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  • Ruby - Immutable Objects

    - by Chris Bunch
    I've got a highly multithreaded app written in Ruby that shares a few instance variables. Writes to these variables are rare (1%) while reads are very common (99%). What is the best way (either in your opinion or in the idiomatic Ruby fashion) to ensure that these threads always see the most up-to-date values involved? Here's some ideas so far that I had (although I'd like your input before I overhaul this): Have a lock that most be used before reading or writing any of these variables (from Java Concurrency in Practice). The downside of this is that it puts a lot of synchronize blocks in my code and I don't see an easy way to avoid it. Use Ruby's freeze method (see here), although it looks equally cumbersome and doesn't give me any of the synchronization benefits that the first option gives. These options both seem pretty similar but hopefully anyone out there will have a better idea (or can argue well for one of these ideas). I'd also be fine with making the objects immutable so they aren't corrupted or altered in the middle of an operation, but I don't know Ruby well enough to make the call on my own and this question seems to argue that objects are highly mutable.

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  • Setting specified flags before serializing objects

    - by Bernard
    We have a schema that we serialize and deserialize into an object hierarchy. Some elements are optional in the schema. The xsd tool creates a cs file that inserts a property for each optional element. This property ends in "Specified", i.e. nameSpecified tells the serializer and deserializer to include the optional "name" element when processing. I'm trying to write a method that rips through the object hierarchy using reflection and if a property has a value and it has a "Specified" corresponding property, I want to set the Specified property to true. I've tried to do this using reflection, ie. foreach(PropertyInfo p in MyObject.GetType().GetNestedTypes().GetType().GetProperties() { if the field name ends in Specified check if there is a field with the same name without Specied. If there is, and that field name has a value, then set the field name that ends in Specified to true; } Its the middle bit that I'm having trouble with. I preferably don't want to rip through the hierarchy and create a list of properties ending in Specified and then rip through it again to see if the corresponding name without the ending "Specified" exists and then check if it has a value. And the rip through it again to update all the Specified fields to true. Seems a bit of a long way around :( Anyone have any bright ideas?

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  • COM access to classic ASP intrinsic objects

    - by wrench
    I'm converting a VB6 COM object that works with classic ASP to a c# .Net COM Object Interop_COMSVCS.ObjectContext objContext; Interop_COMSVCS.AppServer objAppServer; objAppServer = null; // need to initialize before using objAppServer = new Interop_COMSVCS.AppServer(); objContext = objAppServer.GetObjectContext(); oApplication = (Interop_ASP.Application)objContext["Application"]; oSession = (Interop_ASP.Session)objContext["Session"]; oResponse = (Interop_ASP.Response)objContext["Response"]; oRequest = (Interop_ASP.Request)objContext["Request"]; oSession works to store local information to.from ASP storage oResponse can do simple writes to the browser BUT any code like oRequest.Cookies["sessionId"] or oResponse.Cookies["sessionId"] doesn't provide any sort of read or write access. Any cast or conversion I trry to do tells me I'm dealing with an empty or null System Object. There doesn't seem to be any sort of syntax to get/set the cookie collection. With COM+ I've seesn soem articles that indcate a switch for Access to ASP Intrinsic Objects -- that seesm to describe my issue, but I'd rather not use COM+. There are also some articles that indicate if I was using ASP.NET I could use HttpContext and HttpRequest/Response, but that's a completely different set of data objects that don't seem to be available with classic ASP. I've been stuck on this fopr a few days. Any help appreciated.

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  • Compare new Integer Objects in ArrayList Question

    - by thechiman
    I am storing Integer objects representing an index of objects I want to track. Later in my code I want to check to see if a particular object's index corresponds to one of those Integers I stored earlier. I am doing this by creating an ArrayList and creating a new Integer from the index of a for loop: ArrayList<Integer> courseselectItems = new ArrayList(); //Find the course elements that are within a courseselect element and add their indicies to the ArrayList for(int i=0; i<numberElementsInNodeList; i++) { if (nodeList.item(i).getParentNode().getNodeName().equals("courseselect")) { courseselectItems.add(new Integer(i)); } } I then want to check later if the ArrayList contains a particular index: //Cycle through the namedNodeMap array to find each of the course codes for(int i=0; i<numberElementsInNodeList; i++) { if(!courseselectItems.contains(new Integer(i))) { //Do Stuff } } My question is, when I create a new Integer by using new Integer(i) will I be able to compare integers using ArrayList.contains()? That is to say, when I create a new object using new Integer(i), will that be the same as the previously created Integer object if the int value used to create them are the same? I hope I didn't make this too unclear. Thanks for the help!

