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• correct technical term for this pattern

  - by Oliver A.

  sometimes I use a pattern which is very similar to the singleton pattern: There is one default instance which and a static get method to aces it. But you may create other instances and pass it as optional parameter and if you want to and you can even replace the default instance with a instance from a child class. So it is NO SINGLETON at all but it is used like one singleton in most cases. Anyone got an idea who to call something like this ? Maybe half*** singleton? domiton?

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• Showing a hidden form

  - by Arcadian

  Newb question: how do i show a from that have been hidden using this.Hide(); I have tried MainMenuForm.Show(); and this just says i need an object ref have tried: MainMenuForm frmMainMenu = new MainMenuForm(); frmMainMenu.Show(); which seems to show the appropriate form. but when you exit the app, it is still held in memory because it hasn't shown the form that was hidden, instead it has shown a new version of the form. in effect having 2 instances of the form (one hidden, one visible). whats the correct procedure here Thanks in advance

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• Why is the Dependency Property not returning its value?

  - by B-Rad

  I have a MyUserControl with the following Xaml: <TextBox Text="{Binding InputValueProperty}" /> In the MyUserControl.xaml.cs I have: public string InputValue { get { return (string)GetValue(InputValueProperty); } set { SetValue(InputValueProperty, value); } } public static readonly DependencyProperty InputValueProperty = DependencyProperty.Register("InputValueProperty", typeof(string), typeof(MyUserControl)); In my MainWindow.xaml I create a user control: <local:MyUserControl InputValue="My Input" /> Later on in my MainWindow.xaml.cs I am trying to access this string. All instances of MyUserControl are contained in a List and I access them with a foreach. string temp = userControl.InputValue; This is always null. In my MainWindow.xaml I can see the "My Input" in the text box of the user control but I can't ever seem to get it out of there.

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• Javascript Inheritance and Arrays

  - by Inespe

  Hi all! I am trying to define a javascript class with an array property, and its subclass. The problem is that all instances of the subclass somehow "share" the array property: // class Test function Test() { this.array = []; this.number = 0; } Test.prototype.push = function() { this.array.push('hello'); this.number = 100; } // class Test2 : Test function Test2() { } Test2.prototype = new Test(); var a = new Test2(); a.push(); // push 'hello' into a.array var b = new Test2(); alert(b.number); // b.number is 0 - that's OK alert(b.array); // but b.array is containing 'hello' instead of being empty. why? As you can see I don't have this problem with primitive data types... Any suggestions?

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• What's the point of indicating AllowMultiple=false on an abstract Attribute class?

  - by tvanfosson

  On a recent question about MVC attributes, someone asked whether using HttpPost and HttpDelete attributes on an action method would result in either request type being allowed or no requests being allowed (since it can't be both a Post and a Delete at the same time). I noticed that ActionMethodSelectorAttribute, from which HttpPostAttribute and HttpDeleteAttribute both derive is decorated with [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)] I had expected it to not allow both HttpPost and HttpDelete on the same method because of this, but the compiler doesn't complain. My limited testing tells me that the attribute usage on the base class is simply ignored. AllowMultiple seemingly only disallows two of the same attribute from being applied to a method/class and doesn't seem to consider whether those attributes derive from the same class which is configured to not allow multiples. Moreover, the attribute usage on the base class doesn't even preclude your from changing the attribute usage on a derived class. That being the case, what's the point of even setting the values on the base attribute class? Is it just advisory or am I missing something fundamental in how they work? FYI - it turns out that using both basically precludes that method from ever being considered. The attributes are evaluated independently and one of them will always indicate that the method is not valid for the request since it can't simultaneously be both a Post and a Delete.

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• Is there a way to automatically update application on Android?

  - by Levara

  Hi, I'm developing an application that will most likely be preinstalled on devices. It will be also available on Market. Is there a way to update those instances that are not downloaded through Market, since Market won't notify users about an update. I was thinking about, as suggested here, trying to contact my site periodically, and when update is available, download it. I'm wondering if there is a way to do this update automatically, so that user doesn't have to do anything (like running the package manually). Or, when my site shows update is available, to offer users an update through Market, even though it's not installed through Market. Thanks!

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• Using non-Railsy route to prepopulate a form

  - by user94154

  I have many instances of a Rails model, Post. When viewing an individual post, I'd like to create a form to create a child of Post called Comment. I'd like to prepopulate this form with a hidden tag that contains the post_id which is the foreign key in Comment. The Railsy way to do this is to create a fancy-ish route such as: /comments/new/post/:post_id However, this gunks up the routes file and doesn't leave much flexibility. Let's say I want to create a link somewhere else that prepopulates a different attribute of the form...then I'd have to add another route for this. So I think I'm going to create urls like this on /posts/show/:id: /comments/new?comment[post_id]=<%= @post.id %> This way I can add any other attributes as I need. I know the plus side associated with this, now what are the downsides?

