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  • Memory management in Qt?

    - by Martin
    I'm quite new to Qt and am wondering on some basic stuff with memory management and the life of objects. When do I need to delete / destroy my objects? Is any of this handled automatically? In the example below, which of the objects I create do I need to delete? What happens to the instance variable myOtherClass when myClass is destroyed? What happens if I don't delete / destroy my objects at all, will that be a problem to memory? in MyClass.h: class MyClass { public: MyClass(); ~MyClass(); MyOtherClass *myOtherClass; }; in MyClass.cpp: MyClass::MyClass() { myOtherClass = new MyOtherClass(); MyOtherClass myOtherClass2; QString myString = "Hello"; } As you can see this is quite newbie-easy stuff but where can I learn about this in an easy way? Thanks really much

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  • Validating disconnected POCOs

    - by jonathanconway
    In my ASP.NET application I have separate projects for the Data, Business and UI layers. My business layer is composed of plain objects with declarative validation, using DataAnnotations. Problem is, when it comes to save them, I'm not sure how to process the validation, since they're not bound directly to any data context, but rather, are mapped to separate data-layer objects. Is there a way to trigger validation on these kinds of objects?

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  • Django excluding specific instances from queryset without using field lookup

    - by Agos
    Hi, I sometimes have the need to make sure some instances are excluded from a queryset. This is the way I do it usually: unwanted_instance = Mymodel.objects.get(pk=bad_luck_number) uninteresting_stuff_happens() my_results = MyModel.objects.exclude(id=unwanted_instance.id) or, if I have more of them: my_results = MyModel.objects.exclude(id_in=[uw_in1.id, uw_in2.id, uw_in3.id]) This 'feels' a bit clunky, so I tried if I was lucky: my_ideally_obtained_results = MyModel.objects.exclude(unwanted_instance) Which doesn't work. But I read here on SO that a subquery can be used as parameter for exclude. Am I out of luck? Am I missing some functionality (checked the docs, but didn't find any useful pointer)

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  • Project change makes qtp to fail

    - by Onnesh
    We are using 2 or more projects in an application to be opened. For e.g. HT1000 & HT1200 will be opened by the application, objects are the same(or common) for both the projects. Code uses the values in excel framework for running the test cases as parent to identify the child objects for e.g. Window("HT1000").Dialog("parts").Click("OK") but when we just change the parent name in excel framework as "HT1200" the objects for HT1200 are not getting accessed. How to resolve this? Is it needed to again add the HT1200 project & objects in the object repo of qtp?

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  • WPF Listview- What would be the best way to display data from different ObservableCollections based

    - by highone
    I have three ObservableCollections: CharacterCollection, LocationCollection, and ItemCollection. They are all collections of objects; CharacterCollection is a collection of Character Objects. I need to display, in the listview, information from the collection determined by the user clicking on a button. I would prefer to use databinding, but I don't see a clear cut way to do that with multiple collections containing different types of objects. What would be the best way to easily switch between collections?

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  • C#: Put member variables into a list.

    - by David
    Hi all Assuming I have a method which accepts an IList or similar thing as a parameter: public void JiggleMyList(IList<string> list)... Is there an easy way that I can pass in string members of a list of objects? I mean, if for example, I have a list of Person objects which expose a string property called FullName, is there a quick way to stuff the FullNames of all the Person objects into the method parameter, or do I have to create a new List and iterate through the Person objects: List<string> fullNames = new List<string>; foreach (Person person in people) { fullNames.Add(person.FullName); } JiggleMyList(fullNames); I come across this all the time, and it would be nice if there was a shortcut. Many thanks David

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  • Using ret with FASM on Win32

