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  • Referencing not-yet-defined variables - Java

    - by user2537337
    Because I'm tired of solving math problems, I decided to try something more engaging with my very rusty (and even without the rust, very basic) Java skills. I landed on a super-simple people simulator, and thus far have been having a grand time working through the various steps of getting it to function. Currently, it generates an array of people-class objects and runs a for loop to cycle through a set of actions that alter the relationships between them, which I have stored in a 2d integer array. When it ends, I go look at how much they all hate each other. Fun stuff. Trouble has arisen, however, because I would like the program to clearly print what action is happening when it happens. I thought the best way to do this would be to add a string, description, to my "action" class (which stores variables for the actor, reactor, and the amount the relationship changes). This works to a degree, in that I can print a generic message ("A fight has occurred!") with no problem. However, ideally I would like it to be a little more specific ("Person A has thrown a rock at Person B's head!"). This latter goal is proving more difficult: attempting to construct an action with a description string that references actor and reactor gets me a big old error, "Cannot reference field before it is defined." Which makes perfect sense. I believe I'm not quite in programmer mode, because the only other way I can think to do this is an unwieldy switch statement that negates the need for each action to have its own nicely-packaged description. And there must be a neater way. I am not looking for examples of code, only a push in the direction of the right concept to handle this.

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  • Best method to select an object from another unknown jQuery object

    - by Yosi
    Lets say I have a jQuery object/collection stored in a variable named obj, which should contain a DOM element with an id named target. I don't know in advance if target will be a child in obj, i.e.: obj = $('<div id="parent"><div id="target"></div></div>'); or if obj equals target, i.e.: obj = $('<div id="target"></div>'); or if target is a top-level element inside obj, i.e.: obj = $('<div id="target"/><span id="other"/>'); I need a way to select target from obj, but I don't know in advance when to use .find and when to use .filter. What would be the fastest and/or most concise method of extracting target from obj? What I've come up with is: var $target = obj.find("#target").add(obj.filter("#target")); UPDATE I'm adding solutions to a JSPERF test page to see which one is the best. Currently my solution is still the fastest. Here is the link, please run the tests so that we'll have more data: http://jsperf.com/jquery-selecting-objects

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  • Whose fault is a NullReferenceException?

    - by stefan.at.wpf
    I'm currently working on a class which exposes an internal List through a property. The List shall and can be modified. The problem is, entries in the internal list could be set to null from outside the class. My code actually looks like this: class ClassWithList { List<object> _list = new List<object>(); // get accessor, which however returns the reference to the list, // therefore the list can be modified (this is intended) public List<object> Data { get { return _list; } } private void doSomeWorkWithTheList() { foreach(object obj in _list) // do some work with the objects in the list without checking for null. } } So now in the doSomeWorkWithTheList() I could always check whether the current list entry is null or I could just asume that the person using this class doesn't have the great idea to set entries to null. So finally the questions end up in: Whose fault is a NullReferenceException in this case? Is it the fault of the class developer not checking everything for null (which would make code generally - not only in this class - more complex) or is it the fault of the user of this class, as setting a List entry to null doesn't really make sense? I'd tend to generally not check values for null except in some really special cases. Is this a bad style or de facto standard / standard in praxis? I know there's probably no ultimate answer for this, I'm just missing enough experience for such thing and therefore wondering what other developers think about such cases and want to hear what's done in reality about checking null (or not).

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  • java: libraries for immutable functional-style data structures

    - by Jason S
    This is very similar to another question (Functional Data Structures in Java) but the answers there are not particularly useful. I need to use immutable versions of the standard Java collections (e.g. HashMap / TreeMap / ArrayList / LinkedList / HashSet / TreeSet). By "immutable" I mean immutable in the functional sense (e.g. purely functional data structures), where updating operations on the data structure do not change the original data, but instead return a new instance of the same kind of data structure. Also typically new and old instances of the data structure will share immutable data to be efficient in time and space. From what I can tell my options include: Functional Java Scala Clojure but I'm not sure whether any of these are particularly appealing to me. I have a few requirements/desirements: the collections in question should be usable directly in Java (with the appropriate libraries in the classpath). FJ would work for me; I'm not sure if I can use Scala's or Clojure's data structures in Java w/o having to use the compilers/interpreters from those languages and w/o having to write Scala or Clojure code. Core operations on lists/maps/sets should be possible w/o having to create function objects with confusing syntaxes (FJ looks slightly iffy) They should be efficient in time and space. I'm looking for a library which ideally has done some performance testing. FJ's TreeMap is based on a red-black tree, not sure how that rates. Documentation / tutorials should be good enough so someone can get started quickly using the data structures. FJ fails on that front. Any suggestions?