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  • Perl OO frameworks and program design - Moose and Conway's inside-out objects (Class::Std)

    - by Emmel
    This is more of a use-case type of question... but also generic enough to be more broadly applicable: In short, I'm working on a module that's more or less a command-line wrapper; OO naturally. Without going into too many details (unless someone wants them), there isn't a crazy amount of complexity to the system, but it did feel natural to have three or four objects in this framework. Finally, it's an open source thing I'll put out there, rather than a module with a few developers in the same firm working on it. First I implemented the OO using Class::Std, because Perl Best Practices (Conway, 2005) made a good argument for why to use inside-out objects. Full control over what attributes get accessed and so on, proper encapsulation, etc. Also his design is surprisingly simple and clever. I liked it, but then noticed that no one really uses this; in fact it seems Conway himself doesn't really recommend this anymore? So I moved to everyone's favorite, Moose. It's easy to use, although way way overkill feature-wise for what I want to do. The big, major downside is: it's got a slew of module dependencies that force users of my module to download them all. A minor downside is it's got way more functionality than I really need. What are recommendations? Inconvenience fellow developers by forcing them to use a possibly-obsolete module, or force every user of the module to download Moose and all its dependencies? Is there a third option for a proper Perl OO framework that's popular but neither of these two?

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  • LINQ to SQL - Tracking New / Dirty Objects

    - by Joseph Sturtevant
    Is there a way to determine if a LINQ object has not yet been inserted in the database (new) or has been changed since the last update (dirty)? I plan on binding my UI to LINQ objects (using WPF) and need it to behave differently depending whether or not the object is already in the database. MyDataContext context = new MyDataContext(); MyObject obj; if (new Random().NextDouble() > .5) obj = new MyObject(); else obj = context.MyObjects.First(); // How can I distinguish these two cases? The only simple solution I can think of is to set the primary key of new records to a negative value (my PKs are an identity field and will therefore be set to a positive integer on INSERT). This will only work for detecting new records. It also requires identity PKs, and requires control of the code creating the new object. Is there a better way to do this? It seems like LINQ must be internally tracking the status of these objects so that it can know what to do on context.SubmitChanges(). Is there some way to access that "object status"? Clarification Apparently my initial question was confusing. I'm not looking for a way to insert or update records. I'm looking for a way, given any LINQ object, to determine if that object has not been inserted (new) or has been changed since its last update (dirty).

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  • asp.net mvc - How to create fake test objects quickly and efficiently

    - by Simon G
    Hi, I'm currently testing the controller in my mvc app and I'm creating a fake repository for testing. However I seem to be writing more code and spending more time for the fakes than I do on the actual repositories. Is this right? The code I have is as follows: Controller public partial class SomeController : Controller { IRepository repository; public SomeController(IRepository rep) { repository = rep; } public virtaul ActionResult Index() { // Some logic var model = repository.GetSomething(); return View(model); } } IRepository public interface IRepository { Something GetSomething(); } Fake Repository public class FakeRepository : IRepository { private List<Something> somethingList; public FakeRepository(List<Something> somethings) { somthingList = somthings; } public Something GetSomething() { return somethingList; } } Fake Data class FakeSomethingData { public static List<Something> CreateSomethingData() { var somethings = new List<Something>(); for (int i = 0; i < 100; i++) { somethings.Add(new Something { value1 = String.Format("value{0}", i), value2 = String.Format("value{0}", i), value3 = String.Format("value{0}", i) }); } return somethings; } } Actual Test [TestClass] public class SomethingControllerTest { SomethingController CreateSomethingController() { var testData = FakeSomethingData.CreateSomethingData(); var repository = new FakeSomethingRepository(testData); SomethingController controller = new SomethingController(repository); return controller; } [TestMethod] public void SomeTest() { // Arrange var controller = CreateSomethingController(); // Act // Some test here // Arrange } } All this seems to be a lot of extra code, especially as I have more than one repository. Is there a more efficient way of doing this? Maybe using mocks? Thanks

