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• How much is too much memory allocation in NDK?

  - by Maximus

  The NDK download page notes that, "Typical good candidates for the NDK are self-contained, CPU-intensive operations that don't allocate much memory, such as signal processing, physics simulation, and so on." I came from a C background and was excited to try to use the NDK to operate most of my OpenGL ES functions and any native functions related to physics, animation of vertices, etc... I'm finding that I'm relying quite a bit on Native code and wondering if I may be making some mistakes. I've had no trouble with testing at this point, but I'm curious if I may run into problems in the future. For example, I have game struct defined (somewhat like is seen in the San-Angeles example). I'm loading vertex information for objects dynamically (just what is needed for an active game area) so there's quite a bit of memory allocation happening for vertices, normals, texture coordinates, indices and texture graphic data... just to name the essentials. I'm quite careful about freeing what is allocated between game areas. Would I be safer setting some caps on array sizes or should I charge bravely forward as I'm going now?

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• Django throws 404 at generic views

  - by x0rg

  I'm trying to get the generic views for a date-based archive working in django. I defined the urls as described in a tutorial, but django returns a 404 error whenever I want to access an url with a variable (such as month or year) in it. It don't even produces a TemplateDoesNotExist-execption. Normal urls without variables work fine. Here's my urlconf: from django.conf.urls.defaults import * from zurichlive.zhl.models import Event info_dict = { 'queryset': Event.objects.all(), 'date_field': 'date', 'allow_future': 'True', } urlpatterns += patterns('django.views.generic.date_based', (r'events/(?P<year>d{4})/(?P<month>[a-z]{3})/(?P<day>w{1,2})/(?P<slug>[-w]+)/$', 'object_detail', dict(info_dict, slug_field='slug',template_name='archive/detail.html')), (r'^events/(?P<year>d{4})/(?P<month>[a-z]{3})/(?P<day>w{1,2})/(?P<slug>[-w]+)/$', 'object_detail', dict(info_dict, template_name='archive/list.html')), (r'^events/(?P<year>d{4})/(?P<month>[a-z]{3})/(?P<day>w{1,2})/$','archive_day',dict(info_dict,template_name='archive/list.html')), (r'^events/(?P<year>d{4})/(?P<month>[a-z]{3})/$','archive_month', dict(info_dict, template_name='archive/list.html')), (r'^events/(?P<year>)/$','archive_year', dict(info_dict, template_name='archive/list.html')), (r'^events/$','archive_index', dict(info_dict, template_name='archive/list.html')), ) When I access /events/2010/may/12/this-is-a-slug I should get to the detail.html template, but instead I get a 404. What am I doing wrong?

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• Elegant Disjunctive Normal Form in Django

  - by Mike

  Let's say I've defined this model: class Identifier(models.Model): user = models.ForeignKey(User) key = models.CharField(max_length=64) value = models.CharField(max_length=255) Each user will have multiple identifiers, each with a key and a value. I am 100% sure I want to keep the design like this, there are external reasons why I'm doing it that I won't go through here, so I'm not interested in changing this. I'd like to develop a function of this sort: def get_users_by_identifiers(**kwargs): # something goes here return users The function will return all users that have one of the key=value pairs specified in **kwargs. Here's an example usage: get_users_by_identifiers(a=1, b=2) This should return all users for whom a=1 or b=2. I've noticed that the way I've set this up, this amounts to a disjunctive normal form...the SQL query would be something like: SELECT DISTINCT(user_id) FROM app_identifier WHERE (key = "a" AND value = "1") OR (key = "b" AND value = "2") ... I feel like there's got to be some elegant way to take the **kwargs input and do a Django filter on it, in just 1-2 lines, to produce this result. I'm new to Django though, so I'm just not sure how to do it. Here's my function now, and I'm completely sure it's not the best way to do it :) def get_users_by_identifiers(**identifiers): users = [] for key, value in identifiers.items(): for identifier in Identifier.objects.filter(key=key, value=value): if not identifier.user in users: users.append(identifier.user) return users Any ideas? :) Thanks!

