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• Class lookup structure array in C++

  - by wyatt

  I'm trying to create a structure array which links input strings to classes as follows: struct {string command; CommandPath cPath;} cPathLookup[] = { {"set an alarm", AlarmCommandPath}, {"send an email", EmailCommandPath}, {"", NULL} }; which will be used as follows: CommandPath *cPath = NULL; string input; getline(cin, input); for(int i = 0; cPathLookup[i] != ""; i++) { if(cPathLookup[i].command == input) cPath = new cPathLookup[i].cPath; } Obviously, this code is meaningless, but I think my intention is apparent - depending on input, I'd like cPath to be initialized as either a new AlarmCommandPath or a new EmailCommandPath. I could handle it with a function returning an instance depending on input, but a whole sequence of ifs just seems inelegant. I should also note that, in case it's not apparent and important, that AlarmCommandPath and EmailCommandPath are derived from CommandPath, and CommandPath is an abstract class. Thanks for any help you can offer. EDIT: I just noticed that, in spite of CommandPath being abstract, I have a declaration: CommandPath *cPath = NULL; in working code. Why does that compile?

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• Is there an efficient algorithm to distribute resources in a way that both avoids conflict and allows bias?

  - by Steve V.

  Background (Skip this if you only care about the algorithm) At the university where I work, one of the biggest hassles in our department is classroom scheduling. For illustration purposes and to lay out the scope of the problem, here's how we do scheduling now: Professors give us a list of the classes they're teaching with the time slots they'd prefer to teach, ranked in order of priority (most desired to least desired). Administration gives us a list of the rooms we may assign along with the times those rooms are available for our department's use. We start assigning professors to rooms trying (at first) to take into account the preferences of the various professors. Inevitably, conflicts arise, professors start asking for changes, and the plan falls to pieces somewhere around professor number 30, at which point we start assigning rooms basically wherever we can fit them in, crumpled pieces of paper are everywhere, and nobody's happy. (If you've ever wondered why your class was at 9.30 in the morning on Thursday but 4 pm every other day, now you know) I have been asked to quietly investigate whether software could do this more optimally. The Actual Question Is there an algorithm to efficiently schedule a set of resources such that the following criteria are met: The algorithm must never assign two professors to the same room at the same time. The task is not complete until every professor has been assigned a room / time. The algorithm need not worry about having too many professors for the amount of time slots available. (We're not that well funded.) As much as is possible the algorithm should respect the scheduling preferences of the individual professors. I feel like I can't be the first one to ask this. Is there a efficient algorithm for this, or is this the sort of problem that can only be brute-forced?

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• How can I create a .jar file?

  - by Roman

  In the tutorial I found out that jar files can be created in the following way: jar cf jar-file input-file(s) However, it was not clear what are the input-file(s). Is that .java files or .class files? From the examples on the same page I can assume that should be .class files. But now it is not clear which .class files should I put there. After the compilation of .java files I have a lot of .class files. One of the reason of that is that I have a lot files like that: GameWindow$2$10class, GameWindow$2$7.class and so on. Should I include all of them into the command line for the creation of the .jar file? To run my application I use java Game. So, my be I need to use only Game.class file when I create a .jar file? On the other hand other class files corresponds to classes used by the application. My software use external libraries (during compilation I specify .jar files of these libraries). Will .jar file of my application be able to run on the computer which does not contain the .jar file of used library?

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• Mercurial: Class library that will exist for both .NET 3.5 and 4.0?

  - by Lasse V. Karlsen

  I have a rather big class library written in .NET 3.5 that I'd like to upgrade to make available for .NET 4.0 as well. In that process, I will rip out a lot of old junk, and rewrite some code to better take advantage of the new classes and support in .NET 4.0 (like TPL.) The class libraries will thus diverge, but still be similar enough that some bug-fixes can be done to both in the same manner. How should I best organize this class library in Mercurial? I'm using Kiln (fogbugz) if that matters. I'm thinking: Named branches in one repository, can then transplant any bugfixes from one to the other Unnamed branches in one repository, can also transplant, but I think this will look messy Separate repositories, will have to reimplement the bugfixes (or use a non-mercurial-integraded compare tool to help me) What would you do? (any other alternatives that I haven't though of is welcome as well.) Note that the class libraries will diverge pretty heavily in areas, I have some remnants of old collection-type code that does something similar to Linq that I will remove, and some code that uses it that I will rewrite to use the Linq-methods instead. As such, just copying the project files and using #if NET40..#endif sections is not going to work out. Also, the 3.5 version of the class library will not be getting many new features, mostly just critical bug-fixes, so keeping both versions equally "alive" isn't really necessary. Thus, separate copies of all the files are good enough.