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  • TCL TDom: Looping through Objects

    - by pws5068
    Using TDom, I would like to cycle through a list of objects in the following format: <object> <type>Hardware</type> <name>System Name</name> <description>Basic Description of System.</description> <attributes> <vendor>Dell</vendor> <contract>MM/DD/YY</contract> <supportExpiration>MM/DD/YY</supportExpiration> <location>Building 123</location> <serial>xxx-xxx-xxxx</serial> <mac>some-mac-address</mac> </attributes> </object> <object> <type>Software</type> <name>Second Object</name> ... Then I use TDom to make a list of objects: set dom [dom parse $xml] set doc [$dom documentElement] set nodeList [$doc selectNodes /systems/object] So far I've done this to (theoretically) select every "Object" node from the list. How can I loop through them? Is it just: foreach node $nodeList { For each object, I need to retrieve the association of each attribute. From the example, I need to remember that the "name" is "System Name", "vendor" is "Dell", etc. I'm new to TCL but in other languages I would use an object or an associative list to store these. Is this possible? Can you show me an example of the syntax to select an attribute in this manner?

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  • Problem with Binding Multiple Objects on WPF

    - by Diego Modolo Ribeiro
    Hi, I'm developing a user control called SearchBox, that will act as a replacer for ComboBox for multiple records, as the performance in ComboBox is low for this scenario, but I'm having a big binding problem. I have a base control with a DependencyProperty called SelectedItem, and my SearchControl shows that control so that the user can select the record. The SearchControl also has a DependencyProperty called SelectedItem on it, and it is being updated when the user selects something on the base control, but the UI, wich has the SearchControl, is not being updated. I used a null converter so that I could see if the property was updating, but it's not. Below is some of the code: This is the UI: <NectarControles:MaskedSearchControl x:Name="teste" Grid.Row="0" Grid.Column="1" Height="21" ItemsSource="{Binding C001_Lista}" DisplayMember="C001_Codigo" Custom:CustomizadorTextBox.CodigoCampo="C001_Codigo" ViewType="{x:Type C001:C001_Search}" ViewModelType="{x:Type C001_ViewModel:C001_ViewModel}" SelectedItem="{Binding Path=Instancia.C001_Holding, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource DebuggingConverter}}"> </NectarControles:MaskedSearchControl> This is the relevante part of the SearchControl: Binding selectedItemBinding = new Binding("SelectedItem"); selectedItemBinding.Source = this.SearchControlBase; selectedItemBinding.Mode = BindingMode.TwoWay; selectedItemBinding.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged; this.SetBinding(SelectedItemProperty, selectedItemBinding); ... public System.Data.Objects.DataClasses.IEntityWithKey SelectedItem { get { return (System.Data.Objects.DataClasses.IEntityWithKey)GetValue(SelectedItemProperty); } set { SetValue(SelectedItemProperty, value); if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("SelectedItem")); } } Please someone help me... Tks...

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  • Passing custom Python objects to nosetests

    - by Rob
    I am attempting to re-organize our test libraries for automation and nose seems really promising. My question is, what is the best strategy for passing Python objects into nose tests? Our tests are organized in a testlib with a bunch of modules that exercise different types of request operations. Something like this: testlib \-testmoda \-testmodb \-testmodc In some cases the test modules (i.e. testmoda) is nothing but test_something(), test_something2() functions while in some cases we have a TestModB class in testmob with the test_anotherthing1(), test_anotherthing2() functions. The cool thing is that nose easily finds both. Most of those test functions are request factory stuff that can easily share a single connection to our server farm. Thus we do a lot of test_something1(cnn), TestModB.test_anotherthing2(cnn), etc. Currently we don't use nose, instead we have a hodge-podge of homegrown driver scripts with hard-coded lists of tests to execute. Each of those driver scripts creates its own connection object. Maintaining those scripts and the connection minutia is painful. I'd like to take free advantage of nose's beautiful discovery functionality, passing in a connection object of my choosing. Thanks in advance! Rob P.S. The connection objects are not pickle-able. :(

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  • [C#] How can we differentiate between SDK class objects and custom class objects?