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• Invoking a method overloaded where all arguments implement the same interface

  - by double07

  Hello, My starting point is the following: - I have a method, transform, which I overloaded to behave differently depending on the type of arguments that are passed in (see transform(A a1, A a2) and transform(A a1, B b) in my example below) - All these arguments implement the same interface, X I would like to apply that transform method on various objects all implementing the X interface. What I came up with was to implement transform(X x1, X x2), which checks for the instance of each object before applying the relevant variant of my transform. Though it works, the code seems ugly and I am also concerned of the performance overhead for evaluating these various instanceof and casting. Is that transform the best I can do in Java or is there a more elegant and/or efficient way of achieving the same behavior? Below is a trivial, working example printing out BA. I am looking for examples on how to improve that code. In my real code, I have naturally more implementations of 'transform' and none are trivial like below. public class A implements X { } public class B implements X { } interface X { } public A transform(A a1, A a2) { System.out.print("A"); return a2; } public A transform(A a1, B b) { System.out.print("B"); return a1; } // Isn't there something better than the code below??? public X transform(X x1, X x2) { if ((x1 instanceof A) && (x2 instanceof A)) { return transform((A) x1, (A) x2); } else if ((x1 instanceof A) && (x2 instanceof B)) { return transform((A) x1, (B) x2); } else { throw new RuntimeException("Transform not implemented for " + x1.getClass() + "," + x2.getClass()); } } @Test public void trivial() { X x1 = new A(); X x2 = new B(); X result = transform(x1, x2); transform(x1, result); }

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• Flex vs GWT again

  - by CK Lee

  Hi all, I am working on a customized web ontology editor (something like http://webprotege.stanford.edu/ which is built by GWT). My backend will be Java+Spring+Hibernate and domain models are in Java. My frontend will be something like WebProtege which requires extensive RPC call. It is quite clear that I should use GWT as I can refer to the open source code. However, due to company policy, I shall consider Flex as well. I understand Flex can remotely invoke Java backend methods via BlazeDS using AMF (Is there a Flex equivalent of GWT-RPC?). I have read discussion on GWT vs Flex vs ?. If I can make full decision sure I will go with GWT. GWT strengths like support right to left characters, support iPhone/iPad, smaller size, support JSON out of the box, support printing are not important considerations for my project. Besides GWT supports Java generic, enum; domain objects can be shared with both GWT client and server; coding are more seamlessly... anyone can suggest other strong reasons that I should only go with GWT? FYI, I have plenty of Java experience but both GWT and Flex are new to me. Thanks.

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• Importing data from third party datasource (open architecture design )

  - by mare

  How would you design an application (classes, interfaces in class library) in .NET when we have a fixed database design on our side and we need to support imports of data from third party data sources, which will most likely be in XML? For instance, let us say we have a Products table in our DB which has columns Id Title Description TaxLevel Price and on the other side we have for instance Products: ProductId ProdTitle Text BasicPrice Quantity. Currently I do it like this: Have the third party XML convert to classes and XSD's and then deserialize its contents into strong typed objects (what we get as a result of this process is classes like ThirdPartyProduct, ThirdPartyClassification, etc.). Then I have methods like this: InsertProduct(ThirdPartyProduct newproduct) I do not use interfaces at the moment but I would like them to. What I would like is implement something like public class Contoso_ProductSynchronization : ProductSynchronization InsertProduct(ContosoProduct p) where ProductSynchronization will be an interface or abstract class. There will most likely be many implementations of ProductSynchronization. I cannot hardcode the types - classes like ContosoProduct, NorthwindProduct might be created from the third party XML's (so preferably I would continue to use deserialization). Hopefully someone will understand what I'm trying to explain here. Just imagine you are the seller and you have numerous providers and each one uses their own proprietary XML format. I don't mind the development, which will of course be needed everytime new format appears, because it will only require 10-20 methods to be implemented, I just want the architecture to be open and support that.