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• Updating a database periodically with Java

  - by MSR

  I would like to perform updates to a MySQL database using two separate classes (that do different things) -- one doing so every 10 seconds, and the second every minute. I have a few gaps in my Java knowledge and I'm wondering what the best way to achieve it is. Importantly, if connectivity to the database is lost, I need reconnection attempts to occur indefinitely, and I'm guessing the use of Prepared Statements will make queries more efficient. Should the connection to the database be left open all the time or closed between the updates being run? Maybe I also need to think about clearing objects/resources out of memory if the class instances are going to be run indefinitely.

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• How do you create a generic method in a class?

  - by Seth Spearman

  Hello, I am really trying to follow the DRY principle. I have a sub that looks like this? Private Sub DoSupplyModel OutputLine("ITEM SUMMARIES") Dim ItemSumms As New SupplyModel.ItemSummaries(_currentSupplyModel, _excelRows) ItemSumms.FillRows() OutputLine("") OutputLine("NUMBERED INVENTORIES") Dim numInvs As New SupplyModel.NumberedInventories(_currentSupplyModel, _excelRows) numInvs.FillRows() OutputLine("") End Sub I would like to collapse these into a single method using generics. For the record, ItemSummaries and NumberedInventories are both derived from the same base class DataBuilderBase. I can't figure out the syntax that will allow me to do ItemSumms.FillRows and numInvs.FillRows in the method. FillRows is declared as Public Overridable Sub FillRows in the base class. Thanks in advance. EDIT Here is my end result Private Sub DoSupplyModels() DoSupplyModelType("ITEM SUMMARIES",New DataBlocks(_currentSupplyModel,_excelRows) DoSupplyModelType("DATA BLOCKS",New DataBlocks(_currentSupplyModel,_excelRows) End Sub Private Sub DoSupplyModelType(ByVal outputDescription As String, ByVal type As DataBuilderBase) OutputLine(outputDescription) type.FillRows() OutputLine("") End Sub But to answer my own question...I could have done this... Private Sub DoSupplyModels() DoSupplyModelType(Of Projections)("ITEM SUMMARIES") DoSupplyModelType(Of DataBlocks)("DATA BLOCKS") End Sub Private Sub DoSupplyModelType(Of T as DataBuilderBase)(ByVal outputDescription As String, ByVal type As T) OutputLine(outputDescription) dim type as New T(_currentSupplyModel,_excelRows) type.FillRows() OutputLine("") End Sub Is that right? Does the New T() work? Seth

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• The most efficient way to calculate an integral in a dataset range

  - by Annalisa

  I have an array of 10 rows by 20 columns. Each columns corresponds to a data set that cannot be fitted with any sort of continuous mathematical function (it's a series of numbers derived experimentally). I would like to calculate the integral of each column between row 4 and row 8, then store the obtained result in a new array (20 rows x 1 column). I have tried using different scipy.integrate modules (e.g. quad, trpz,...). The problem is that, from what I understand, scipy.integrate must be applied to functions, and I am not sure how to convert each column of my initial array into a function. As an alternative, I thought of calculating the average of each column between row 4 and row 8, then multiply this number by 4 (i.e. 8-4=4, the x-interval) and then store this into my final 20x1 array. The problem is...ehm...that I don't know how to calculate the average over a given range. The question I am asking are: Which method is more efficient/straightforward? Can integrals be calculated over a data set like the one that I have described? How do I calculate the average over a range of rows?

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• Are static members inherited? (C++)

  - by Keand64

  When static members are inherited, are they static for the entire heirarchy, or just that class, ie: class SomeClass { public: SomeClass(){total++;} static int total; }; class SomeDerivedClass: public SomeClass { public: SomeDerivedClass(){total++;} }; int main() { SomeClass A; SomeClass B; SomeDerivedClass C; return 0; } would total be 3 in all three instances, or would it be 2 for SomeClass and 1 for SomeDerivedClass?

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• iPhone view architecture question

  - by Joe

  So I have (for instance) three views: A: root view B: a view functionally identical to root C: a data entry view which collects a few piece of info What I'm trying to do is reuse C to supply the data it collects to either A or B. It should supply the data to whichever of the two it is pushed onto. The data for A is similar, but functionally distinct, to what collects for B. Right now, I'm passing data from C to A or B via a singleton class. What I'm trying to avoid is having two instances of C, one to supply data to A and B (because, in actuality, the program will have 5 total views like C. Does the question make sense?

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• How can I tell what is using the memory when there is a heap overflow in Java?