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• Can you explain this generics behavior and if I have a workaround?

  - by insta

  Sample program below: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GenericsTest { class Program { static void Main(string[] args) { IRetrievable<int, User> repo = new FakeRepository(); Console.WriteLine(repo.Retrieve(35)); } } class User { public int Id { get; set; } public string Name { get; set; } } class FakeRepository : BaseRepository<User>, ICreatable<User>, IDeletable<User>, IRetrievable<int, User> { // why do I have to implement this here, instead of letting the // TKey generics implementation in the baseclass handle it? //public User Retrieve(int input) //{ // throw new NotImplementedException(); //} } class BaseRepository<TPoco> where TPoco : class,new() { public virtual TPoco Create() { return new TPoco(); } public virtual bool Delete(TPoco item) { return true; } public virtual TPoco Retrieve<TKey>(TKey input) { return null; } } interface ICreatable<TPoco> { TPoco Create(); } interface IDeletable<TPoco> { bool Delete(TPoco item); } interface IRetrievable<TKey, TPoco> { TPoco Retrieve(TKey input); } } This sample program represents the interfaces my actual program uses, and demonstrates the problem I'm having (commented out in FakeRepository). I would like for this method call to be generically handled by the base class (which in my real example is able to handle 95% of the cases given to it), allowing for overrides in the child classes by specifying the type of TKey explicitly. It doesn't seem to matter what parameter constraints I use for the IRetrievable, I can never get the method call to fall through to the base class. Also, if anyone can see an alternate way to implement this kind of behavior and get the result I'm ultimately looking for, I would be very interested to see it. Thoughts?

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• android: ending activity from tab

  - by Jin

  I have 3 classes, let's call them 1, 2, and 3. Class 1 extends TabActivity and organizes the whole tab thing, Class 2 and 3 are just two separate tabs each with some lines of text. I call Class 1 from another activity using startActivityForResult. I then added an optionsMenu in class 2, and when user clicks the optionMenu, the following code is carried out: @Override public boolean onMenuItemSelected(int featureId, MenuItem item) { Intent i = new Intent(); switch(item.getItemId()) { case Result.NEXT_ID: i.putExtra(Result.PAGE_REQUEST, NEXT); setResult(RESULT_OK, i); finish(); break; case Result.PREV_ID: i.putExtra(Result.PAGE_REQUEST, PREV); setResult(RESULT_OK, i); finish(); } return super.onMenuItemSelected(featureId, item); } In my parent class (the class that called 1 to begin with), in its onActivityResult function, I want to get the data from the extras. However, the intent is always null, and I can't figure out why. When I call finish() on class 2, is it calling some other function in class 1? Do I have to transfer the intent data somehow?

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• Dynamic Array of Objects Sans Vector Class

  - by Connor Black

  I am doing a homework assignment for my summer OO class and we need to write two classes. One is called Sale and the other is called Register. I've written my Sale class; here's the .h file: enum ItemType {BOOK, DVD, SOFTWARE, CREDIT}; class Sale { public: Sale(); // default constructor, // sets numerical member data to 0 void MakeSale(ItemType x, double amt); ItemType Item(); // Returns the type of item in the sale double Price(); // Returns the price of the sale double Tax(); // Returns the amount of tax on the sale double Total(); // Returns the total price of the sale void Display(); // outputs sale info private: double price; // price of item or amount of credit double tax; // amount of sales tax double total; // final price once tax is added in. ItemType item; // transaction type }; For the Register class we need to include a dynamic array of Sale objects in our member data. We cannot use the vector class. How is this done? Here's my 'Register' '.h' class Register{ public: Register(int ident, int amount); ~Register(); int GetID(){return identification;} int GetAmount(){return amountMoney;} void RingUpSale(ItemType item, int basePrice); void ShowLast(); void ShowAll(); void Cancel(); int SalesTax(int n); private: int identification; int amountMoney; };