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• Django ManyToMany Membership errors making associations

  - by jmitchel3

  I'm trying to have a "member admin" in which they have hundreds of members in the group. These members can be in several groups. Admins can remove access for the member ideally in the view. I'm having trouble just creating the group. I used a ManytoManyField to get started. Ideally, the "member admin" would be able to either select existing Users OR it would be able to Add/Invite new ones via email address. Here's what I have: #views.py def membership(request): group = Group.objects.all().filter(user=request.user) GroupFormSet = modelformset_factory(Group, form=MembershipForm) if request.method == 'POST': formset = GroupFormSet(request.POST, request.FILES, queryset=group) if formset.is_valid(): formset.save(commit=False) for form in formset: form.instance.user = request.user formset.save() return render_to_response('formset.html', locals(), context_instance=RequestContext(request)) else: formset= GroupFormSet(queryset=group) return render_to_response('formset.html', locals(), context_instance=RequestContext(request)) #models.py class Group(models.Model): name = models.CharField(max_length=128) members = models.ManyToManyField(User, related_name='community_members', through='Membership') user = models.ForeignKey(User, related_name='community_creator', null=True) def __unicode__(self): return self.name class Membership(models.Model): member = models.ForeignKey(User, related_name='user_membership', blank=True, null=True) group = models.ForeignKey(Group, related_name='community_membership', blank=True, null=True) date_joined = models.DateField(auto_now=True, blank=True, null=True) class Meta: unique_together = ('member', 'group') Any ideas? Thank you for your help.

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• NHibernate will not insert a record

  - by Brian Beckham

  I have an application that is now 4+ years old that is exhibiting some odd behavior on our latest deployment. The application uses nHibernate for all inserts / updates / selects, etc. We are currently using .NET 2.0, and nHibernate 1.2 (I know, we need to upgrade) This deployment is on Windows 2008 Server x64, IIS 7.5 - what I have seen so far is that the application runs, but is unable to insert or update records in the DB - reads seem fine so far, but writes are a problem. SOME writes actually work, inserts into some small tables, but most never even make it to the DB. Using SQL Profiler, the insert / updates never make it to the server, and turning log4net up to DEBUG, and show_sql true - the select statements appear, but the insert / update statements never make it into the log at all, and never show up at the server. What's even more odd is that the application seems to be oblivious to this - the commandandclose runs without exception (open session in view with an httpmodule), the domain objects come back with uuid's generated, etc. but never get persisted. Certainly an upgrade is due, but I would hate to try it during a deployment, and without time to accurately test the app. Any ideas?

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• In perl, how can I call a method whose name I have in a string?

  - by Ryan Thompson

  I'm trying to write some abstract code for searching through a list of similar objects for the first one whose attributes match specific values. In order to do this, I need to call a bunch of accessor methods and check all their values one by one. I'd like to use an abstraction like this: sub verify_attribute { my ($object, $attribute_method, $wanted_value) = @_; if ( call_method($object, $attribute_method) ~~ $wanted_value ) { return 1; } else { return; } } Then I can loop through a hash whose keys are accessor method names and whose values are the values I'm looking for for those attributes. For example, if that hash is called %wanted, I might use code like this to find the object I want: my $found_object; FINDOBJ: foreach my $obj (@list_of_objects) { foreach my $accessor (keys %wanted) { next FINDOBJ unless verify_attribute($obj, $accessor, $wanted{$accessor}); } # All attrs verified $found_object = $obj; last FINDOBJ; } Of course, the only problem is that call_method does not exsit. Or does it? How can I call a method if I have a string containing its name? Or is there a better solution to this whole problem?

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• How Best to Replace PL/SQL with C#?