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  • ios UITableView reloadData don't increase content height

    - by Zoltan Varadi
    I'm facing a strange error in my iOS app and haven't been able to figure out the reason why. In my UITableView i can add new cells, so i refresh the array that is the datasource and call reloadData. Everything works without error. The numberOfRowsInSection is called again, and it's value is one more than it's previous value was. The new cell even gets inserted at the bottom of the tableview, but i cant scroll down to it. I only know that it's there because the tableview bounces and i can see it. I'm guessing the tableview's content height is not getting increased for some reason, but i have no idea why. I'm using iOS 6 btw. Any help is very much appreciated! Thanks, Zoli EDIT, answers for Srikanth's questions: How is data getting added. There's an NSArray containing objects of a specific type. The array.count is the number of the number of cells. This NSArray gets its values from a database query. When you say, you are refreshing the array, what do you mean. By refreshing the array i mean i execute a new query in the database and put the results of this query into an NSArray. this will be the tableview's datasource array. Like this: dataSourceArray = [dbManager executeQuery]; [tableView reloadData]; Are you adding the data within the same view controller Yes. Can you show some code as to what you are doing See above. Is the table view at the root of the view controllers view or is it within another view The tableview is the main view's first child. Can you try adding data to the array at the beginning, so that you can view the cell being added at the top. I don't understand what you mean.

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  • MVC and jQuery data retrieval.

    - by user337542
    Hello, I am using mvc and jQuery and I am trying to display someone's profile with some additional institutions that the person belongs to. I am new to this but I've done something like this in ProfileControler: public ActionResult Institutions(int id) { var inst = fr.getInstitutions(id); return Json(inst); } getInstitutions(id) returns Institution objects(with Name, City, Post Code etc.) Then in a certain View I am trying to get the data with jQuery and display them as follows: $(document).ready(function () { $.post("/Profile/Institutions", { id: <%= Model.Profile.userProfileID %> }, function (data) { $.each(data, function () { var new_div = $("<div>"); var new_label = $("<label>"); new_label.html(this.City); var new_input_b = $("<input>"); new_input_b.attr("type", "button"); new_div.append(new_label); new_div.append(new_input_b); $("#institutions").append(new_div); }); }); }); $("#institutions") is a div where i want to display all of the results. .post works correct for sure because certain institutions are retrieved from database, and passed to the view as Json result. But then I am affraid it wont itterate with .each. Any help, coments or pointing in some direction would be much appriciated

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  • Are there equivalents to Ruby's method_missing in other languages?

    - by Justin Ethier
    In Ruby, objects have a handy method called method_missing which allows one to handle method calls for methods that have not even been (explicitly) defined: Invoked by Ruby when obj is sent a message it cannot handle. symbol is the symbol for the method called, and args are any arguments that were passed to it. By default, the interpreter raises an error when this method is called. However, it is possible to override the method to provide more dynamic behavior. The example below creates a class Roman, which responds to methods with names consisting of roman numerals, returning the corresponding integer values. class Roman def romanToInt(str) # ... end def method_missing(methId) str = methId.id2name romanToInt(str) end end r = Roman.new r.iv #=> 4 r.xxiii #=> 23 r.mm #=> 2000 For example, Ruby on Rails uses this to allow calls to methods such as find_by_my_column_name. My question is, what other languages support an equivalent to method_missing, and how do you implement the equivalent in your code?