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• Need an advice for ASP.NET MVC2 Newsletter Project

  - by ck3g

  I'm new in ASP.NET MVC2. But I want to develop a simply Newsletter site. The main problem which stuck me is how correctly use MVC pattern in News details and comments list. For example: I have a NewsController and action Details inside. And two model classes News and Comments. I want show all comments belongs to this News record and textarea for adding new comments. I wand display all this content in /News/Details/ How can i do it? I tried use PartialViews in Details View: one for Adding Comment and another for Comment list. I have passed comment object thorough ViewData["Comment"]. But i have problems with my models (think I cant use two models in View) Again. How can I display Single Post + Comments + add comment view at single page using ASP.NET MVC2? Another Example is stackoverflow.com. Here is an question + answers + write answer. I need same structure

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• When to use basic types (Integer, String), and when to write a new class?

  - by belgarat

  Stackoverflow users: A lot of things can be represented in programs by using the basic types, or we can create a new class for it. Example: A social security number can be a number, string or its own object. (Other common examples: Phone numbers, names, zip codes, user id, order id and other id's.) My question is: When should the basic types be used, and when should we write ourselves a new class? I see that when you need to add behavior, you'll want to create a class (example, social security number parsing, validation, formatting, etc). But is this the only criteria? I have come across cases where many of these things are represented as java Integers and/or Strings. We loose the benefit of type-checking, and I have often seen bugs caused by parameters being mixed in calls to function(Intever, Integer, Integer, Integer). On the other hand, some programmers are opposed to over-designing by creating classes for "eveything". Obviously, the answer is "it depends". But, what do you think, and what do you normally do?

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• Why does the VS2005 debugger not report "base." values properly? (was "Why is this if statement fail

  - by Rawling

  I'm working on an existing class that is two steps derived from System.Windows.Forms.Combo box. The class overrides the Text property thus: public override string Text { get { return this.AccessibilityObject.Value; } set { if (base.Text != value) { base.Text = value; } } } The reason given for that "get" is this MS bug: http://support.microsoft.com/kb/814346 However, I'm more interested in the fact that the "if" doesn't work. There are times where "base.Text != value" is true and yet pressing F10 steps straight to the closing } of the "set" and the Text property is not changed. I've seen this both by just checking values in the debugger, and putting a conditional breakpoint on that only breaks when the "if" statement's predicate is true. How on earth can "if" go wrong? The class between this and ComboBox doesn't touch the Text property. The bug above shouldn't really be affecting anything - it says it's fixed in VS2005. Is the debugger showing different values than the program itself sees? Update I think I've found what is happening here. The debugger is reporting value incorrectly (including evaluating conditional breakpoints incorrectly). To see this, try the following pair of classes: class MyBase { virtual public string Text { get { return "BaseText"; } } } class MyDerived : MyBase { public override string Text { get { string test = base.Text; return "DerivedText"; } } } Put a breakpoint on the last return statement, then run the code and access that property. In my VS2005, hovering over base.Text gives the value "DerivedText", but the variable test has been correctly set to "BaseText". So, new question: why does the debugger not handle base properly, and how can I get it to?

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• Fluent NHibernate no data being returned

  - by czuroski

  Hello, I have been successfully using NHibernate, but now I am trying to move to Fluent NHibernate. I have created all of my mapping files and set up my session manager to use a Fluent Configuration. I then run my application and it runs successfully, but no data is returned. There are no errors or any indication that there is a problem, but nothing runs. when using NHibernate, if I don't set my hbm xml files as an embedded resource, this same thing happens. This makes me wonder what I have to set my Map classes to. Right now, they are just set to Compile, and they are compiled into the dll, which I can see by disassembling it. Does anyone have any thoughts as to what may be happening here? Thanks private ISessionFactory GetSessionFactory() { return Fluently.Configure() .Database( IfxOdbcConfiguration .Informix1000 .ConnectionString("Provider=Ifxoledbc.2;Password=mypass;Persist Security Info=True;User ID=myuser;Data Source=mysource") .Dialect<InformixDialect1000>() .ProxyFactoryFactory<ProxyFactoryFactory>() .Driver<OleDbDriver>() .ShowSql() ) .Mappings( m => m.FluentMappings .AddFromAssemblyOf<cmCase>() .AddFromAssemblyOf<attorney>() .AddFromAssemblyOf<creditor>() .AddFromAssemblyOf<party>() .AddFromAssemblyOf<person>() .AddFromAssemblyOf<sardbk>() .AddFromAssemblyOf<schedule>() //x => x.FluentMappings.AddFromAssembly(System.Reflection.Assembly.GetExecutingAssembly()) //.ExportTo("C:\\mappings") ) .BuildSessionFactory(); }

