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  • Correct approach to validate attributes of an instance of class

    - by systempuntoout
    Having a simple Python class like this: class Spam(object): __init__(self, description, value): self.description = description self.value = value Which is the correct approach to check these constraints: "description cannot be empty" "value must be greater than zero" Should i: 1.validate data before creating spam object ? 2.check data on __init__ method ? 3.create an is_valid method on Spam class and call it with spam.isValid() ? 4.create an is_valid static method on Spam class and call it with Spam.isValid(description, value) ? 5.check data on setters declaration ? 6.... Could you recommend a well designed\Pythonic\not verbose (on class with many attributes)\elegant approach?

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  • Class properties vs NSArray / NSDictionary

    - by Frank Martin
    I want a custom class object to hold data and have somehow the feeling that creating about 80 properties is not the best way of doing it. Most of the properties would be bool values, so i'm thinking about creating Arrays (keys / values) or (probably better) a NSDictionary attached to the object for holding the data. Does that make sense or should i stay with the properties? Extra: Are there general pros and cons for the different approaches? And what keywords / concepts do i have to search for to find discussions about that somehow general question? Thanks in advance

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  • Problem in reading configuration file from Class library project

    - by Newbie
    If I create an app.config file in a console apps like this <?xml version="1.0" encoding="utf-8" ?> <configuration> <appSettings> <add key ="key1" value ="val1"/> </appSettings> </configuration> and access the same from the console application like object sourcePath = System.Configuration.ConfigurationManager.AppSettings["key1"]; or by object sourcePath = System.Configuration.ConfigurationSettings.AppSettings["key1"]; I am able to get the value. But if I do the same thing in a class library project, I am getting a null value. Why? Where I am making mistake? I have added the proper reference System.Configuration. I am using C# 3.0

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  • System.NullReferenceException with WhoCanHelpMe Unit Test

    - by tlum
    I'm working with a test project based on WhoCanHelpMe, which is based on Sharp Architecture, NHibernateValidator, etc. As its written the when_the_profile_tasks_is_asked_to_create_a_profile unit test creates the profile object and saves it without issue. Now the profile object is a CreateProfileDetails type that derives from their own ValidatableValueObject which inherits the IValidatable interface. The problem surfaces when my class is based on an Entity rather than their ValidatableValueObject. When the test is run a System.NullReferenceException because Validate() is null. I'm afraid that I'm at a loss to resolve this bad behavior. Does anyone have some suggestions to get to the bottom of this? Thanks, -Ted-

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  • Why is the value of __name__ changing after assignment to sys.modules[__name__]?

    - by martineau
    While trying to do something similar to what's in the ActiveState recipe titled Constants in Python by Alex Martelli, I ran into an unexpected side-effect that assigning a class instance to an entry in sys.modules apparently has in Python 2.7 -- namely that doing so apparent changes the value of __name__ to None as illustrated in the following code fragment: class _test(object): pass import sys print '__name__: %r' % __name__ # __name__: '__main__' sys.modules[__name__] = _test() print '__name__: %r' % __name__ # __name__: None if __name__ == '__main__': # never executes... import test print "done" I'd like to understand why this is happening. I don't believe it was that way in Python 2.6 and earlier versions since I have some older code where apparently the if __name__ == '__main__': conditional worked as expected following the assignment (but no longer does). FWIW, I also noticed that the name _class is getting rebound from a class object to None, too, after the assignment. Also seems odd to me that they're being rebound to 'None' rather than disappearing altogether... Update: I'd like to add that any workarounds for achieving the effect of if __name__ == '__main__':, given what happens would be greatly appreciated. TIA!

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  • How is Core Data detecting the conflicts, actually?

    - by brainfrog
    Apple says about -detectConflictsForObject: If on the next invocation of save: object has been modified in its persistent store, the save fails. This allows optimistic locking for unchanged objects. Conflict detection is always performed on changed or deleted objects. So what does this mean? If I simply modify an managed object and then save the context, there is always a conflict detection happening? Does this conflict detection simply compare the timestamps of the "records" to see if the "new" data is actually "old"? Is that a conflict?