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  • What is the purpose of unit testing an interface repository

    - by ahsteele
    I am unit testing an ICustomerRepository interface used for retrieving objects of type Customer. As a unit test what value am I gaining by testing the ICustomerRepository in this manner? Under what conditions would the below test fail? For tests of this nature is it advisable to do tests that I know should fail? i.e. look for id 4 when I know I've only placed 5 in the repository I am probably missing something obvious but it seems the integration tests of the class that implements ICustomerRepository will be of more value. [TestClass] public class CustomerTests : TestClassBase { private Customer SetUpCustomerForRepository() { return new Customer() { CustId = 5, DifId = "55", CustLookupName = "The Dude", LoginList = new[] { new Login { LoginCustId = 5, LoginName = "tdude" }, new Login { LoginCustId = 5, LoginName = "tdude2" } } }; } [TestMethod] public void CanGetCustomerById() { // arrange var customer = SetUpCustomerForRepository(); var repository = Stub<ICustomerRepository>(); // act repository.Stub(rep => rep.GetById(5)).Return(customer); // assert Assert.AreEqual(customer, repository.GetById(5)); } } Test Base Class public class TestClassBase { protected T Stub<T>() where T : class { return MockRepository.GenerateStub<T>(); } } ICustomerRepository and IRepository public interface ICustomerRepository : IRepository<Customer> { IList<Customer> FindCustomers(string q); Customer GetCustomerByDifID(string difId); Customer GetCustomerByLogin(string loginName); } public interface IRepository<T> { void Save(T entity); void Save(List<T> entity); bool Save(T entity, out string message); void Delete(T entity); T GetById(int id); ICollection<T> FindAll(); }

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  • How do I make custom functions chain-able with jQuery's?

    - by sergio
    I need a "callfront" or "precall" (the opposite of "callback" ¿?) to add in MANY places before an animation occurs in an existing plugin, To be used like e.g. $(some_unpredictable_obj).preFunct().animate(… The problem is, as I said they are MANY places, and all of them are different animations, on different objects. I can TELL where all of them occur, but I don't want to add over and over the same code. I actually have to add both a function before and after those animations, but I think I can use the callback for all of them. In a perfect world, I'd like to replace every animate(property, duration) by preFunct().animate(property,duration).postFunct() preFunct and postFunct don't need parameters, since they are always the same action, on the same object. This could be an amazing addition to "jQuery" (an easy way to jQuerize custom functions to be added to the normal chain (without messing with queues) I found this example but it will act on the applied element, and I don't want that because, as I said above, all the original animations to be added to are on different elements. I also found jQuery.timing, but it looks cooler the chain-able function :) Thanks.

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  • Is it possible, in a django template, to check if an object is contained in a list

    - by AlexH
    I'm very new to django, about a week into it. I'm making a site where users enter stuff, then other users can vote on whether they like the stuff or not. I know it's not so novel, but it's a good project to learn a bunch of tools. I have a many-to-many table for storing who likes or dislikes what. Before I render the page, I pull out all the likes and dislikes for the current user, along with the stuff I'm going to show on the page. When I render the page, I go through the list of stuff I'm going to show and print them out one at a time. I want to show the user which stuff they liked, and which they didn't. So in my django template, I have an object called entry. I also have two lists of objects called likes and dislikes. Is there any way to determine if entry is a member of either list, inside my django template. I think what I'm looking for is a filter where I can say something like {% if entry|in:likes %} or {% if likes|contains:entry %} I know I could add a method to my model and check for each entry individually, but that seems like it would be database intensive. Is there a better way to think about this problem?

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  • How can I invoke a .Net DLL from a LabView 6.1 VI?

    - by tw1k
    I work in a manufacturing company that uses LabView for testing the devices we make. Most of the test engineers are using 7.1 which can natively reference a .Net assembly. However, there is a group that is stuck on LabView 6.1. I would like for them to be able to use my .Net assembly which is basically a proxy to some web services. I have created a test assembly that is nothing more than Hello World, and I'm trying to consume it in a VI. I made it COM visible, and registered it with regasm.exe and created a type library, which I'm not sure I need. I can see it in Visual Studio in the list of COM objects when I open the Add Reference window, so I know it's registered properly. I'm very unfamiliar with VI's. I'm only looking at it because no one I have spoken to in manufacturing knows anything about invoking a COM object in a VI. I'm basically looking for some names of controls or menu options to get the test engineers pointed in the right direction. I did a bunch of web searching on Google and the NI forums, but didn't find much. Alternatively, would it be easier to write a C or C++ DLL that acts as a proxy to my .Net DLL? Or is there a simple way to invoke a web service from a VI? That might obviate the need for a DLL altogether. I'm currently reading through this document from NI for help, but it obviously knows nothing about .Net and might not be able to help me choose the best path forward.