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• What is a better, cleaner way of using List<T>

  - by Tim Meers

  I'm looking to implement a few nicer ways to use List in a couple of apps I'm working on. My current implementation looks like this. MyPage.aspx.cs protected void Page_Load(object sender, EventArgs e) { BLL.PostCollection oPost = new BLL.PostCollection(); oPost.OpenRecent(); rptPosts.DataSource = oArt; rptPosts.DataBind(); } BLL Class(s) public class Post { public int PostId { get; set; } public string PostTitle { get; set; } public string PostContent { get; set; } public string PostCreatedDate { get; set; } public void OpenRecentInitFromRow(DataRow row) { this.PostId = (int) row["id"]; this.PostTitle = (string) row["title"]; this.PostContent = (string) row["content"]; this.PostCreatedDate = (DateTime) row["createddate"]; } } public class PostCollection : List<Post> { public void OpenRecent() { DataSet ds = DbProvider.Instance().Post_ListRecent(); foreach (DataRow row in ds.Tables[0].Rows) { Post oPost = new Post(); oPost.OpenRecentInitFromRow(row); Add(oPost); } } } Now while this is working all well and good, I'm just wondering if there is any way to improve it, and just make it cleaner that having to use the two different classes do to something I think can happen in just one class or using an interface.

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• Is this a good way to generically deserialize objects?

  - by Damien Wildfire

  I have a stream onto which serialized objects representing messages are dumped periodically. The objects are one of a very limited number of types, and other than the actual sequence of bytes that arrives, I have no way of knowing what type of message it is. I would like to simply try to deserialize it as an object of a particular type, and if an exception is thrown, try again with the next type. I have an interface that looks like this: public interface IMessageHandler<T> where T : class, IMessage { T Handle(string message); } // elsewhere: // (These are all xsd.exe-generated classes from an XML schema.) public class AppleMessage : IMessage { ... } public class BananaMessage : IMessage { ... } public class CoconutMessage : IMessage { ... } Then I wrote a GenericHandler<T> that looks like this: public class GenericHandler<T> : IMessageHandler<T> where T: class, IMessage { public class MessageHandler : IMessageHandler { T IMessageHandler.Handle(string message) { T result = default(T); try { // This utility method tries to deserialize the object with an // XmlSerializer as if it were an object of type T. result = Utils.SerializationHelper.Deserialize<T>(message); } catch (InvalidCastException e) { result = default(T); } return result; } } } Two questions: Using my GenericHandler<T> (or something similar to it), I'd now like to populate a collection with handlers that each handle a different type. Then I want to invoke each handler's Handle method on a particular message to see if it can be deserialized. If I get a null result, move onto the next handler; otherwise, the message has been deserialized. Can this be done? Is there a better way to deserialize data of unknown (but restricted) type?

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• height autoflow autofill into out div

  - by Brian Putt

  I have a fiddle(http://jsfiddle.net/pwnagecss/LnNYv/) and need help in making it so the classes sideBar, and rightContentWrapper autofill to the height. <div class="wrapper"> <div class="sideBar"> </div> <div class="rightContentWrapper"> <div class="rightContent"> </div> </div> </div> .wrapper { width: 960px; height: 100%; margin: 0 auto 20px auto; padding: 0; background-color:black; } .wrapper:after{ clear: both; display: block; height: 0; visibility: hidden; content: "0020"; } .sideBar { float: left; width: 200px; background-color:blue; min-height: inherit; height: 100%; } .rightContentWrapper { float: left; width: 760px; height: 100%; min-height: inherit; } .rightContent { margin: 0 auto; background-color: red; min-height: inherit; } Any help is appreciated