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  • h:selectOneMenu not populating a 'selected' item

    - by dann.dev
    I'm having trouble with an h:selectOneMenu not having a selected item when there is already something set on the backing bean. I am using seam and have specified a customer converter. When working on my 'creation' page, everything works fine, something from the menu can be selected, and when the page is submitted, the correct value is assigned and persisted to the database as well. However when I work on my 'edit' page the menu's default selection is not the current selection. i have gone through and confirmed that something is definitely set etc. My selectOneMenu looks like this: <h:selectOneMenu id="selVariable" value="#{customer.variableLookup}" converter="#{variableLookupConverter}"> <s:selectItems var="source" value="#{customerReferenceHelper.variableLookups()}" label="#{source.name}" /> </h:selectOneMenu> And the converter is below. It very simple and just turns the id from string to int and back etc: @Name( "sourceOfWealthLookupConverter" ) public class SourceOfWealthLookupConverter implements Serializable, Converter { @In private CustomerReferenceHelper customerReferenceHelper; @Override public Object getAsObject( FacesContext arg0, UIComponent arg1, String arg2 ) { VariableLookup variable= null; try { if ( "org.jboss.seam.ui.NoSelectionConverter.noSelectionValue".equals( arg2 ) ) { return null; } CustomerReferenceHelper customerReferenceHelper = ( CustomerReferenceHelper ) Contexts.getApplicationContext().get( "customerReferenceHelper" ); Integer id = Integer.parseInt( arg2 ); source = customerReferenceHelper.getVariable( id ); } catch ( NumberFormatException e ) { log.error( e, e ); } return variable; } @Override public String getAsString( FacesContext arg0, UIComponent arg1, Object arg2 ) { String result = null; VariableLookup variable= ( VariableLookup ) arg2; Integer id = variable.getId(); result = String.valueOf( id ); return result; } } I've seen a few things about it possibly being the equals() method on the class, (that doesn't add up with everything else working, but I overrode it anyway as below, where the hashcode is just the id (id is a unique identifier for each item). Equals method: @Override public boolean equals( Object other ) { if ( other == null ) { return false; } if ( this == other ) { return true; } if ( !( other instanceof VariableLookup ) ) { return false; } VariableLookup otherVariable = ( VariableLookup ) other; if ( this.hashCode() == otherVariable.hashCode() ) { return true; } return false; } I'm at my wits end with this, I can't find what I could have missed?! Any help would be much appreciated

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  • PHP file modification time in milliseconds

    - by Steven Rosato
    I there, I am currently writing a unit test which asserts that a file did not get modified. The test code execution takes less than one second and therefore I would like to know if it is possible to retrieve the file modification time in milliseconds. filemtime() function returns the UNIX timestamp in seconds. My current solution is using the sleep(1) function which will assure me that 1 second passed before checking if it was modified or not. I don't like that solution since it slows down the test by a great deal. I cannot assert the content equality via get_file_contents() since the data that can be rewritten would be the same. I am guessing it is impossible, is it?

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  • When iterating over values, why does typeof(value) return "string" when value is a number? Javascrip

    - by Mark
    I'm using Google Chrome for this test: Contrary to intuition, the first loop alerts "string" 3 times, while the second loop alerts "number" 3 times. numarray = [1, 2, 3]; //for-each loop for(num in numarray) alert(typeof(num)); //standard loop for(i=0; i<numarray.length; i++) alert(typeof(numarray[i])); I was expecting both loops to alert "number" 3 times. How is the first loop implemented in Javascript? In other words, if the for-each is syntactic sugar, what is its equivalent using a standard loop? Also, is there some way to iterate over an object's namespace using a standard loop? I'm looking to touch every one of some object's methods and attributes using a loop of the second kind. I'm new to Javascript and any help is highly appreciated, thanks.

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  • ASP MVC Creating Form Rows Dynamically

    - by Jonathan Stowell
    Hi Guys, I haven't even attempted this yet and am creating this question for advice really. I have a strongly typed page which receives a form model composed of several components. It is to create a mitigating circumstance (MC) for a student at a university for my final year project. A MC can be composed of the initial problem, assessment extensions, and I use a multi select box to allow the user to select staff retrieved from the database which are able to view the MC once created. The thing is I feel that a student could be granted many assignment extensions for one problem. I am wander if it is possible to include a button/image on the form which when clicked will create a new assessment extension object, and duplicate the form components to set the values for the object? This would all need to occur without any page refreshes. Any advice, or links to good tutorials would be appreciated. I have so far been unable to find any suitable examples. Thanks, Jon

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  • What is an instance of a field called?

    - by waxwing
    This might be an odd question, but it has actually caused me some headache. In Object oriented programming, there are accepted names for key concepts. In our model, we have classes with methods and fields. Now, going to the data world: An instance of a class is called an object. An instance of a field is called... what? A value? Isn't the term value a little broad for this? I have been offered "property" as well, but isn't property also part of the model and not the data? (This is not purely academic, I am actually coding these concepts.)

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  • new MyClass(); vs new MyClass;

    - by Bytecode Ninja
    In some JavaScript code snippets (e.g. http://mckoss.com/jscript/object.htm) I have seen objects being created in this way: var obj = new Foo; However, at least at MDC, it seems that the parentheses are not optional when creating an object: var obj = new Foo(); Is the former way of creating objects valid and defined in the ECMA standard? Are there any differences between the former way of creating objects and the later? Is one preferred over the other? Thanks in advance.