    - by Nayan
    To give an idea of my requirement, consider these classes - class A { } class B { string m_sName; public string Name { get { return m_sName; } set { m_sName = value; } } int m_iVal; public int Val { get { return m_iVal; } set { m_iVal = value; } } A m_objA; public A AObject { get { return m_objA; } set { m_objA = value; } } } Now, I need to identify the classes of the objects passed to a function void MyFunc(object obj) { Type type = obj.GetType(); foreach (PropertyInfo pi in type.GetProperties()) { if (pi.PropertyType.IsClass) { //I need objects only if (!type.IsGenericType && type.FullName.ToLower() == "system.string") { object _obj = pi.GetValue(obj, null); //do something } } } } I don't like this piece of code - if (!type.IsGenericType && type.FullName.ToLower() == "system.string") { because then i have to filter out classes like, System.Int16, System.Int32, System.Boolean and so on. Is there an elegant way through which I can find out if the object is of a class defined by me and not of system provided basic classes?

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  • Getting data from array of DataSet objects returned from web service

    - by Sarah Vessels
    I have a web service that I want to access when it is added as a web reference to my C# project. A particular method in the web service takes a SQL query string and returns the results of the query as a custom type. When I add the web service reference, the method shows up as returning DataSet[] instead of the custom type. This is fine provided I can still somehow access the data returned from the query within those DataSet objects. I ran a particular query that should return 6 rows; I got back a DataSet[] array with 6 elements. However, when I iterate over those DataSet objects, none of them has any tables (via the Tables property on the DataSet). What gives? Where is my data? The web service is tested and works when I use it as a data source in a Report Builder 2.0 report. I am able to send an XML SOAP query to the web service and get back XML results containing my data.

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  • NSString to NSURL objects

    - by user337844
    Hello, I have an array that I populated with my plist file, which looks something like this: <array> <string>http://www.apple.com</string> <string>http://www.google.com</string> <string>http://www.amazon.com</string> </array> So, I'm looking to convert these NSString objects to NSURL objects when I call them in my didSelectRowAtIndexPath method. Any ideas? This is what I have right now: - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSInteger row = [indexPath row]; if (self.viewController == nil) { TemplateViewController *details = [[TemplateViewController alloc] initWithNibName:@"TemplateViewController" bundle:nil]; self.viewController = details; [details release]; } NSString *tempURLString = [tieroneurlArray objectAtIndex:row]; NSURL *loadingUrl = [NSURL URLWithString:tempURLString]; [tieroneurlArray addObject:loadingUrl]; viewController.title = [NSString stringWithFormat:@"%@", [tieroneArray objectAtIndex:row]]; [self.viewController setTableURL:[tieroneurlArray objectAtIndex:row]]; TemplateAppAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; [delegate.templateNavController pushViewController:viewController animated:YES]; } And this is how I load the array with the plist: - (void)viewDidLoad { [super viewDidLoad]; NSString *path = [[NSBundle mainBundle] pathForResource:@"tier1Names" ofType:@"plist"]; tieroneArray = [[NSMutableArray alloc] initWithContentsOfFile:path]; NSString *tableURL = [[NSBundle mainBundle] pathForResource:@"tier1URL" ofType:@"plist"]; tieroneurlArray = [[NSMutableArray alloc] initWithContentsOfFile:tableURL]; }

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  • How do I store complex objects in javascript?

    - by Colen
    Hello, I need to be able to store objects in javascript, and access them very quickly. For example, I have a list of vehicles, defined like so: { "name": "Jim's Ford Focus", "color": "white", isDamaged: true, wheels: 4 } { "name": "Bob's Suzuki Swift", "color": "green", isDamaged: false, wheels: 4 } { "name": "Alex's Harley Davidson", "color": "black", isDamaged: false, wheels: 2 } There will potentially be hundreds of these vehicle entries, which might be accessed thousands of times. I need to be able to access them as fast as possible, ideally in some useful way. For example, I could store the objects in an array. Then I could simply say vehicles[0] to get the Ford Focus entry, vehicles[1] to get the Suzuki Swift entry, etc. However, how do I know which entry is the Ford Focus? I want to simply ask "find me Jim's Ford Focus" and have the object returned to me, as fast as possible. For example, in another language, I might use a hash table, indexed by name. How can I do this in javascript? Or, is there a better way? Thanks.

