data (i.e. have more than one value amongst the individuals def classified(self, predicted_value): #Returns True if all the individuals have the same value for predicted_value def fields_exhausted(self, predicted_value): #Returns True if all the individuals are identical except for predicted_value def lowest_entropy_value(self, predicted_value): #Returns the field that will reduce <a href="http://en.wikipedia.org/wiki/Entropy_%28information_theory%29">entropy</a> the most def __init__(self, individuals=[]): and class Node: ds = Dataset() #The data that is associated with this Node links = [] #List of Nodes, the offspring Nodes of this node level = 0 #Tree depth of this Node split_value = '' #Field used to split out this Node from the parent node node_value = '' #Value used to split out this Node from the parent Node def split_dataset(self, split_value): fields = [] #List of options for split_value amongst the individuals datasets = {} #Dictionary of Datasets, each one with a value from fields[] as its key for field in self.ds.field_set()[split_value]: #Populates the keys of fields[] fields.append(field) datasets[field] = Dataset() for i in self.ds.individuals: #Adds individuals to the datasets.dataset that matches their result for split_value datasets[i[split_value]].individuals.append(i) #<---Causes an infinite loop on the second hit for field in fields: #Creates subnodes from each of the datasets.Dataset options self.add_subnode(datasets[field],split_value,field) def add_subnode(self, dataset, split_value='', node_value=''): def __init__(self, level, dataset=Dataset()): My initialisation code is currently: if __name__ == '__main__': filename = (sys.argv[1]) #Takes in a CSV file predicted_value = "# class" #Identifies the field from the CSV file that should be predicted base_dataset = parse_csv(filename) #Turns the CSV file into a list of lists parsed_dataset = individual_list(base_dataset) #Turns the list of lists into a list of dictionaries root = Node(0, Dataset(parsed_dataset)) #Creates a root node, passing it the full dataset root.split_dataset(root.ds.lowest_entropy_value(predicted_value)) #Performs the first split, creating multiple subnodes n = root.links[0] n.split_dataset(n.ds.lowest_entropy_value(predicted_value)) #Attempts to split the first subnode.

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• MATLAB plot moving data points in seperate subplots simutaneously

  - by Nate B.

  I wish to visualize the movement of a data point throughout space across a period of time within MATLAB. However, the way I want my figure to display is such that only a single instant is plotted at any given time. That was easy, I simply created a for loop to update my 3D plot display for every set of coordinates (x,y,z) in my data. However, I wish to display 4 different viewing angles of this plot at all times. I am well aware of how to setup subplots within MATLAB, that is not the issue. My issue is getting all 4 of these subplots to execute simultaneously so that all 4 subplots are always displaying the same point in time. I would appreciate if anyone could suggest how to handle this issue. As requested, my code for a figure with a single plot is shown below: datan = DATA; %data in form of x,y,z,a,b,c by column for row# of time points tib=zeros(size(datan,1),12); tib(:,1:3) = datan(:,1:3); tib_ref=tib(1,1:3); for i=1:size(datan,1) tib(i,1:3)=tib(i,1:3)-tib_ref; end angle_to_dircos close all figure('Name','Directions (Individual Cycles)','NumberTitle','off') for cc=1:2 hold off for bb=1:10:size(tib,1); scatter3(tib(bb,1),tib(bb,2),tib(bb,3),'green','filled'); %z and y axes are flipped in polhemus system hold on p0 = [tib(bb,1),tib(bb,2),tib(bb,3)]; p1 = [tib(bb,1)+10*tib(bb,4),tib(bb,2)+10*tib(bb,5),tib(bb,3)+10*tib(bb,6)]; p2 = [tib(bb,1)+10*tib(bb,7),tib(bb,2)+10*tib(bb,8),tib(bb,3)+10*tib(bb,9)]; p3 = [-(tib(bb,1)+100*tib(bb,10)),-(tib(bb,2)+100*tib(bb,11)),-(tib(bb,3)+100*tib(bb,12))]; vectarrow(p0,p1,1,0,0) hold on vectarrow(p0,p2,0,1,0) hold on vectarrow(p0,p3,0,0,1) hold on az = 90; el = 0; view(az, el); xlim([-50,50]); ylim([-50,50]); zlim([-50,50]); xlabel('distance from center in X'); ylabel('distance from center in Y'); zlabel('distance from center in Z'); title('XYZ Scatter Plots of Tracker Position'); hold on plot3(0,0,0,'sk','markerfacecolor',[0,0,0]); p0 = [0,0,0]; p1 = [10,0,0]; p2 = [0,10,0]; p3 = [0,0,100]; vectarrow(p0,p1,1,0,0) hold on vectarrow(p0,p2,0,1,0) hold on vectarrow(p0,p3,1,0,1) drawnow; end end

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• how to design this relation in a DB schema

  - by raticulin

  I have a table Car in my db, one of the columns is purchaseDate. I want to be able to tag every car with a number of Policies (limited to 10 policies). Each policy has a time to life (ttl, a duration of time, like '5 years', '10 months' etc), that is, for how long since the car's purchaseDate the policy can be applied. I need to perform the following actions: when inserting a Car, it will be set with a number of Policies (at least one is set) sometimes a Car will be updated to add/remove a Policy searches must be done taking into account date/policies, for example: 'select all cars that are not covered by any policy as of today' My current design is (pol0..pol9 are the policies): CREATE TABLE Car ( id int NOT NULL IDENTITY(1,1), purchaseDate datetime NOT NULL, //more stuff... pol0 smallint default NULL, pol1 smallint default NULL, pol2 smallint default NULL, pol3 smallint default NULL, pol4 smallint default NULL, pol5 smallint default NULL, pol6 smallint default NULL, pol7 smallint default NULL, pol8 smallint default NULL, pol9 smallint default NULL, PRIMARY KEY (id) ) CREATE TABLE Policy ( id smallint NOT NULL, name varchar(50) collate Latin1_General_BIN NOT NULL, ttl varchar(100) collate Latin1_General_BIN NOT NULL, PRIMARY KEY (id) ) The problem I am facing is that the sql to perform the query above is a nightmare to write. As I don't know in which column each policy can be, so I have to check all columns for every policy etc etc. So I am wondering wether it is worth changing this. My questions are: The smallint as Policy id was chosen instead of an 'int IDENTITY' in order to save some space as there are going to be millions of Car records. It just adds complexity when creating a Policy as we must handle the id etc. Was it worth doing this? I am thinking that maybe there is a much better design? Obviously we could move the policy/car relation to its own table CarPolicy, benefits would be: no limit on 10 policies per car adding/removing etc much easier when only the default policy is applied (when no others are applied one called Default policy is applied), we could signal that by not having any entry in CarPolicy, now this is just done inserting the Default policy id in one of the columns. The cons are that we would need to change the DB, ORM classes etc. What would you recommend? Maybe there is another smart way to implement this that we are not aware without using the CarPolicy table?

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