  - by Mike

  Hi, I write a lot of one-off Oracle SQL queries/reports (in Toad), and sometimes they can get complex, involving lots of unions, joins, and subqueries, and/or requiring dynamic SQL, and/or procedural logic. PL/SQL is custom made for handling these situations, but as a language it does not compare to C#, and even if it did, it's tooling does not, and if even that did, forcing yet another language on the team is something to be avoided whenever possible. Experience has shown me that using SQL for the set based processing, coupled with C# for the procedural processing, is a powerful combination indeed, and far more readable, maintainable and enhanceable than PL/SQL. So, we end up with a number of small C# programs which typically would construct a SQL query string piece by piece and/or run several queries and process them as needed. This kind of code could easily be a disaster, but a good developer can make this work out quite well, and end up with very readable code. So, I don't think it's a bad way to code for smaller DB focused projects. My main question is, how best to create and package all these little C# programs that run ad hoc queries and reports against the database? Right now I create little report objects in a DLL, developed and tested with NUnit, but then I continue to use NUnit as the GUI to select and run them. NUnit just happens to provide a nice GUI for this kind of thing, even after testing has been completed. I'm also interested in suggestions for reporting apps generally. I feel like there is a missing piece or product. The perfect tool would allow writing and running C# inside of Toad, or SQL inside of Visual Studio, along with simple reporting facilities. All ideas will be appreciated, but let's make the assumption that PL/SQL is not the solution.

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• EFv1 mapping 1 to many Relationship to POCOs

  - by Scott

  I'm trying to work through a problem where I'm mapping EF Entities to POCO which serve as DTO. I have two tables within my database, say Products and Categories. A Product belongs to one category and one category may contain many Products. My EF entities are named efProduct and efCategory. Within each entity there is the proper Navigation Property between efProduct and efCategory. My Poco objects are simple public class Product { public string Name { get; set; } public int ID { get; set; } public double Price { get; set; } public Category ProductType { get; set; } } public class Category { public int ID { get; set; } public string Name { get; set; } public List<Product> products { get; set; } } To get a list of products I am able to do something like public IQueryable<Product> GetProducts() { return from p in ctx.Products select new Product { ID = p.ID, Name = p.Name, Price = p.Price ProductType = p.Category }; } However there is a type mismatch error because p.Category is of type efCategory. How can I resolve this? That is, how can I convert p.Category to type Category? I know in .NET EF has added support for POCO, but I'm forced to use .NET 3.5 SP1.

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• Automatically creating DynaActionForms in Mockrunner via struts-config.xml

  - by T Reddy

  I'm switching from MockStrutsTestCase to Mockrunner and I'm finding that having to manually re-create all of my DynaActionForms in Mockrunner is a pain...there has to be an easier way?! Can somebody offer a tip to simplify this process? For instance, this form bean definition in struts-config.xml: <form-bean name="myForm" type="org.apache.struts.action.DynaActionForm"> <form-property name="property" type="java.lang.String"/> </form-bean> results in this code in Mockrunner: //define form config FormBeanConfig config = new FormBeanConfig(); config.setName("myForm"); config.setType(DynaActionForm.class.getName()); FormPropertyConfig property = new FormPropertyConfig(); property.setName("property"); property.setType("java.lang.String"); config.addFormPropertyConfig(property); //create mockrunner objects ActionMockObjectFactory factory = new ActionMockObjectFactory(); ActionTestModule module = new ActionTestModule(factory); DynaActionForm form = module.createDynaActionForm(config); Now imagine that I have dozens of DynaActionForms with dozens of attributes...that stinks!

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• Why is my element variable always null in this foreach loop?

  - by ZeroDivide

  Here is the code: public IEnumerable<UserSummary> getUserSummaryList() { var db = new entityContext(); List<UserSummary> model = new List<UserSummary>(); List<aspnet_Users> users = (from user in db.aspnet_Users select user).ToList<aspnet_Users>(); foreach (aspnet_Users u in users) //u is always null while users is a list that contains 4 objects { model.Add(new UserSummary() { UserName = u.UserName, Email = u.aspnet_Membership.Email, Role = Roles.GetRolesForUser(u.UserName).First(), AdCompany = u.AD_COMPANIES.ad_company_name != null ? u.AD_COMPANIES.ad_company_name : "Not an Advertiser", EmployeeName = u.EMPLOYEE.emp_name != null ? u.EMPLOYEE.emp_name : "Not an Employee" }); } return model; } For some reason the u variable in the foreach loop is always null. I've stepped through the code and the users collection is always populated. The table entity for db.aspnet_Users is the users table that comes with asp.net membership services. I've only added a couple associations to it. edit : image of debugger