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  • List of objects or parallel arrays of properties?

    - by Headcrab
    The question is, basically: what would be more preferable, both performance-wise and design-wise - to have a list of objects of a Python class or to have several lists of numerical properties? I am writing some sort of a scientific simulation which involves a rather large system of interacting particles. For simplicity, let's say we have a set of balls bouncing inside a box so each ball has a number of numerical properties, like x-y-z-coordinates, diameter, mass, velocity vector and so on. How to store the system better? Two major options I can think of are: to make a class "Ball" with those properties and some methods, then store a list of objects of the class, e. g. [b1, b2, b3, ...bn, ...], where for each bn we can access bn.x, bn.y, bn.mass and so on; to make an array of numbers for each property, then for each i-th "ball" we can access it's 'x' coordinate as xs[i], 'y' coordinate as ys[i], 'mass' as masses[i] and so on; To me it seems that the first option represents a better design. The second option looks somewhat uglier, but might be better in terms of performance, and it could be easier to use it with numpy and scipy, which I try to use as much as I can. I am still not sure if Python will be fast enough, so it may be necessary to rewrite it in C++ or something, after initial prototyping in Python. Would the choice of data representation be different for C/C++? What about a hybrid approach, e.g. Python with C++ extension?

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  • Modeling related objects and their templates

    - by Duddle
    Hello everybody! I am having trouble correctly modeling related objects that can use templates. This is not homework, but part of a small project in the university. In this application the user can add several elements, which can either be passive or active. Each concrete element has different attributes, these must be set by the user. See diagram 1: Since the user will create many elements, we want there to be templates for each type of element, so some of the attributes are filled in automatically. See diagram 2: In my opinion, this is a bad design. For example, to get all possible templates for a PassiveElementA-object, there has to be a list/set somewhere that only holds PassiveElementATemplate-objects. There has to be a separate list for each subclass of Element. So if you wanted to add a new PassiveElement-child, you also have to edit the class which holds all these separate lists. I cannot figure out a good way to solve this problem. Since the concrete classes (i.e. PassiveElementA, ..., PassiveElementZ) have so many different attributes, many of the design patterns I know do not work. Thanks in advance for any hints, and sorry for my bad English.

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  • PHP: Array of objects is empty when I come to retrieve one from the array

    - by Tom
    Good morning, I am trying to load rows from a database and then create objects from them and add these objects to a private array. Here are my classes: <?php include("databaseconnect.php"); class stationItem { private $code = ''; private $description = ''; public function setCode($code ){ $this->code = $code; } public function getCode(){ return $this->code; } public function setDescription($description){ $this->description = $description; } public function getDescription(){ return $this->description; } } class stationList { private $stationListing; function __construct() { connect(); $stationListing = array(); $result = mysql_query('SELECT * FROM stations'); while ($row = mysql_fetch_assoc($result)) { $station = new stationItem(); $station->setCode($row['code']); $station->setDescription($row['description']); array_push($stationListing, $station); } mysql_free_result($result); } public function getStation($index){ return $stationListing[$index]; } } ?> As you can see I am creating a stationItem object per database row (which for now has a code and description) and I then push these on to the end of my array which is held as a private variable in stationList. This is code which creates this classes and attempts to access the properties on them: $stations = new stationList(); $station = $stations->getStation(0); echo $station->getCode(); I am finding that the sizeof($stationList) at the end of the constructor is 1 but then it is zero when we come to try to get an object from the array using the index. Therefore the error that I get is: Fatal error: Call to a member function getCode() on a non-object Please can someone explain to me why this is happening? I guess I am misunderstanding how object references work in PHP5.

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  • Deserializing XML to Objects in C#

    - by Justin Bozonier
    So I have xml that looks like this: <todo-list> <id type="integer">#{id}</id> <name>#{name}</name> <description>#{description}</description> <project-id type="integer">#{project_id}</project-id> <milestone-id type="integer">#{milestone_id}</milestone-id> <position type="integer">#{position}</position> <!-- if user can see private lists --> <private type="boolean">#{private}</private> <!-- if the account supports time tracking --> <tracked type="boolean">#{tracked}</tracked> <!-- if todo-items are included in the response --> <todo-items type="array"> <todo-item> ... </todo-item> <todo-item> ... </todo-item> ... </todo-items> </todo-list> How would I go about using .NET's serialization library to deserialize this into C# objects? Currently I'm using reflection and I map between the xml and my objects using the naming conventions.