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• ASP.NET Grid with CSS in Rows and Columns

  - by user1089173

  I have the following code List<Department> depts = new List<Department>(); Department.Add(new Department() { DNo = 1, DName = "Accounting", DFloor="6" }); Department.Add(new Department() { DNo = 2, DName = "FInance", DFloor="3" }); I want to bind this data to a GridView, so that it outputs the following. Observe the classes on each th and tr. How can I achieve this in ASP.NET? <thead> <tr> <th class="DNo">DNo</th> <th class="DName">DName</th> <th class= "DFloor">DFloor</th> </tr> </thead> <tr> <td class="DNo">1</td> <td class="DName">Accounting</td> <td class="DFloor">6</td> </tr> <tr> <td class="DNo">2</td> <td class="DName">FInance</td> <td class="DFloor">3</td> </tr>

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• PC to Macbook Pro Transition - Getting (re)started?

  - by Torus Linvald

  I'm in my second computer science course right now. I've enjoyed programming so far, but really have just scraped my way by. I've not done much programming outside of required class work. For similar reasons, I never really invested in downloading/learning software to help me program (IDE's, editors, compilers, etc). I know it sounds tedious, but my current setup is: notepad++ for coding; Filezilla to transfer .cpp & .h files to school's aludra/unix and compiling; unix tells me where my bugs are and I go back to notepad++ to debug; repeat until done. This isn't fun - and I know it could be easier. But I put it off knowing that I was soon going to switch to a Mac. And, tomorrow, I'm switching. So... How should I set up my Macbook for the best programming experience? What IDEs and editors and debuggers and so on should I download? How will Mac programming differ from PC? I'm open to all ideas and comments, even the most basic. (Background - I'm learning/programming in C++ right now. Next semester, my classes switch to Java. I'm also going to take a class in web development, with HTML/CSS/Javascript/PHP. My new laptop will be a late 2009 Macbook Pro with Leopard, or maybe Snow Leopard. Free would be preferrable for all programs.) Thank you all.

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• What is the Rule of Thumb on Exposing Encapsulated Class Methods

  - by javamonkey79

  Consider the following analogy: If we have a class: "Car" we might expect it to have an instance of "Engine" in it. As in: "The car HAS-A engine". Similarly, in the "Engine" class we would expect an instance of "Starting System" or "Cooling System" which each have their appropriate sub-components. By the nature of encapsulation, is it not true that the car "HAS-A" "radiator hose" in it as well as the engine? Therefore, is it appropriate OO to do something like this: public class Car { private Engine _engine; public Engine getEngine() { return _engine; } // is it ok to use 'convenience' methods of inner classes? // are the following 2 methods "wrong" from an OO point of view? public RadiatorHose getRadiatorHose() { return getCoolingSystem().getRadiatorHose(); } public CoolingSystem getCoolingSystem() { return _engine.getCoolingSystem(); } } public class Engine { private CoolingSystem _coolingSystem; public CoolingSystem getCoolingSystem() { return _coolingSystem; } } public class CoolingSystem { private RadiatorHose _radiatorHose; public RadiatorHose getRadiatorHose() { return _radiatorHose; } } public class RadiatorHose {//... }

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• Creating the same event for 2 different elements in jQuery (not for each one, for both!)

  - by danfromisrael

  Hey guys, I'd like to create a toggle event for 2 different TD's in my table row. the event should show / hide the next table row. <table> <tr> <td>1</td> <td>2</td> <td>3</td> <td>4</td> <td>5</td> <td class="clickable1">6</td> <td class="clickable2">7</td> </tr> <tr><td>this row should be toggled between show/hide once one of the clickable TDs were clicked</td></tr> </table> here's the code i tried to apply but it has applied each one of the classes the event: $('.clickable1,.clickable2').toggle(function() { $(this).parent() .next('tr') .show(); }, function() { $(this).parent() .next('tr') .hide(); }); One more thing: i'm applying on each TR a css hover psuedo class. how can i make the two TRs to be highlighted (like hover effect on two of them) ? Thanks in advanced! :-Dan

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• Beginner Question ; About Prime Generation in "C" - What is wrong with my code ? -