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• What problem did MS solve by creating PowerShell? [closed]

  - by Fred

  I'm asking because PowerShell confuses me. I've been trying to write some deployment scripts using PowerShell and I've been less than enthused by the result. I have a co-worker who loves PowerShell and defends it at every turn. Said co-worker claims PowerShell was never written to be a strong shell, but instead was written to: a) Allow you to peek and poke at .NET assemblies on the command-line (why is this a reason for PowerShell to exist?) b) To be hosted in .NET applications for automation, similar to DCOP in KDE and how Gnome is using CORBA. c) to be treated as ".NET script" rather than as an actual shell (related to b). I've always felt like Windows was missing a decent way to bang out automation scripts. cmd is too simplistic in many cases, and WSH is too obtuse (although the combination can be used successfully, I'm not a fan). When I first heard about PowerShell I felt like Windows was finally getting a decent shell that would be able to help with automation of many tasks, but recent experiences, and my co-worker, tell me otherwise. To be clear, I don't take issue with the fact that it's built on .NET, or that it passes objects around rather than text (despite my Unix background :]), and I'm not arguing that PowerShell is useless, but from what I can see, it doesn't solve the problem I was hoping it would solve very well. As soon as you step outside of the .NET/Powershell world, things quit being nice and cozy for you. So with all that out of the way, what problem did MS solve by creating PowerShell, or is it some political bastard child as I suspect? I've googled and haven't hit upon anything that sufficiently answered that for me, but the more citations the better.

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• Python list should be empty on class instance initialisation, but it's not. Why?

  - by canavanin

  Hi everyone! I would like to create instances of a class containing a list that's empty by default; instead of later setting this list to the final full list I would like to successively add items to it. Here's a piece of sample code illustrating this: #!/usr/bin/python class test: def __init__(self, lst=[], intg=0): self.lista = lst self.integer = intg name_dict = {} counter = 0 for name in ('Anne', 'Leo', 'Suzy'): counter += 1 name_dict[name] = test() name_dict[name].integer += 1 name_dict[name].lista.append(counter) print name, name_dict[name].integer, name_dict[name].lista When I ran the above program I expected to get Anne 1 [1] Leo 1 [2] Suzy 1 [3] as I assumed lista to always be initialised to an empty list. What I got instead was this: Anne 1 [1] Leo 1 [1, 2] Suzy 1 [1, 2, 3] If I replace self.lista = lst by self.lista = [] it works fine, just like when I add the line name_dict[name].lista = [] to the for loop. Why is it that the contents of the previous objects' lists are retained, yet their values of integer aren't? I am rather new to Python, so it would be great if someone could point out to me where my thoughts/assumptions have gone astray. Thanks a lot in advance for your replies.

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• python list/dict property best practice

  - by jterrace

  I have a class object that stores some properties that are lists of other objects. Each of the items in the list has an identifier that can be accessed with the id property. I'd like to be able to read and write from these lists but also be able to access a dictionary keyed by their identifier. Let me illustrate with an example: class Child(object): def __init__(self, id, name): self.id = id self.name = name class Teacher(object): def __init__(self, id, name): self.id = id self.name = name class Classroom(object): def __init__(self, children, teachers): self.children = children self.teachers = teachers classroom = Classroom([Child('389','pete')], [Teacher('829','bob')]) This is a silly example, but it illustrates what I'm trying to do. I'd like to be able to interact with the classroom object like this: #access like a list print classroom.children[0] #append like it's a list classroom.children.append(Child('2344','joe')) #delete from like it's a list classroom.children.pop(0) But I'd also like to be able to access it like it's a dictionary, and the dictionary should be automatically updated when I modify the list: #access like a dict print classroom.childrenById['389'] I realize I could just make it a dict, but I want to avoid code like this: classroom.childrendict[child.id] = child I also might have several of these properties, so I don't want to add functions like addChild, which feels very un-pythonic anyway. Is there a way to somehow subclass dict and/or list and provide all of these functions easily with my class's properties? I'd also like to avoid as much code as possible.