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  • Having trouble animating Line in D3.js using and array of objects as data

    - by user1731245
    I can't seem to get an animated transition between line graphs when I pass in a new set of data. I am using an array of objects as data like this: [{ clicks: 40 installs: 10 time: "1349474400000" },{ clicks: 61 installs: 3 time: "1349478000000" }]; I am using this code to setup my ranges / axis's var xRange = d3.time.scale().range([0, w]), yRange = d3.scale.linear().range([h , 0]), xAxis = d3.svg.axis().scale(xRange).tickSize(-h).ticks(6).tickSubdivide(false), yAxis = d3.svg.axis().scale(yRange).ticks(5).tickSize(-w).orient("left"); var clicksLine = d3.svg.line() .interpolate("cardinal") .x(function(d){return xRange(d.time)}) .y(function(d){return yRange(d.clicks)}); var clickPath; function drawGraphs(data) { clickPath = svg.append("g") .append("path") .data([data]) .attr("class", "clicks") .attr("d", clicksLine); } function updateGraphs(data) { svg.select('path.clicks') .data([data]) .attr("d", clicksLine) .transition() .duration(500) .ease("linear") } I have tried just about everything to be able to pass in new data and see an animation between graph's. Not sure what I am missing? does it have something to do with using an array of objects instead of just a flat array of numbers as data?

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  • Most efficient way to check for DBNull and then assign to a variable?

    - by ilitirit
    This question comes up occasionally but I haven't seen a satisfactory answer. A typical pattern is (row is a DataRow): if (row["value"] != DBNull.Value) { someObject.Member = row["value"]; } My first question is which is more efficient (I've flipped the condition): row["value"] == DBNull.Value; // Or row["value"] is DBNull; // Or row["value"].GetType() == typeof(DBNull) // Or... any suggestions? This indicates that .GetType() should be faster, but maybe the compiler knows a few tricks I don't? Second question, is it worth caching the value of row["value"] or does the compiler optimize the indexer away anyway? eg. object valueHolder; if (DBNull.Value == (valueHolder = row["value"])) {} Disclaimers: row["value"] exists. I don't know the column index of the column (hence the column name lookup) I'm asking specifically about checking for DBNull and then assignment (not about premature optimization etc). Edit: I benchmarked a few scenarios (time in seconds, 10000000 trials): row["value"] == DBNull.Value: 00:00:01.5478995 row["value"] is DBNull: 00:00:01.6306578 row["value"].GetType() == typeof(DBNull): 00:00:02.0138757 Object.ReferenceEquals has the same performance as "==" The most interesting result? If you mismatch the name of the column by case (eg. "Value" instead of "value", it takes roughly ten times longer (for a string): row["Value"] == DBNull.Value: 00:00:12.2792374 The moral of the story seems to be that if you can't look up a column by it's index, then ensure that the column name you feed to the indexer matches the DataColumn's name exactly. Caching the value also appears to be nearly twice as fast: No Caching: 00:00:03.0996622 With Caching: 00:00:01.5659920 So the most efficient method seems to be: object temp; string variable; if (DBNull.Value != (temp = row["value"]) { variable = temp.ToString(); } This was a good learning experience.

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  • How are Scala closures transformed to Java objects?

    - by iguana
    I'm currently looking at closure implementations in different languages. When it comes to Scala, however, I'm unable to find any documentation on how a closure is mapped to Java objects. It is well documented that Scala functions are mapped to FunctionN objects. I assume that the reference to the free variable of the closure must be stored somewhere in that function object (as it is done in C++0x, e.g.). I also tried compiling the following with scalac and then decompiling the class files with JD: object ClosureExample extends Application { def addN(n: Int) = (a: Int) => a + n var add5 = addN(5) println(add5(20)) } In the decompiled sources, I see an anonymous subtype of Function1, which ought to be my closure. But the apply() method is empty, and the anonymous class has no fields (which could potentially store the closure variables). I suppose the decompiler didn't manage to get the interesting part out of the class files... Now to the questions: Do you know how the transformation is done exactly? Do you know where it is documented? Do you have another idea how I could solve the mystery?