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  • how to make accessor for Dictionary in a way that returned Dictionary cannot be changed C# / 2.0

    - by matti
    I thought of solution below because the collection is very very small. But what if it was big? private Dictionary<string, OfTable> _folderData = new Dictionary<string, OfTable>(); public Dictionary<string, OfTable> FolderData { get { return new Dictionary<string,OfTable>(_folderData); } } With List you can make: public class MyClass { private List<int> _items = new List<int>(); public IList<int> Items { get { return _items.AsReadOnly(); } } } That would be nice! Thanks in advance, Cheers & BR - Matti NOW WHEN I THINK THE OBJECTS IN COLLECTION ARE IN HEAP. SO MY SOLUTION DOES NOT PREVENT THE CALLER TO MODIFY THEM!!! CAUSE BOTH Dictionary s CONTAIN REFERENCES TO SAME OBJECT. DOES THIS APPLY TO List EXAMPLE ABOVE? class OfTable { private string _wTableName; private int _table; private List<int> _classes; private string _label; public OfTable() { _classes = new List<int>(); } public int Table { get { return _table; } set { _table = value; } } public List<int> Classes { get { return _classes; } set { _classes = value; } } public string Label { get { return _label; } set { _label = value; } } } so how to make this immutable??

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  • Some questions about the .NET Entity Framework and Stored Procedures

    - by Bara
    Hey everyone, I had a couple of questions relating to the .NET Entity Framework and using stored procedures. Here goes: I know that we can right click a stored procedure and choose Function Import to be able to use with code. Is there a way to do this for many stored procedures at once? When doing a Function Import, I can create a new Complex type or use an existing Complex type. Well, how can I access Complex types/objects that are outside of the edmx file? That is, if I have a class in my project, is it possible to access it while doing a Function Import? When calling the stored procedure from code, it returns an IEnumerable of the Complex type I set it as. However, sometimes these complex types do not have all of the properties that I need, so I create a new class in my project that inherits from the complex type used in the stored procedure. Problem is, I can't seem to cast the complex type returned from the stored procedure to the new class I created. Any reason why I can't do this? What I ended up doing is looping through the IEnumerable and adding each item to a new list of the class that I created. But this feels and looks messy. Bara

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  • NHibernate mapping with two special cases

    - by brainimus
    I am using NHibernate to map a class to a database table. The Part table has an ID column (primary key) and a ParentPart column (along with a few others). class Part { public virtual long ID{ get; set; } public virtual Part ParentPart { get; set; } } The ParentPart is normally another valid part in the part table but I have two special cases. I have a case where the ParentPart column can be 0 (zero) and another case where it can be -1. Neither of these cases currently represent another valid Part object. I was thinking I could make 2 subclasses of Part (ZeroPart and NegativeOnePart) that would never persist. I want the zero and -1 values to be entered in the column but not persist the entire ZeroPart or NegativeOnePart objects. I am unsure how to map this (I'm using hbm files) or if this even the correct approach. How can I map this so that normal valid parts are persisted but I can also handle the special cases? As an aside: My current hbm file has the Part.ID's unsaved value as zero but I think I can just change this in the mapping to something different and default it in the class.

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  • How big can I make an Android application's canvas in terms of pixels?