  - by Grae

  Hi all, I know a little about profiling, but what I am particularlly insterest in, is what has all the memory when I get these heap over flow exceptions. I will start getting them after about a hour of debugging. I am hoping there is some sort of dump or something, that I can use to get a list of what instances are around at the time the program starts. By the way, sorry if this is a lazy question. I really shoud put sometime in learning about profiling. Grae

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• Python to C# Conversion of RGBA values not working

  - by clangers

  I'm currently converting some python code to C#, and I'm having an issue with the RGBA C# libraries # Original Python Code: d = math.sqrt( (x - size/2.0)**2 + (y - size/2.0)**2 ) rgbVal = int(200*d/md + 50) rgba = (0,0,0, 255 - rgbVal) img.putpixel((x,y), rgba) // My C# Code double d = Math.Sqrt(Math.Pow((x - DotSize / 2.0), 2) + Math.Pow((y - DotSize / 2.0), 2)); int rgbVal = (int) (200 * d / md + 50); Color color = Color.FromArgb(255 - rgbVal, 0, 0, 0); // ** ERROR ** img.SetPixel(x,y, color); At both instances of the code d is equal to 106 and md is equal to 53. However the resulting rgbVal value is 450. This would obviously mean that 255 - 450 is -195, which causes an error to be thrown as each individual value must be between 0 and 255. Anyone have any idea how I can fix this. Please note that the data is the same when running both the python and C# versions.

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• How do I specify a dynamic position for the start of substring?

  - by analyticsPierce

  As in the example, I am trying to substring the Video_full column in a data.frame (video_data_2) I am working on. I want to keep all the characters after the period. The period is always present, there is only one period and it is in a different position in each value for the column. Date Video_full Instances 1 Apr 1, 2010 installs/AA.intro_video_1 546 2 Apr 1, 2010 installs/ABAC.intro_video_2 548 I got substring to work; video_data_2$Video_full <- substring(video_data_2$Video_full,11) And strsplit also; strsplit("installs/AA.intro_video_1 ",'[.]') I'm just not able to figure out how to start the substring in a dynamic position or only keep the second value returned by strsplit. Thanks for any help you can offer for a simple question.

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• How to customize file dialog in wpf

  - by ManjuAnoop

  In Windows7 I am using a customized Open File Dialog( WPF application). My Open File dialog is derived from Microsoft.Win32.CommonDialog. The dialog have old look, how to change this to new look (windows7 file dialog look(Explorer style)). Code portion: private const int OFN_ENABLESIZING = 0x00800000; private const int OFN_EXPLORER = 0x00080000; private const int OFN_ENABLEHOOK = 0x00000020; protected override bool RunDialog(IntPtr hwndOwner) { OPENFILENAME_I.WndProc proc = new OPENFILENAME_I.WndProc(this.HookProc); OPENFILENAME_I ofn = new OPENFILENAME_I(); this._charBuffer = CharBuffer.CreateBuffer(0x2000); if (this._fileNames != null) { this._charBuffer.PutString(this._fileNames[0]); } ofn.lStructSize = Marshal.SizeOf(typeof(OPENFILENAME_I)); ofn.hwndOwner = hwndOwner; ofn.hInstance = IntPtr.Zero; ofn.lpstrFilter = MakeFilterString(this._filter, this.DereferenceLinks); ofn.nFilterIndex = this._filterIndex; ofn.lpstrFile = this._charBuffer.AllocCoTaskMem(); ofn.nMaxFile = this._charBuffer.Length; ofn.lpstrInitialDir = this._initialDirectory; ofn.lpstrTitle = this._title; ofn.Flags = OFN_EXPLORER | OFN_ENABLESIZING | OFN_ENABLEHOOK; ofn.lpfnHook = proc; ofn.FlagsEx = 0x1000000 ; NativeMethods.GetOpenFileName(ofn); // } [SecurityCritical, SuppressUnmanagedCodeSecurity, DllImport("comdlg32.dll", CharSet = CharSet.Unicode, SetLastError = true)] internal static extern bool GetOpenFileName([In, Out] OPENFILENAME_I ofn);

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• Accessing primitive properties from objects stored in a NSDictionary

  - by ChrisS

  Apologies if this is a basic question, I am just starting with Objective-C and trying to wrap things around in my head! I have a simple class of the form: @interface Whatever : NSObject { int somePrimitive; SomeObject* someObject; } @property (nonatomic) int somePrimitive; @property (nonatomic, retain) SomeObject* someObject; The class is more involved that this, but this illustrates the purpose. When I store instances of this class in a NSMutableDictionary: Whatever *whatever = [[Whatever alloc] init]; whatever.somePrimitive = 1; whatever.someObject = ...; [myDictionary setObject:whatever forKey:@"someKey"]; and then try to retrieve the object later: Whatever *result = [myDictionary valueForKey:@"someKey"]; then, result.someObject is ok to reference but, result.somePrimitive crashes. Does the NSDictionary not copy over the primitives of the object? Is the rule that the object stored in a dictionary should only contain objects?

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• Is MSDN referencing a system.thread, a worker thread, an io thread or all three?