  - by alorsoncode

  I'm a third year irregular CS student and ,i just realized that i have to start coding. I passed my coding classes with lower bound grades so that i haven't a good background in coding&programming. I'm trying to write a code that generates prime numbers between given upper and lower bounds. Not knowing C well, enforce me to write a rough code then go over it to solve. I can easily set up the logic for intended function but i probably create a wrong algorithm through several different ways. Here I share my last code, i intend to calculate that when a number gives remainder Zero , it should be it self and 1 , so that count==2; What is wrong with my implementation and with my solution generating style? I hope you will warm me up to programming world, i couldn't find enough motivation and courage to get deep into programming. Thanks in Advance :) Stdio and Math.h is Included int primegen(int down,int up) { int divisor,candidate,count=0,k; for(candidate=down;candidate<=up;candidate++) { for(divisor=1;divisor<=candidate;divisor++) { k=(candidate%divisor); } if (k==0) count++; if(count==2) { printf("%d\n", candidate); count=0; } else { continue; } } } int main() { primegen(3,15); return 0; }

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• when to use Hibernate vs. Simple ResultSets for small application

  - by luke

  I just started working on upgrading a small component in a distributed java application. The main application is a rather complicated applet/servlet combo running on JBoss and it extensively uses Hibernate for its DataAccess. The component i am working on however is very a very straightforward data importing service. Basically the workflow is Listen for a network event Parse the data packet, extract a set of identifiers Map the identifier set to a primary key in our database Parse the rest of the packet and insert items in a related table using the foreign key found in step 3 Repeat in the previous version of this component it used a hibernate based DAL, that is no longer usable for a variety of reasons (in particular it is EOL), so I am in charge of replacing the Data Access layer for this component. So on the one hand I think i should use Hibernate because that's what the rest of the application does, but on the other i think i should just use regular java.sql.* classes because my requirements are really straightforward and aren't expected to change any time soon. So my question is (and i understand it is subjective) at what point do you think that the added complexity of using an ORM tool (in terms of configuration, dependencies...) is worth it? UPDATE due to the way the DataAccesLayer for the main application was written (weird dependencies) i cannot easily use it, i would have to implement it myself.

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• How to use the Zend_Log instance that was created using the Zend_Application_Resource_Log in a model

  - by Alex

  Our Zend_Log is initialized by only adding the following lines to application.ini resources.log.stream.writerName = "Stream" resources.log.stream.writerParams.mode = "a" So Zend_Application_Resource_Log will create the instance for us. We are already able to access this instance in controllers via the following: public function getLog() { $bootstrap = $this->getInvokeArg('bootstrap'); //if (is_null($bootstrap)) return false; if (!$bootstrap->hasPluginResource('Log')) { return false; } $log = $bootstrap->getResource('Log'); return $log; } So far, so good. Now we want to use the same log instance in model classes, where we can not access the bootstrap. Our first idea was to register the very same Log instance in Zend_Registry to be able to use Zend_Registry::get('Zend_Log') everywhere we want: in our Bootstrap class: protected function _initLog() { if (!$this->hasPluginResource('Log')) { throw new Zend_Exception('Log not enabled'); } $log = $this->getResource('Log'); assert( $log != null); Zend_Registry::set('Zend_Log', $log); } Unfortunately this assertion fails == $log IS NULL --- but why?? It is clear that we could just initialize the Zend_Log manually during bootstrapping without using the automatism of Zend_Application_Resource_Log, so this kind of answers will not be accepted.

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• [Rails3] How to do multiple many to many relationships between the same two tables.

  - by Kurt

  Hi. I have a model of a club where I want to model the two entities Meeting and Member. There are actually two many-to-many relationships between these entities though, as for any meeting a Member can either be a Speaker or a Guest. Now I am an OO thinker, so would normally just create the two classes and each one would just have two arrays of the other inside, but rails is making me think a bit more data centric here, so I realise I need to break these M2M relationships up with join tables Speakers and Guests which I have done, but now I am having trouble describing the relationships in the models. The two join table models both have "belongs_to :meeting" and "belongs_to :member" and I think that should be sufficient. I am not however sure about the Meeting and Member models though. Each one has "has_many :guests" and "has_many: speakers" but I am not sure if I also want to go: has_many :members, :through = :guests has_many :members, :through = :speakers But I suspect that this is like declaring two "members" that will clash. I also thought about: has_many :guests, :through = :guests has_many :speakers, :through = :speakers Does that make sense? How would ActiveRecord know that they are in fact Members? I have found heaps of examples of polymorphic m2m relationships and m2m relationships where 1 table references itself, but no good examples to help me mode this situation where two separate tables have two different m2m relationships. Anyone got any tips?