    - by user279112
    I've determined an estimate of the size of my Android emulator's screen in pixels, although I think its resolution can be changed to other numbers. Quite frankly though that doesn't eliminate the general problem of not knowing how many pixels on each axis I have to work with on my Android applications in general. The main problem I'm trying to solve is this: How do I make sure I don't use a faulty resolution on Android applications if I want to keep things' sizes constant (so that if the application screen shrinks, for instances, objects will still show up just as big - there just won't be as many of them being shown) if I wish to do this with a single universal resolution for each program? Failing that, how do I make sure everything's alright if I try to do everything the same way with maybe a few different pre-set resolutions? Mainly it seems like a relevant question that must be answered before I can come across a complete answer for the general problem is how big can I always make my application in pixels, NOT regarding if and when a user resizes the application's screen to something smaller than the maximum size permitted by the phone and its operating system. I really want to try to keep this simple. If I were doing this for a modern desktop, for instance, I know that if I design the application with a 800x600 canvas, the user can still shrink the application to the point they're not doing themselves any favors, but at least I can basically count on it working right and not being too big for the monitor or something. Is there such a magic resolution for Android, assuming that I'm designing for API levels 3+ (Android 1.5+)? Thanks

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  • Alternatives to static methods on interfaces for enforcing consistency

    - by jayshao
    In Java, I'd like to be able to define marker interfaces, that forced implementations to provide static methods. For example, for simple text-serialization/deserialization I'd like to be able to define an interface that looked something like this: public interface TextTransformable<T>{ public static T fromText(String text); public String toText(); Since interfaces in Java can't contain static methods though (as noted in a number of other posts/threads: here, here, and here this code doesn't work. What I'm looking for however is some reasonable paradigm to express the same intent, namely symmetric methods, one of which is static, and enforced by the compiler. Right now the best we can come up with is some kind of static factory object or generic factory, neither of which is really satisfactory. Note: in our case our primary use-case is we have many, many "value-object" types - enums, or other objects that have a limited number of values, typically carry no state beyond their value, and which we parse/de-parse thousands of time a second, so actually do care about reusing instances (like Float, Integer, etc.) and its impact on memory consumption/g.c. Any thoughts?

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  • java: retrieving the "canonical value" from a Set<T> where T has a custom equals()

    - by Jason S
    I have a class Foo which overrides equals() and hashCode() properly. I would like to also would like to use a HashSet<Foo> to keep track of "canonical values" e.g. I have a class that I would like to write like this, so that if I have two separate objects that are equivalent I can coalesce them into references to the same object: class Canonicalizer<T> { final private Set<T> values = new HashSet<T>(); public T findCanonicalValue(T value) { T canonical = this.values.get(value); if (canonical == null) { // not in the set, so put it there for the future this.values.add(value); return value; } else { return canonical; } } } except that Set doesn't have a "get" method that would return the actual value stored in the set, just the "contains" method that returns true or false. (I guess that it assumes that if you have an object that is equal to a separate object in the set, you don't need to retrieve the one in the set) Is there a convenient way to do this? The only other thing I can think of is to use a map and a list: class Canonicalizer<T> { // warning: neglects concurrency issues final private Map<T, Integer> valueIndex = new HashMap<T, Integer>(); final private List<T> values = new ArrayList<T>(); public T findCanonicalValue(T value) { Integer i = this.valueIndex.get(value); if (i == null) { // not in the set, so put it there for the future i = this.values.size(); this.values.add(value); this.valueIndex.put(value, i); return value; } else { // in the set return this.values.get(i); } } }

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  • Google local search API - callback never called

    - by Laurent Luce
    Hello, I am trying to retrieve some local restaurants using the LocalSearch Google API. I am initializing the search objects in the OnLoad function and I am calling the searchControl execute function when the user clicks on a search button. The problem is that my function attached to setSearchCompleteCallback never get called. Please let me know what I am doing wrong here. <script src="http://www.google.com/jsapi"></script> <script type="text/javascript"> google.load('maps' , '2'); google.load('search' , '1'); var searcher, searchControl; function OnLoad() { searchControl = new google.search.SearchControl(); searcher = new google.search.LocalSearch(); // create the object // Add the searcher to the SearchControl searchControl.addSearcher(searcher); searchControl.setSearchCompleteCallback(searcher , function() { var results = searcher.results; // Grab the results array // We loop through to get the points for (var i = 0; i < results.length; i++) { var result = results[i]; } }); $('#user_search_address').live('click', function() { g_searchControl.execute('pizza san francisco'); }); } google.setOnLoadCallback(OnLoad); </script>