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  • Application_EndRequest Dosent Fire on a 404

    - by Shane
    I am using ASP MVC 2 and Nhibernate. I have created an HTTP Module as demonstrated in Summer of NHibernate 13 that looks like so: public void Init(HttpApplication context) { context.PreRequestHandlerExecute += new EventHandler(Application_BeginRequest); context.PostRequestHandlerExecute += new EventHandler(Application_EndRequest); } private void Application_BeginRequest(object sender, EventArgs e) { ISession session = StaticSessionManager.OpenSession(); session.BeginTransaction(); CurrentSessionContext.Bind(session); } private void Application_EndRequest(object sender, EventArgs e) { ISession session = CurrentSessionContext.Unbind(StaticSessionManager.SessionFactory); if (session != null) try { session.Transaction.Commit(); } catch (Exception) { session.Transaction.Rollback(); } finally { session.Flush(); session.Close(); } } web.config <add name="UnitOfWork" type="HttpModules.UnitOfWork"/> My problem is that Application_EndRequest never gets called on a 404 error so if my view does not render I completely block database access until my flush takes place. I am fairly new to NHibernate so I am not sure if I am missing something.

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  • Mapping restful ajax requests to spring

    - by Diones
    I have this piece of code: @RequestMapping(value = "/test.json", method = RequestMethod.GET) @ResponseStatus(HttpStatus.OK) public @ResponseBody Object[] generateFile(@RequestParam String tipo) { Object[] variaveis = Variavel.getListVariavelByTipo(tipo); return variaveis; } As far as I know it should take a request to test.json?tipo=H and return the JSON representation of Variavel[], however when I make such request I get: HTTP Status 406 - type Status report message descriptionThe resource identified by this request is only capable of generating responses with characteristics not acceptable according to the request "accept" headers () By using the following function I can get the expected json: @RequestMapping(value = "/teste.json") public void testeJson(Model model, @RequestParam String tipo) { model.addAttribute("data", Variavel.getListVariavelByTipo("H")); } What I'm doing wrong?

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  • Stack around variable corrupted when using cvBlobsLib (OpenCV)

    - by jpromvi
    I am trying to do simple image processing with OpenCV and the cvBlobsLib in Visual C++ 2008, and I get an error message when I try to create a CBlobResult object IplImage* original = cvLoadImage("pic6.png",0); cvThreshold(original, original, 100, 255, CV_THRESH_BINARY); CBlobResult blobs = CBlobResult(original, NULL, 255); The message is the following: Run-Time Check Failure #2 - Stack around the variable blobs was corrupted Why does this happen? How should I create this object? Thank you very much for your help.

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  • Game network physics collision

    - by Jonas Byström
    How to simulating two client-controlled vehicles colliding (sensibly) in a typical client/server setup for a network game? I did read this eminent blog post on how to do distributed network physics in general (without traditional client prediction), but this question is specifically on how to handle collisions of owned objects. Example Say client A is 20 ms ahead of server, client B 300 ms ahead of server (counting both latency and maximum jitter). This means that when the two vehicles collide, both clients will see the other as 320 ms behind - in the opposite direction of the velocity of the other vehicle. Head-to-head on a Swedish highway means a difference of 16 meters/17.5 yards! What not to try It is virtually impossible to extrapolate the positions, since I also have very complex vehicles with joints and bodies all over, which in turn have linear and angular positions, velocities and accelerations, not to mention states from user input.

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  • living column in instruments

    - by dubbeat
    In the context of allocations what exactly does the living column mean? Does it mean the number of times an object was created or does it mean how many instances of an object there is? I ask because I'm testing going in and out of a view. When I enter the view I create a class "myClass". When I exit the view I nil "myClass" and release it. If I go in and out of the view 6 times for example the living column in instruments for "myClass" says 6. Is this normal or is it not being released properly?

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  • Rails easy shop

    - by ciss
    I have some question about data organization in my shop. So, after easy mind hacking i decide to create three models: Item, Property and PropertyType Item: id,property_id Property: id, data, property_type_id #(data, serialized object with something like what: {:color => "red", :price => 1000} PropertyType: id, data #(data, also serialized object with {:color => :string, :price => :fixnum}) So, does this good or bad idea? I predict what I can find some problems with validations. But I really need some fields created by user via admin-panel (now I'm talking about Item Properties, which can be changed in any time)

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  • What is the best way to make a game timer in Actionscript 3?