    - by Jon Purdy
    I'm using SDL with FASM, and have code that's minimally like the following: format ELF extrn _SDL_Init extrn _SDL_SetVideoMode extrn _SDL_Quit extrn _exit SDL_INIT_VIDEO equ 0x00000020 section '.text' public _SDL_main _SDL_main: ccall _SDL_Init, SDL_INIT_VIDEO ccall _SDL_SetVideoMode, 640, 480, 32, 0 ccall _SDL_Quit ccall _exit, 0 ; Success, or ret ; failure. With the following quick-and-dirty makefile: SOURCES = main.asm OBJECTS = main.o TARGET = SDLASM.exe FASM = C:\fasm\fasm.exe release : $(OBJECTS) ld $(OBJECTS) -LC:/SDL/lib/ -lSDLmain -lSDL -LC:/MinGW/lib/ -lmingw32 -lcrtdll -o $(TARGET) --subsystem windows cleanrelease : del $(OBJECTS) %.o : %.asm $(FASM) $< $@ Using exit() (or Windows' ExitProcess()) seems to be the only way to get this program to exit cleanly, even though I feel like I should be able to use retn/retf. When I just ret without calling exit(), the application does not terminate and needs to be killed. Could anyone shed some light on this? It only happens when I make the call to SDL_SetVideoMode().

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  • PHP anonymous functions scope question

    - by Dan
    Hi, I'm trying to sort an array of objects by a common property, however I cannot get my $property parameter to register in the inner function (I can use it in the outer one OK). The way I read the documentation, it sounded like the parameter would be available, have I misunderstood something? Here is what I have: public static function sortObjectsByProperty($objects, $property) { function compare_object($a, $b) { $a = $a->$property; $b = $b->$property; if ($a->$property == $b->$property) { return 0; } return ($a->$property > $b->$property) ? +1 : -1; } usort($objects, 'compare_object'); return $objects; } Any advice appreciated. Thanks.

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  • SQL Alchemy MVC and cross controller joins

    - by Khorkrak
    When using SQL Alchemy for abstracting your data access layer and using controllers as the way to access objects from that abstraction layer, how should joins be handled? So for example, say you have an Orders controller class that manages Order objects such that it provides getOrder, saveOrder, etc methods and likewise a similar controller for User objects. First of all do you even need these controllers? Should you instead just treat SQL Alchemy as "the" thing for handling data access. Why bother with object oriented controller stuff there when you instead have a clean declarative way to obtain and persist objects without having to write SQL directly either. Well one reason could be that perhaps you may want to replace SQL Alchemy with direct SQL or Storm or whatever else. So having controller classes there to act as an intermediate layer helps limit what would need to change then. Anyway - back to the main question - so assuming you have these two controllers, now lets say you want the list of orders for a certain set of users meeting some criteria. How do you go about doing this? Generally you don't want the controllers crossing domains - the Orders controllers knows only about Orders and the User controller just about Users - they don't mess with each other. You also don't want to go fetch all the Users that match and then feed a big list of user ids to the Orders controller to go find the matching Orders. What's needed is a join. Here's where I'm stuck - that seems to mean either the controllers must cross domains or perhaps they should be done away with altogether and you simply do the join via SQL Alchemy directly and get the resulting User and / or Order objects as needed. Thoughts?

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  • Avoiding null point exception in el in JSF

    - by Buddhika Ariyaratne
    I am developing a JSF application with JPA(EclipseLink 2.0) and Primefaces. I want to know is there any way to avoid null point exception when el calls a property of a null object. I have described the situation. I have Bill class. There may be no or more BillItem objects with a Bill objects. Each BillItem object have Objects like Make, Country, Manufacturer, etc objects. I am displaying several properties of a bill within a single JSF file like this. "#{billControlled.bill.billItem.modal.name}" But if a bill is not selected, or when there are no bill items for a selected bill, the properties accessing in the el are null. I can avoid this by creating new objects for every bill, for example, new make for a new bill item, etc or by creating new properties in the controller itself for all the properties. But that is a very long way and feel like rudimentory. Is there any good practice to avoid this null point exception in el in JSF?

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  • Do you know of a free .Net component for visual flow model graph design and editing?