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• Why are controls (null) in awakeFromNib?

  - by fuzzygoat

  This is a follow on from another question regarding why I could not set UIControls in awakeFromNib. The answer to that is that as you can see below the controls are nil in the awakeFromNib, although they are initialised to the correct objects by the time we get to viewDidLoad. I setup the view the same as I always do, should I be doing something different to access them here, the xib(nib) was designed and saved with the current version of Image Builder. CODE: @interface iPhone_TEST_AwakeFromNibViewController : UIViewController { UILabel *myLabel; UIImageView *myView; } @property(nonatomic, retain)IBOutlet UILabel *myLabel; @property(nonatomic, retain)IBOutlet UIImageView *myView; @end . @synthesize myLabel; @synthesize myView; -(void)awakeFromNib { NSLog(@"awakeFromNib ..."); NSLog(@"myLabel: %@", [myLabel class]); NSLog(@"myView : %@", [myView class]); //[myLabel setText:@"AWAKE"]; [super awakeFromNib]; } -(void)viewDidLoad { NSLog(@"viewDidLoad ..."); NSLog(@"myLabel: %@", [myLabel class]); NSLog(@"myView : %@", [myView class]); //[myLabel setText:@"VIEW"]; [super viewDidLoad]; } OUTPUT: awakeFromNib ... myLabel: (null) myView : (null) viewDidLoad ... myLabel: UILabel myLabel: UIImageView Much appreciated ... gary

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• Flex Tree with infinite parents and children

  - by Tempname

  I am working on a tree component and I am having a bit of the issue with populating the data-provider for this tree. The data that I get back from my database is a simple array of value objects. Each value object has 2 properties. ObjectID and ParentID. For parents the ParentID is null and for children the ParentID is the ObjectID of the parent. Any help with this is greatly appreciated. Essentially the tree should look something like this: Parent1 Child1 Child1 Child2 Child1 Child2 Parent2 Child1 Child2 Child3 Child1 This is the current code that I am testing with: public function setDataProvider(data:Array):void { var tree:Array = new Array(); for(var i:Number = 0; i < data.length; i++) { // do the top level array if(!data[i].parentID) { tree.push(data[i], getChildren(data[i].objectID, data)); } } function getChildren(objectID:Number, data:Array):Array { var childArr:Array = new Array(); for(var k:Number = 0; k < data.length; k++) { if(data[k].parentID == objectID) { childArr.push(data[k]); //getChildren(data[k].objectID, data); } } return childArr; } trace(ObjectUtil.toString(tree)); } Here is a cross section of my data: ObjectID ParentID 1 NULL 10 NULL 8 NULL 6 NULL 4 6 3 6 9 6 2 6 11 7 7 8 5 8

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• ListView - Index and Position Behavior upon restart()

  - by tunneling

  I am using a ListView with an ArrayAdapter that holds objects. When I select an item, I am capturing the position and index of the selected item. If I scroll down prior to selection, the position and index represent the location of the item in the list. Selecting that items takes me to another activity. When I use the back button to return to the list, it seems that the ListView get's a new position and index for the visible items. As a result, I can't figure out how to reference the selected item during the restart() of the ListView Activity. I have tried to caputure position and index, but as I've said, they change upon returning to the Activity. Is my understanding of the ListView "redraw" correct? Does it renumber my items based on what's visible? -When in the life cycle is getView() called? Is there a way to force an update to the ListView so that my caputured index still points to the same object? Thanks, Jason

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• SWIG_NewPointerObj and values always being nil