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  • RegularExpression-esque search matching Objects in List

    - by Pindatjuh
    I'm currently working on an implementation of the following idea, and I was wondering if there is any literature on this subject. Working with Java, but the principle applies on any language with a decent type-system, I like to implement: matching Objects from a List using a RegularExpression-esque search: So let's say I have a List containing List<Object> x = new ArrayList<Object>(); x.add(new Object()); x.add("Hello World"); x.add("Second String"); x.add(5); // Integer (auto-boxing) x.add(6); // Integer Then I create a "Regular Expression" (not working with a stream of characters, but working with a stream of Objects), and instead of character-classes, I use type-system properties: [String][Integer] And this would match one sublist: {Match["Second String", 5]}. The expression: [String:length()<15] Will match two sublist (each of length 1) containing a String which instance is passing the expression instance.length() < 5: {Match["Hello World"],Match["Second String"]}. [Object][Object] Matches any pair in the List: {Match[Object,"Hello World"],Match["Second String", 5]}, in a streamed manner (no overlapping matches). Ofcourse, my implementation will have grouping, lookahead/lookbehinds and is hierarchical (i.e. matching n elements from Lists in Lists), etc. The above merely illustrates the concept. Is there a name for this principle, and is there literature available on it?

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  • Thread-safe initialization of function-local static const objects

    - by sbi
    This question made me question a practice I had been following for years. For thread-safe initialization of function-local static const objects I protect the actual construction of the object, but not the initialization of the function-local reference referring to it. Something like this: namspace { const some_type& create_const_thingy() { lock my_lock(some_mutex); static const some_type the_const_thingy; return the_const_thingy; } } void use_const_thingy() { static const some_type& the_const_thingy = create_const_thingy(); // use the_const_thingy } The idea is that locking takes time, and if the reference is overwritten by several threads, it won't matter. I'd be interested if this is safe enough in practice? safe according to The Rules? (I know, the current standard doesn't even know what "concurrency" is, but what about trampling over an already initialized reference? And do other standards, like POSIX, have something to say that's relevant to this?) For the inquiring minds: Many such function-local static const objects I used are maps which are initialized from const arrays upon first use and used for lookup. For example, I have a few XML parsers where tag name strings are mapped to enum values, so I could later switch over the tags enum values.

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  • Deep copy objects from different namespaces

    - by Wasim
    Hi all, I have the following situation: I have class User with the follwing properies : public class User { string user name ; List <Contact> contacts ; List <BookMark> book marks; . . . } I have the same class in a different namespace , with some different properties . BWT , it's the same situation of it's classes (Contact) and (BookMark). I need to make a deep copy of the same properties from the two classes . Actually , I arrive to this situation by having an Entity Framework edmx file . I created the first database (SQL server 2008) from this model . And copied he same edmx file to another project and created the database with SQL CE db. Now I get the first data model objects by WCF service and need to persist them in the local database in my application . The objects are the same but there are some changs because of the modeling issue with a different databse. Do you have any workarround about this assue. Thanks in advance ...

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  • Python: saving and loading objects and using pickle.

    - by Peterstone
    Hello, I´m trying to save and load objects using pickle module. First I declare my objects: >>> class Fruits:pass ... >>> banana = Fruits() >>> banana.color = 'yellow' >>> banana.value = 30 After that I open a file called 'Fruits.obj'(previously I created a new .txt file and I renamed 'Fruits.obj'): >>> import pickle >>> filehandler = open(b"Fruits.obj","wb") >>> pickle.dump(banana,filehandler) After do this I close my session and I began a new one and I put the next (trying to access to the object that it supposed to be saved): file = open("Fruits.obj",'r') object_file = pickle.load(file) But I have this message: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python31\lib\pickle.py", line 1365, in load encoding=encoding, errors=errors).load() ValueError: read() from the underlying stream did notreturn bytes I don´t know what to do because I don´t understand this message. Does anyone know How I can load my object 'banana'? Thank you! EDIT: As some of you have sugested I put: >>> import pickle >>> file = open("Fruits.obj",'rb') There were no problem, but the next I put was: >>> object_file = pickle.load(file) And I have error: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\Python31\lib\pickle.py", line 1365, in load encoding=encoding, errors=errors).load() EOFError

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