    - by Ivan
    An app (C#4, WinForms, Entity Framework, SQL Server 2008) of mine maintains a graph of interconnected objects, each having some simple member fields and a set of many directed (in and out) one-to-one links to other objects. I'd like to offer a user an ability to view and edit this graph visually some way, creating and removing connections, modifying objects attributes values and introducing/dropping objects. I suppose there has to be a framework (at list a primitive kind of) for this as visual model design tools are pretty common to meet. Do you know one?

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  • Ajax data two-way data binding strategies?

    - by morgancodes
    I'd like to 1) Draw create form fields and populate them with data from javascript objects 2) Update those backing objects whenever the value of the form field changes Number 1 is easy. I have a few js template systems I've been using that work quite nicely. Number 2 may require a bit of thought. A quick google search on "ajax data binding" turned up a few systems which seem basically one-way. They're designed to update a UI based on backing js objects, but don't seem to address the question of how to update those backing objects when changes are made to the UI. Can anyone recommend any libraries which will do this for me? It's something I can write myself without too much trouble, but if this question has already been thought through, I'd rather not duplicate the work.

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  • Hierarchy / Flyweight / Instancing Problem in Python

    - by Dan
    Here is the problem I am trying to solve, (I have simplified the actual problem, but this should give you all the relevant information). I have a hierarchy like so: 1.A 1.B 1.C 2.A 3.D 4.B 5.F (This is hard to illustrate - each number is the parent, each letter is the child). Creating an instance of the 'letter' objects is expensive (IO, database costs, etc), so should only be done once. The hierarchy needs to be easy to navigate. Children in the hierarchy need to have just one parent. Modifying the contents of the letter objects should be possible directly from the objects in the hierarchy. There needs to be a central store containing all of the 'letter' objects (and only those in the hierarchy). 'letter' and 'number' objects need to be possible to create from a constructor (such as Letter(**kwargs) ). It is perfectably acceptable to expect that when a letter changes from the hierarchy, all other letters will respect the same change. Hope this isn't too abstract to illustrate the problem. What would be the best way of solving this? (Then I'll post my solution) Here's an example script: one = Number('one') a = Letter('a') one.addChild(a) two = Number('two') a = Letter('a') two.addChild(a) for child in one: child.method1() for child in two: print '%s' % child.method2()

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  • How to write async background workers that work on WPF flowdocument

    - by iBe
    I'm trying to write a background worker that processes a flowdocument. I can't access the properties of flowdocument objects because of the thread verification. I tried to serialize the document and loaded it on the worker thread which actually solved the thread verfication issue. However, once the processing is complete I also need to use things like TextPointer objects. Those objects now point to a objects in the copy not the original. Can anyone suggest the best way to approach such background processing in WPF?

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  • Deleting entity with child relationships using .Net Entity Framework problem

    - by Am
    My God, EF is so frustrating. I can't seem to be able to get my head around what I need to do so I can delete an object. I seem to be able to remove the object but not the related child objects. Can anyone tell me what is the rule of thumb when you want to delete all related child objects of a given object? I've tried loading all related objects like this: if (!object.childobjects.IsLoaded) object.childobjects.Load(); but once I do the following I get errors related to the relationships: modelcontext.DeleteObject(object); modelcontext.SaveChanges(); Why can't I just load the object using modelcontext.GetObjectByKey and remove it along with its child objects? My other question is can I delete an object using Entity command like so? DELETE e from objectset as e where e.id = 12 I've tried few variations and all of them throw exceptions.

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  • Ret Failure with SDL using FASM on Win32