  - by Tom J Nowell

  I'm using SWIG to wrap C++ objects for use in lua, and Im trying to pass data to a method in my lua script, but it always comes out as 'nil' void CTestAI::UnitCreated(IUnit* unit){ lua_getglobal(L, "ai"); lua_getfield(L, -1, "UnitCreated"); swig_module_info *module = SWIG_GetModule( L ); swig_type_info *type = SWIG_TypeQueryModule( module, module, "IUnit *" ); SWIG_NewPointerObj(L,unit,type,0); lua_epcall(L, 1, 0); } Here is the lua code: function AI:UnitCreated(unit) if(unit == nil) then game:SendToConsole("I CAN HAS nil ?") else game:SendToConsole("I CAN HAS UNITS!!!?") end end unit is always nil. I have checked and in the C++ code, the unit pointer is never invalid/null I've also tried: void CTestAI::UnitCreated(IUnit* unit){ lua_getglobal(L, "ai"); lua_getfield(L, -1, "UnitCreated"); SWIG_NewPointerObj(L,unit,SWIGTYPE_p_IUnit,0); lua_epcall(L, 1, 0); } with identical results. Why is this failing? How do I fix it?

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• GUID or int entity key with SQL Compact/EF4?

  - by David Veeneman

  This is a follow-up to an earlier question I posted on EF4 entity keys with SQL Compact. SQL Compact doesn't allow server-generated identity keys, so I am left with creating my own keys as objects are added to the ObjectContext. My first choice would be an integer key, and the previous answer linked to a blog post that shows an extension method that uses the Max operator with a selector expression to find the next available key: public static TResult NextId<TSource, TResult>(this ObjectSet<TSource> table, Expression<Func<TSource, TResult>> selector) where TSource : class { TResult lastId = table.Any() ? table.Max(selector) : default(TResult); if (lastId is int) { lastId = (TResult)(object)(((int)(object)lastId) + 1); } return lastId; } Here's my take on the extension method: It will work fine if the ObjectContext that I am working with has an unfiltered entity set. In that case, the ObjectContext will contain all rows from the data table, and I will get an accurate result. But if the entity set is the result of a query filter, the method will return the last entity key in the filtered entity set, which will not necessarily be the last key in the data table. So I think the extension method won't really work. At this point, the obvious solution seems to be to simply use a GUID as the entity key. That way, I only need to call Guid.NewGuid() method to set the ID property before I add a new entity to my ObjectContext. Here is my question: Is there a simple way of getting the last primary key in the data store from EF4 (without having to create a second ObjectContext for that purpose)? Any other reason not to take the easy way out and simply use a GUID? Thanks for your help.

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• JPA returning null for deleted items from a set

  - by Jon

  This may be related to my question from a few days ago, but I'm not even sure how to explain this part. (It's an entirely different parent-child relationship.) In my interface, I have a set of attributes (Attribute) and valid values (ValidValue) for each one in a one-to-many relationship. In the Spring MVC frontend, I have a page for an administrator to edit these values. Once it's submitted, if any of these fields (as <input> tags) are blank, I remove the ValidValue object like so: Set<ValidValue> existingValues = new HashSet<ValidValue>(attribute.getValidValues()); Set<ValidValue> finalValues = new HashSet<ValidValue>(); for(ValidValue validValue : attribute.getValidValues()) { if(!validValue.getValue().isEmpty()) { finalValues.add(validValue); } } existingValues.removeAll(finalValues); for(ValidValue removedValue : existingValues) { getApplicationDataService().removeValidValue(removedValue); } attribute.setValidValues(finalValues); getApplicationDataService().modifyAttribute(attribute); The problem is that while the database is updated appropriately, the next time I query for the Attribute objects, they're returned with an extra entry in their ValidValue set -- a null, and thus, the next time I iterate through the values to display, it shows an extra blank value in the middle. I've confirmed that this happens at the point of a merge or find, at the point of "Execute query ReadObjectQuery(entity.Attribute). Here's the code I'm using to modify the database (in the ApplicationDataService): public void modifyAttribute(Attribute attribute) { getJpaTemplate().merge(attribute); } public void removeValidValue(ValidValue removedValue) { ValidValue merged = getJpaTemplate().merge(removedValue); getJpaTemplate().remove(merged); } Here are the relevant parts of the entity classes: Entity @Table(name = "attribute") public class Attribute { @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "attribute") private Set<ValidValue> validValues = new HashSet<ValidValue>(0); } @Entity @Table(name = "valid_value") public class ValidValue { @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "attr_id", nullable = false) private Attribute attribute; }