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  • OpenCV. cvFnName() works, but cv::FunName() doesn't work

    - by Innuendo
    I'm using OpenCV to write a plugin for a simulator. I've made an OpenCV project (single - not a plugin) and it works fine. When I added OpenCV libs to the plugin project, I added all libs required. Visual Studio 2010 doesn't highlight any code line with red. All looks fine and compiles fine. But in execution, the program halts with a Runtime Error on any cv::function. For example: cv::imread, or cv::imwrite. But if I replace them with cvLoadImage() and cvSaveImage(), it works fine. Why does this happen? I don't want to rewrite the whole script in old-api-style (cvFnName). It means I should change all Mat objects to IplImages, and so on. UPDATE: // preparing template ifstream ifile(tmplfilename); if ( !FILE_LOADED && ifile ) { // loading template file Mat tmpl = cv::imread(tmplfilename, 1); // << here occurs error FILE_LOADED = true; } Mat src; Bmp2Mat(hDC, hBitmap, src); TargetDetector detector(src, tmpl); detector.detectTarget(); If I change to: if ( !FILE_LOADED && ifile ) { IplImage* tmpl = 0; tmpl = cvLoadImage(tmplfilename, 1); // no error occurs } And then no error occurs. Early it displayed some Runtime Error. Now, I wanted to copy exact message and it just crashes the application (simulator, what I am pluginning). It displays window error - to kill process or no. (I can't show exact message, because I'm using russian windows now)

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  • rails xml to active record object

    - by Brian D.
    I've been googling for a while to try and convert and incoming XML request into an active record object. I've tried using the ActiveRecordObject.new.from_xml method but it doesn't seem to handle relationships. For example, say I have the following xml: <blog> <title></title> <blog-pages> <blog-page> <page-number></page-number> <content></content> </blog-page> </blog-pages> </blog> And I have the following model objects: class Blog < ActiveRecord::Base has_many :blog_pages end class BlogPage < ActiveRecord::Base belongs_to :blog end Is there a way to convert the xml into a blog object WITH relationships? Or do I need to manually parse the XML? Thanks in advance.

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  • LINQ .Cast() extension method fails but (type)object works.

    - by Ben Robinson
    To convert between some LINQ to SQL objects and DTOs we have created explicit cast operators on the DTOs. That way we can do the following: DTOType MyDTO = (LinqToSQLType)MyLinq2SQLObj; This works well. However when you try to cast using the LINQ .Cast() extension method it trows an invalid cast exception saying cannot cast type Linq2SQLType to type DTOType. i.e. the below does not work List<DTO.Name> Names = dbContact.tNames.Cast<DTO.Name>() .ToList(); But the below works fine: DAL.tName MyDalName = new DAL.tName(); DTO.Name MyDTOName = (DTO.Name)MyDalName; and the below also works fine List<DTO.Name> Names = dbContact.tNames.Select(name => (DTO.Name)name) .ToList(); Why does the .Cast() extension method throw an invalid cast exception? I have used the .Cast() extension method in this way many times in the past and when you are casting something like a base type to a derived type it works fine, but falls over when the object has an explicit cast operator.

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  • WPF - Extend ListView with checkable AND selectable ListViewItems

    - by Marks
    Hi there. I already read many examples on extending ListViews with checkboxes bound with IsSelected. But I want something more. I want a seperation between the checked and selected state, so i get a ListBox that has a single selected item, but can have multiple checked items. Unfortunately ListViewItem does not have a property for checked and I dont see a possibility to get the ListView to work with a custom CheckableListViewItem. Of course i could use a List of objects with a checked property as ItemSource, but I dont think thats a good way to go. Checked or not is a matter of the list or item-container, not of the object listed in it. Beside that I dont want all my classes like user, role, group to have counterparts like checkableUser, checkableRole and checkableGroup. The behaviour i want can be easyly accomblished for the UI with a <DataTemplate x:Key="CheckBoxCell"> <StackPanel Orientation="Horizontal"> <CheckBox /> </StackPanel> </DataTemplate> and a <GridViewColumn CellTemplate="{StaticResource CheckBoxCell}" Width="30"/> But without a binding on the checkbox i cant check if it is checked or not. Is there any way to accomplish something like that? The perfect solution for me would be to have listView1.SelectedItem, listView1.CheckedItems and maybe a listView1.UncheckedItems and of course listView1.CheckItem and listView1.UncheckItem. Thanks for any help.