    - by Jon Purdy
    I'm using SDL with FASM, and have code that's minimally like the following: format ELF extrn _SDL_Init extrn _SDL_SetVideoMode extrn _SDL_Quit extrn _exit SDL_INIT_VIDEO equ 0x00000020 section '.text' public _SDL_main _SDL_main: ccall _SDL_Init, SDL_INIT_VIDEO ccall _SDL_SetVideoMode, 640, 480, 32, 0 ccall _SDL_Quit ccall _exit, 0 ; Success, or ret ; failure. With the following quick-and-dirty makefile: SOURCES = main.asm OBJECTS = main.o TARGET = SDLASM.exe FASM = C:\fasm\fasm.exe release : $(OBJECTS) ld $(OBJECTS) -LC:/SDL/lib/ -lSDLmain -lSDL -LC:/MinGW/lib/ -lmingw32 -lcrtdll -o $(TARGET) --subsystem windows cleanrelease : del $(OBJECTS) %.o : %.asm $(FASM) $< $@ Using exit() (or Windows' ExitProcess()) seems to be the only way to get this program to exit cleanly, even though I feel like I should be able to use retn/retf. When I just ret without calling exit(), the application does not terminate and needs to be killed. Could anyone shed some light on this? It only happens when I make the call to SDL_SetVideoMode().

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  • Inference engine to calculate matching set according to internal rules

    - by Zecrates
    I have a set of objects with attributes and a bunch of rules that, when applied to the set of objects, provides a subset of those objects. To make this easier to understand I'll provide a concrete example. My objects are persons and each has three attributes: country of origin, gender and age group (all attributes are discrete). I have a bunch of rules, like "all males from the US", which correspond with subsets of this larger set of objects. I'm looking for either an existing Java "inference engine" or something similar, which will be able to map from the rules to a subset of persons, or advice on how to go about creating my own. I have read up on rule engines, but that term seems to be exclusively used for expert systems that externalize the business rules, and usually doesn't include any advanced form of inferencing. Here are some examples of the more complex scenarios I have to deal with: I need the conjunction of rules. So when presented with both "include all males" and "exclude all US persons in the 10 - 20 age group," I'm only interested in the males outside of the US, and the males within the US that are outside the 10 - 20 age group. Rules may have different priorities (explicitly defined). So a rule saying "exclude all males" will override a rule saying "include all US males." Rules may be conflicting. So I could have both an "include all males" and an "exclude all males" in which case the priorities will have to settle the issue. Rules are symmetric. So "include all males" is equivalent to "exclude all females." Rules (or rather subsets) may have meta rules (explicitly defined) associated with them. These meta rules will have to be applied in any case that the original rule is applied, or if the subset is reached via inferencing. So if a meta rule of "exclude the US" is attached to the rule "include all males", and I provide the engine with the rule "exclude all females," it should be able to inference that the "exclude all females" subset is equivalent to the "include all males" subset and as such apply the "exclude the US" rule additionally. I can in all likelihood live without item 5, but I do need all the other properties mentioned. Both my rules and objects are stored in a database and may be updated at any stage, so I'd need to instantiate the 'inference engine' when needed and destroy it afterward.

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  • Looking for an elegant way to store one-to-many relationship in coredata when order is important

    - by Eric Schweichler
    I've been trying to come up with a way to solve my problem, but every solution I can think of is messy and makes me want to retch. I have a one-to-many relationship, consisting of a Team object that can have many Member objects. When I built my data model using Xcode, I was given the default NSSet in which to store the member objects, Unfortunately Sets are not ordered and I need to preserve the order of the Member objects and I need to know if there are empty spaces between Members. I thought of Using an NSArray in place of the NSSet and creating a dummy Member object in my data store that I could use to mark vacant a spot between to Member objects, but that solution really feels like too much of a hack to me. Since I'll always have to filter out this dummy Member from any queries. An NSDictionary would be perfect as I could store the Member object references and their positions as Object-Key pairs, (taking care of both order and vacancies) but apparently CoreData does not support NSDictionary. Has anyone had a similar need, and devised a simple solution?