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• Cleaning up when exiting an OpenGL app

  - by Daniel

  This might be a dumb question but I've spent some time asking Google and haven't been able to find anything. I have an an OSX OpenGL app I'm trying to modify. When I create the app a whole bunch of initialisation functions are called -- including methods where I can specify my own mouse and keyboard handlers etc. For example: glutInit(&argc, argv); glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA); glutInitWindowPosition(100, 100); glutInitWindowSize(700, 700); glutCreateWindow("Map Abstraction"); glutReshapeFunc(resizeWindow); glutDisplayFunc(renderScene); glutIdleFunc(renderScene); glutMouseFunc(mousePressedButton); glutMotionFunc(mouseMovedButton); glutKeyboardFunc(keyPressed); At some point I pass control to glutMainLoop and my application runs. In the process of running I create a whole bunch of objects. I'd like to clean these up. Is there any way I can tell GLUT to call a cleanup method before it quits?

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• ASP.NET server data persistence

  - by Wayne Werner

  Hi, I'm not really sure exactly how the question should be phrased, so please be patient if I ask the wrong thing. I'm writing an ASP.NET application using VB as the code behind language. I have a data access class that connects to the DB to run the query (parameterized, of course), and another class to perform the validation tasks - I access this class from my aspx page. What I would like is to be able to store the data server side and wait for the user to choose from a few options based on the validity of the data. But unless my understanding is completely off, having persistent data objects on the server will give problems when multiple users connect? My ultimate goal is that once the data has been validated the end user can't modify it. Currently I'm validating the data, but I still have to retrieve it from the web form AFTER the user says OK, which obviously leaves open the possibility of injecting bad data either accidentally (unlikely) or on purpose (also unlikely for the use, but I'd prefer not to take the chance). So am I completely off in my understanding? If so, can someone point me to a resource that provides some instructions on keeping persistent data on the server, or provide instruction? Thanks!

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• Optimize a views drawing code

  - by xon1c

  Hi, in a simple drawing application I have a model which has a NSMutableArray curvedPaths holding all the lines the user has drawn. A line itself is also a NSMutableArray, containing the point objects. As I draw curved NSBezier paths, my point array has the following structure: linePoint, controlPoint, controlPoint, linePoint, controlPoint, controlPoint, etc... I thought having one array holding all the points plus control points would be more efficient than dealing with 2 or 3 different arrays. Obviously my view draws the paths it gets from the model, which leads to the actual question: Is there a way to optimize the following code (inside the view's drawRect method) in terms of speed? int lineCount = [[model curvedPaths] count]; // Go through paths for (int i=0; i < lineCount; i++) { // Get the Color NSColor *theColor = [model getColorOfPath:[[model curvedPaths] objectAtIndex:i]]; // Get the points NSArray *thePoints = [model getPointsOfPath:[[model curvedPaths] objectAtIndex:i]]; // Create a new path for performance reasons NSBezierPath *path = [[NSBezierPath alloc] init]; // Set the color [theColor set]; // Move to first point without drawing [path moveToPoint:[[thePoints objectAtIndex:0] myNSPoint]]; int pointCount = [thePoints count] - 3; // Go through points for (int j=0; j < pointCount; j+=3) { [path curveToPoint:[[thePoints objectAtIndex:j+3] myNSPoint] controlPoint1:[[thePoints objectAtIndex:j+1] myNSPoint] controlPoint2:[[thePoints objectAtIndex:j+2] myNSPoint]]; } // Draw the path [path stroke]; // Bye stuff [path release]; [theColor release]; } Thanks, xonic

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