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  • How does one force construction of a global object in a statically linked library? [MSVC9]

    - by Peter C O Johansson
    I have a global list of function pointers. This list should be populated at startup. Order is not important and there are no dependencies that would complicate static initialization. To facilitate this, I've written a class that adds a single entry to this list in its constructor, and scatter global instances of this class via a macro where necessary. One of the primary goals of this approach is to remove the need for explicitly referencing every instance of this class externally, instead allowing each file that needs to register something in the list to do it independently. Nice and clean. However, when placing these objects in a static library, the linker discards (or rather never links in) these units because no code in them is explicitly referenced. Explicitly referencing symbols in the compilation units would be counterproductive, directly contradicting one of the main goals of the approach. For the same reason, /INCLUDE is not an acceptable option, and /OPT:NOREF is not actually related to this problem. Metrowerks has a __declspec directive for it, GCC has -force_load, but I cannot find any equivalent for MSVC.

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  • Trying to make a plugin system in C++

    - by Pirate for Profit
    I'm making a task-based program that needs to have plugins. Tasks need to have properties which can be easily edited, I think this can be done with Qt's Meta-Object Compiler reflection capabilities (I could be wrong, but I should be able to stick this in a QtPropertyBrowser?) So here's the base: class Task : public QObject { Q_OBJECT public: explicit Task(QObject *parent = 0) : QObject(parent){} virtual void run() = 0; signals: void taskFinished(bool success = true); } Then a plugin might have this task: class PrinterTask : public Task { Q_OBJECT public: explicit PrinterTask(QObject *parent = 0) : Task(parent) {} void run() { Printer::getInstance()->Print(this->getData()); // fictional emit taskFinished(true); } inline const QString &getData() const; inline void setData(QString data); Q_PROPERTY(QString data READ getData WRITE setData) // for reflection } In a nutshell, here's what I want to do: // load plugin // find all the Tasks interface implementations in it // have user able to choose a Task and edit its specific Q_PROPERTY's // run the TASK It's important that one .dll has multiple tasks, because I want them to be associated by their module. For instance, "FileTasks.dll" could have tasks for deleting files, making files, etc. The only problem with Qt's plugin setup is I want to store X amount of Tasks in one .dll module. As far as I can tell, you can only load one interface per plugin (I could be wrong?). If so, the only possible way to do accomplish what I want is to create a FactoryInterface with string based keys which return the objects (as in Qt's Plug-And-Paint example), which is a terrible boilerplate that I would like to avoid. Anyone know a cleaner C++ plugin architecture than Qt's to do what I want? Also, am I safely assuming Qt's reflection capabilities will do what I want (i.e. able to edit an unknown dynamically loaded tasks' properties with the QtPropertyBrowser before dispatching)?

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  • Object Design catalog and resources

    - by Tauren
    I'm looking for web sites, books, or other resources that provide a catalog of object designs used in common scenarios. I'm not looking for generic design patterns, but for samples of actual object designs that were used to solve real problems. For instance, I'm about to build an internal messaging system for a web application, similar to Facebook's messaging system. This system will allow administrators to send messages to all members, to selected groups of members, or to individuals. Members can send messages to other members or groups of members. Fairly common stuff and a feature that I'm sure thousands of web applications require. I know each situation is different and there are a million ways to design this solution. Although this scenario isn't really all that complex, I'm sure the basic design of the necessary objects and relationships for a system like this has already been done many times. It would be nice to review other similar designs before building my own. Is there a place where people can share their designs and others can browse/search through the catalog to review and provide feedback on them? StackOverflow could be used to a degree for this, but doesn't really provide a catalog of designs. Any other resources that would relate?

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