    - by Nuthman
    I have built an online game system that depends on a timer that records how long it took a player to complete a challenge. It needs to be accurate to the millisecond. Their time is stored in a SQL database. The problem is that when I use the Timer class, some players are ending up getting scores in the database of less than a second. (which is impossible, as most challenges would take at least 11 seconds to complete even in a perfect situation.) What I have found is that if a player has too many browser windows open, and/or a slow computer, the flash game slows down actually affecting the timer speed itself. The timer is 'spinning' on screen so you can physically see the numbers slowing down. It is frustrating that I cannot just open a second thread or do something to allow flash to keep accurate time regardless of whatever else is going on in the program. Any ideas?

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  • Java LinkedList iterator being exhausted prematurely

    - by Sujeet
    I am using LinkedList and retrieving an Iterator object by using list.iterator(). After that, I am checking it.hasNext(), real issue is while checking it.hasNext(), sometimes it returns false. I need help why this is happening, though I have elements in the list. Some code: public synchronized void check(Object obj) throws Exception { Iterator itr = list.iterator(); while(itr.hasNext()) { //This Line I get false.. though i have list size is 1 Item p = (Item)itr.next(); if(p.getId() == null) {continue;} if(p.getId().getElemntId() == obj.getId() || obj.getId() == 0 ) { p.setResponse(obj); notifyAll(); return; } } Log.Error("validate failed obj.getId="+obj.getId()+" **list.size="+list.size()*This shows 1*); throw new Exception("InvalidData"); }

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  • Is there a "concise" way to do namespacing in JavaScript?

    - by olliej
    I've frequently encountered sites that put all of their javascript inside a "namespace" structure along the lines of namespaces = { com : { example: { example.com's data} } But setting this up safely with respect to other namespaced frameworks seems to require a relatively hefty amount of code (defined as 2 lines). I was wondering whether anyone knows of a concise way to do this? and whether there's a relatively standard/consistent way to structure it? eg. is the "com" namespace directly attached to the global object, or is it attached through a namespace object? [Edit: whoops, obviously {com = { ... } } wouldn't accomplish anything close to what i intended, thanks to Shog9 for pointing that out. :D]

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  • Compiler error when using abstract types

    - by Dylan
    I'm trying to implement a "protocol helper" trait that is responsible for matching up Prompts and Responses. The eventual goal is to have an object that defines the various Prompt and Response classes as subclasses of a sealed trait, then have a class that mixes in the ProtocolSupport trait for that Protocol object. The problem is that my current approach won't compile, even though I'm fairly sure it should. Here's a distilled version of what I've got: trait Protocol { type Response type Prompt <: BasePrompt trait BasePrompt { type Data def validate(response: Response): Validated[Data] } } trait ProtocolSupport[P <: Protocol] { def foo(prompt: P#Prompt, response: P#Response) = { // compiler error prompt.validate(response) } } The compiler doesn't like the response as an argument to prompt.validate: [error] found : response.type (with underlying type P#Response) [error] required: _4.Response where val _4: P [error] prompt.validate(response) [error] ^ This isn't very helpful.. it seems to say that it wants a P.Response but that's exactly what I'm giving it, so what's the problem?

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  • How is a constructor executed?

    - by simion
    I am doing some reviison from the lecture slides and it says a constructor is executed in the following way; If the constructor starts with this, recursively execute the indicated constructor, then go to step 4. Invoke the explicitly or implicitly indicated superclass constructor (unless this class is java.lang.Object) Initialise the fields of the object in the order in which they were declared in this class Execute the rest of the body of this constructor. What i dont undertsand is that, a constructor can never "start" with this, because even if it forms no class heirarchy/relationship then super() is inserted by default. How would this fit in with the description above? Thanks

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  • Javascript Pointers question with Dates

    - by Mega Matt
    I noticed this situation in my code (unfortunately), and was able to duplicate it in my own JS file. So I have this code: var date1 = new Date(); // today var date2 = date1; date2 = date2.setDate(date2.getDate() + 1); // what is date1? After this code executes, date1 is today's date + 1! This harkens back to my undergrad days when I learned about pointers, and I guess I'm a little rusty. Is that what's happening here? Obviously I've moved the assignment away from date1, and am only modifying date2, but date1 is being changed. Why is this the case? Incidentally, after this code executes date2 is a long number like 1272123603911. I assume this is the number of seconds in the date, but shouldn't date2 still be a Date object? setDate() should return a Date object... Thanks for the help.

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  • TDBGrid columns design time or run time?

    - by Mawg
    I am using TDBGrid for the first time. I didn't even notice the Columns property in the object inspector and everything went just fine: the grid was filled. Then I saw the Columns property and tried it. When I use the object insector to add items to the Columns property of the grid, they do not all of them show up at run time. To me, it looks like the FieldName property is important. It looks like it is correct, but there are no values in some columns. If I leave this property blank (no columns at all) it seems that the control populates it itself at run time and I do see all the columns. I could live with that. When I set column titles at run time it works, but setting column width does not.

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