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• Scope of Groovy's ExpandoMetaClass?

  - by TicketMonster

  Groovy exposes an ExpandoMetaClass that allows you to dynamically add instance and class methods/properties to a POJO. I would like to use it to add an instance method to one of my Java classes: public class Fizz { // ...etc. } Fizz fizz = new Fizz(); fizz.metaClass.doStuff = { String blah -> fizz.buzz(blah) } This would be the equivalent to refactoring the Fizz class to have: public class Fizz { // ctors, getters/setters, etc... public void doStuff(String blah) { buzz(blah); } } My question: Does this add doStuff(String blah) to only this particular instance of Fizz? Or do all instances of Fizz now have a doStuff(String blah) instance method? If the former, how do I get all instances of Fizz to have the doStuff instance method? I know that if I made the Groovy: fizz.metaClass.doStuff << { String blah -> fizz.buzz(blah) } Then that would add a static class method to Fizz, such as Fizz.doStuff(String blah), but that's not what I want. I just want all instances of Fizz to now have an instance method called doStuff. Ideas?

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• Java: How ArrayList memory management

  - by cka3o4nik

  In my Data Structures class we have studies the Java ArrayList class, and how it grows the underlying array when a user adds more elements. That is understood. However, I cannot figure out how exactly this class frees up memory when lots of elements are removed from the list. Looking at the source, there are three methods that remove elements: [code] public E remove(int index) { RangeCheck(index); modCount++; E oldValue = (E) elementData[index]; int numMoved = size - index - 1; if (numMoved 0) System.arraycopy(elementData, index+1, elementData, index, numMoved); elementData[--size] = null; // Let gc do its work return oldValue; } public boolean remove(Object o) { if (o == null) { for (int index = 0; index < size; index++) if (elementData[index] == null) { fastRemove(index); return true; } } else { for (int index = 0; index < size; index++) if (o.equals(elementData[index])) { fastRemove(index); return true; } } return false; } private void fastRemove(int index) { modCount++; int numMoved = size - index - 1; if (numMoved 0) System.arraycopy(elementData, index+1, elementData, index, numMoved); elementData[--size] = null; // Let gc do its work } {/code] None of them reduce the datastore array. I even started questioning if memory free up ever happens, but empirical tests show that it does. So there must be some other way it is done, but where and how? I checked the parent classes as well with no success.

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• Experiences wanted: producing a jar artifact in IntelliJ

  - by skiaddict1

  Developing with IntelliJ 9.0.2 Community Edition, on the Mac. This is a follow-up to this post about including jar files in an artifact, which has not received any replies. I'm hoping that the reason is that somehow, in creating my artifact (or setting my project settings), I unwittingly did something which people don't tend to do, and which is causing my problem, and that by asking people here to share how they create jar artifacts and set up projects, I will discover what it is. To recap: I have a Java project which depends on two library files. I need to package up the entire thing, with the jars inlined (such that on doing jar -tfv <filename> I see ALL the classes listed, including the ones in the two libraries), into a single jar file. I can make an artifact, I can add the library files to the Output Layout pane, but I CANNOT, no matter what I do, I cannot get the "Inline Artifact" item in the context menu to be selectable (i.e. non-grey) when I right-click on one or other library file. The thing is, making a jar which contains library files as well as the project code is NOT an unusual situation in the Java world! So I figure there are lots of IntelliJ folks out there who have done what I need to do. And I would really like to hear from you folks. What project settings do you use? (be specific, please :-) And exactly how do you set up your jar artifacts? (again, as many specific details as possible, please :-) Clearly, I'd be particularly interested to hear from folks with similar setups to mine (above) who are successfully doing what I need to do. Grateful thanks in advance, folks.

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