  - by w0051977

  Please see the warning below taken from the StreamWriter class specification (http://msdn.microsoft.com/en-us/library/system.io.streamwriter.aspx): "Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe." I understand that a W3WC process contains two thread pools i.e. worker threads and I/O threads. A worker thread could contain many threads of its own (if the application creates its own System.Thread instances). Does the warning only relate to System.Threads or does it relate to worker threads and I/O threads as well I.e. as the instance variables of the streamwriter class are not thread safe then does this mean that there would be problems if multiple worker threads access it eg if two users on two different web clients attempt to write to the log file at the same time, then could one lock out the other?

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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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• How do I write a Guice Provider that doesn't explicitly create objects?

  - by ripper234

  Say I have a ClassWithManyDependencies. I want to write a Guice Provider for this class, in order to create a fresh instance of the class several times in my program (another class will depend on this Provider and use it at several points to create new instances). One way to achieve this is by having the Provider depend on all the dependencies of ClassWithManyDependencies. This is quite ugly. Is there a better way to achieve this? Note - I certainly don't want the Provider to depend on the injector. Another option I considered is having ClassWithManyDependencies and ClassWithManyDependenciesProvider extend the same base class, but it's butt ugly.

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• Three customer addresses in one table or in separate tables?

  - by DR

  In my application I have a Customer class and an Address class. The Customer class has three instances of the Address class: customerAddress, deliveryAddress, invoiceAddress. Whats the best way to reflect this structure in a database? The straightforward way would be a customer table and a separate address table. A more denormalized way would be just a customer table with columns for every address (Example for "street": customer_street, delivery_street, invoice_street) What are your experiences with that? Are there any advantages and disadvantages of these approaches?

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• python-wordmatching

  - by challarao

  Write two functions, called countSubStringMatch and countSubStringMatchRecursive that take two arguments, a key string and a target string. These functions iteratively and recursively count the number of instances of the key in the target string. You should complete definitions for def countSubStringMatch(target,key): and def countSubStringMatchRecursive (target, key): For the remaining problems, we are going to explore other substring matching ideas. These problems can be solved with either an iterative function or a recursive one. You are welcome to use either approach, though you may find iterative approaches more intuitive in these cases of matching linear structures.

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• What is the difference between these two ways of creating NSStrings?

  - by adame

  NSString *myString = @"Hello"; NSString *myString = [NSString stringWithString:@"Hello"]; I understand that using method (1) creates a pointer to a string literal that is defined as static memory (and cannot be deallocated) and that using (2) creates an NSString object that will be autoreleased. Is using method (1) bad? What are the major differences? Is there any instances where you would want to use (1)? Is there a performance difference? P.S. I have searched extensively on Stack Overflow and while there are questions on the same topic, none of them have answers to the questions I have posted above.

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• Mysql SELECT with an OR across 2 columns

  - by Haroldo

  I'm creating a 'similar items' link table. i have a 2 column table. both columns contains product ids. The table is showing that these items are similar. However ids in the left column are more valuable. Say i want to select similar items to product '125b'. i only want 3 similar items to 125b. If there are any instances of 125b in col1 I would prefer these to finding 125b in col2. so i need a select statement along the lines of SELECT * FROM similar_items WHERE col_1={$id} OR col_2={$id} ORDER BY column(?) LIMIT 3 i do not want to do 2 separate queries ( ie query 2 if count(query1) <3 )

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• What db fits me?

  - by afvasd

  Dear Everyone I am currently using mysql. I am finding that my schema is getting incredibly complicated. I seek to find a new db that will suit my needs: Let's assume I am building a news aggregrator (which collects news from multiple website). I then run algorithms to determine if two news from different sites are actually referring to the same topic. I run this algorithm to cluster news together. The relationship is depicted below: cluster \--news1 \--word1 \--word2 \--news2 \--word3 \--news3 \--word1 \--word3 And then I will apply some magic and determine the importance of each word. Summing all the importance of each word gives me the importance of a news article. Summing the importance of each news article gives me the importance of a cluster. Note that above cluster there are also subgroups( like split by region etc), and categories (like sports, etc) which I have to determine the importance of that in a particular day per se. I have used views in the past to do so, but I realized that views are very slow. So i will normally do an insert into an actual table and index them for better performance. As you can see this leads to multiple tables derived like (cluster, importance), (news, importance), (words, importance) etc which can get pretty messy. Also the "importance" metric will change. It has become increasingly difficult to alter tables, update data (which I am using TRUNCATE TABLE) and then inserting from null. I am currently looking into something schemaless like Mongodb. I do not need distributedness. I would very much want something that is reasonably fast (which can be indexed) and something that is a lot more flexible that traditional RDMBS. Also, I need something that has some kind of ORM because I personally like ORM a lot. I am currently using sqlalchemy Please help!

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