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  • Two different definitions of database schema

    - by AspOnMyNet
    a) I found two definitions of schema: FIRST - A set of information that describes a table is known as a schema, and schemas are used to describe specific tables within a database, as well as entire databases (and the relationship between tables in them, if any). SECOND - A database schema is a way to logically group objects such as tables, views, stored procedures etc. Think of a schema as a container of objects. I assume the two descriptions describe entirely different concepts, which just happen to use the same name? b) A database schema is a way to logically group objects such as tables, views, stored procedures etc. Think of a schema as a container of objects. If I understand the above definition correctly, then database schema is similar to a namespace, only difference being that we can assign access permissions to database schema, while same can’t be done with namespaces? thanx

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  • ORM solutions (JPA; Hibernate) vs. JDBC

    - by Grasper
    I need to be able to insert/update objects at a consistent rate of at least 8000 objects every 5 seconds in an in-memory HSQL database. I have done some comparison performance testing between Spring/Hibernate/JPA and pure JDBC. I have found a significant difference in performance using HSQL.. With Spring/Hib/JPA, I can insert 3000-4000 of my 1.5 KB objects (with a One-Many and a Many-Many relationship) in 5 seconds, while with direct JDBC calls I can insert 10,000-12,000 of those same objects. I cannot figure out why there is such a huge discrepancy. I have tweaked the Spring/Hib/JPA settings a lot trying to get close in performance without luck. I want to use Spring/Hib/JPA for future purposes, expandability, and because the foreign key relationships (one-many and many-many) are difficult to maintain by hand; but the performance requirements seem to point towards using pure JDBC. Any ideas of why there would be such a huge discrepancy?

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  • NSUndoManager, Core Data and selective undo/redo

    - by Combat
    I'm working on a core data application that has a rather large hierarchy of managed objects similar to a tree. When a base object is created, it creates a few child objects which in turn create their own child objects and so on. Each of these child objects may gather information using NSURLConnections. Now, I'd like to support undo/redo with the undoManager in the managedObjectContext. The problem is, if a user creates a base object, then tries to undo that action, the base object is not removed. Instead, one or more of the child objects may be removed. Obviously this type of action is unpredictable and unwanted. So I tried disabling undo registration by default. I did this by calling disableUndoRegistration: before anything is modified in the managedObjectContext. Then, enabling undo registration before base operations such as creating a base object the again re-disabling registrations afterwords. Now when i try to undo, I get this error: undo: NSUndoManager 0x1026428b0 is in invalid state, undo was called with too many nested undo groups Thoughts?

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  • How would the 'Model' in a Rails-type webapp be implemented in a functional programming langauge?

    - by ceptorial
    In MVC web development frameworks such as Ruby on Rails, Django, and CakePHP, HTTP requests are routed to controllers, which fetch objects which are usually persisted to a backend database store. These objects represent things like users, blog posts, etc., and often contain logic within their methods for permissions, fetching and/or mutating other objects, validation, etc. These frameworks are all very much object oriented. I've been reading up recently on functional programming and it seems to tout tremendous benefits such as testability, conciseness, modularity, etc. However most of the examples I've seen for functional programming implement trivial functionality like quicksort or the fibonnacci sequence, not complex webapps. I've looked at a few 'functional' web frameworks, and they all seem to implement the view and controller just fine, but largely skip over the whole 'model' and 'persistence' part. (I'm talking more about frameworks like Compojure which are supposed to be purely functional, versus something Lift which conveniently seems to use the OO part of Scala for the model -- but correct me if I'm wrong here.) I haven't seen a good explanation of how functional programming can be used to provide the metaphor that OO programming provides, i.e. tables map to objects, and objects can have methods which provide powerful, encapsulated logic such as permissioning and validation. Also the whole concept of using SQL queries to persist data seems to violate the whole 'side effects' concept. Could someone provide an explanation of how the 'model' layer would be implemented in a functionally programmed web framework?

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  • How to skip "Loose Object" popup when running 'git gui'

    - by Michael Donohue
    When I run 'git gui' I get a popup that says This repository currently has approximately 1500 loose objects. It then suggests compressing the database. I've done this before, and it reduces the loose objects to about 250, but that doesn't suppress the popup. Compressing again doesn't change the number of loose objects. Our current workflow requires significant use of 'rebase' as we are transitioning from Perforce, and Perforce is still the canonical SCM. Once Git is the canonical SCM, we will do regular merges, and the loose objects problem should be greatly mitigated. In the mean time, I'd really like to make this 'helpful' popup go away.

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