Search Results

Search found 18985 results on 760 pages for 'reference types'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 172/760 | < Previous Page | 168 169 170 171 172 173 174 175 176 177 178 179  | Next Page >

  • Describe the Damas-Milner type inference in a way that a CS101 student can understand

    - by user128807
    Hindley-Milner is a type system that is the basis of the type systems of many well known functional programming languages. Damas-Milner is an algorithm that infers (deduces?) types in a Hindley-Milner type system. Wikipedia gives a description of the algorithm which, as far as I can tell, amounts to a single word: "unification." Is that all there is to it? If so, that means that the interesting part is the type system itself not the type inference system. If Damas-Milner is more than unification, I would like a description of Damas-Milner that includes a simple example and, ideally, some code. Also, this algorithm is often said to do type inference. Is it really an inference system? I thought it was only deducing the types. Related questions: What is Hindley Miller? Type inference to unification problem

    Read the article

  • Putting update logic in your migrations

    - by Daniel Abrahamsson
    A couple of times I've been in the situation where I've wanted to refactor the design of some model and have ended up putting update logic in migrations. However, as far as I've understood, this is not good practice (especially since you are encouraged to use your schema file for deployment, and not your migrations). How do you deal with these kind of problems? To clearify what I mean, say I have a User model. Since I thought there would only be two kinds of users, namely a "normal" user and an administrator, I chose to use a simple boolean field telling whether the user was an adminstrator or not. However, after I while I figured I needed some third kind of user, perhaps a moderator or something similar. In this case I add a UserType model (and the corresponding migration), and a second migration for removing the "admin" flag from the user table. And here comes the problem. In the "add_user_type_to_users" migration I have to map the admin flag value to a user type. Additionally, in order to do this, the user types have to exist, meaning I can not use the seeds file, but rather create the user types in the migration (also considered bad practice). Here comes some fictional code representing the situation: class CreateUserTypes < ActiveRecord::Migration def self.up create_table :user_types do |t| t.string :name, :nil => false, :unique => true end #Create basic types (can not put in seed, because of future migration dependency) UserType.create!(:name => "BASIC") UserType.create!(:name => "MODERATOR") UserType.create!(:name => "ADMINISTRATOR") end def self.down drop_table :user_types end end class AddTypeIdToUsers < ActiveRecord::Migration def self.up add_column :users, :type_id, :integer #Determine type via the admin flag basic = UserType.find_by_name("BASIC") admin = UserType.find_by_name("ADMINISTRATOR") User.all.each {|u| u.update_attribute(:type_id, (u.admin?) ? admin.id : basic.id)} #Remove the admin flag remove_column :users, :admin #Add foreign key execute "alter table users add constraint fk_user_type_id foreign key (type_id) references user_types (id)" end def self.down #Re-add the admin flag add_column :users, :admin, :boolean, :default => false #Reset the admin flag (this is the problematic update code) admin = UserType.find_by_name("ADMINISTRATOR") execute "update users set admin=true where type_id=#{admin.id}" #Remove foreign key constraint execute "alter table users drop foreign key fk_user_type_id" #Drop the type_id column remove_column :users, :type_id end end As you can see there are two problematic parts. First the row creation part in the first model, which is necessary if I would like to run all migrations in a row, then the "update" part in the second migration that maps the "admin" column to the "type_id" column. Any advice?

    Read the article

  • Use WPF DLL Assembly in ASP.NET problem

    - by liimur
    Hello, I have C++ project that compiles as DLL Assembly in .NET 3.5 SP1 Project is used for Image rendering processing by using WPF (it loads 2 images from local folder, applies one image on another and saves the output file in the same folder). I want to use that that project as a reference in ASP.NET project to the rendering on the website. So I created simple Web Project in ASP.NET C# that uses C++ project as a Reference. Everything works great in ASP.NET Web Development Server (built-in Web server in VS2008). But once I publish this project to IIS on the same Machine or use IIS for debug instead of built-in Web server Image rendering it's not working anymore. I'm not getting any exceptions or error messages, it just output image is not processes as it supposed to be. If anyone know what could cause that I would really appreciate your insight!

    Read the article

  • When is #include <new> library required in C++?

    - by Czarak
    Hi, According to this reference entry for operator new ( http://www.cplusplus.com/reference/std/new/operator%20new/ ) : Global dynamic storage operator functions are special in the standard library: All three versions of operator new are declared in the global namespace, not in the std namespace. The first and second versions are implicitly declared in every translation unit of a C++ program: The header does not need to be included for them to be present. This seems to me to imply that the third version of operator new (placement new) is not implicitly declared in every translation unit of a C++ program and the header <new> does need to be included for it to be present. Is that correct? If so, how is it that using both g++ and MS VC++ Express compilers it seems I can compile code using the third version of new without #include <new> in my source code? Also, the MSDN Standard C++ Library reference entry on operator new gives some example code for the three forms of operator new which contains the #include <new> statement, however the example seems to compile and run just the same for me without this include? // new_op_new.cpp // compile with: /EHsc #include<new> #include<iostream> using namespace std; class MyClass { public: MyClass( ) { cout << "Construction MyClass." << this << endl; }; ~MyClass( ) { imember = 0; cout << "Destructing MyClass." << this << endl; }; int imember; }; int main( ) { // The first form of new delete MyClass* fPtr = new MyClass; delete fPtr; // The second form of new delete char x[sizeof( MyClass )]; MyClass* fPtr2 = new( &x[0] ) MyClass; fPtr2 -> ~MyClass(); cout << "The address of x[0] is : " << ( void* )&x[0] << endl; // The third form of new delete MyClass* fPtr3 = new( nothrow ) MyClass; delete fPtr3; } Could anyone shed some light on this and when and why you might need to #include <new> - maybe some example code that will not compile without #include <new> ? Thanks.

    Read the article

  • JavaScript Intellisene Problem?

    - by James Wiseman
    I've got an issue with JavaScript intellisense in Visual Web Developer 2008, which I'm starting to believe is "just one of those things", but thought I'd ask here just to check. I have a file MyOtherFile.js with a function GetRandomNumber() defined like so: function GetRandomNumber() { /// <summary> /// Summary description for GetRandomNumber /// </summary> return Math.random(); } When I reference this from another file, screen.js (/// <reference path="MyOtherFile.js" />) I get the intellisense as expected with the summary text as above. If, however, I call the function GetRandomNumber from within its own file (MyOtherFile.js) then I don't get the sumamry description. Any thoughts? Thanks.

    Read the article

  • Silverlight project builds in VS2008 but fails when using MSBuild

    - by Tom
    Hi, We have 2 Silverlight projects in the same solution; SLGlobalResource and SLData. SLData references SLGlobalResource (using references add reference projects). When we build it in debug within VS2008, everything builds fine and all is good. But when we build it using: msbuild TheSolution.sln /p:Configuration=Debug /t:rebuild SLData fails with the following error: ViewModels\ImportViewModel.cs : error CS0246: The type of name space "SLGlobalResource" could not be found (are you missing a using directive or an assembly reference?) This also happens in TeamCity (I guess because the TeamCity vs2008 runner uses MSBuild) Any ideas? Thanks Edit: There are actually 33 projects in total in the solution. I didn't think this was relevant before but now I'm thinking it could be - could this be a build order thing?

    Read the article

  • Web Service URL change is not recognized

    - by ila
    I deployed in a production environment a .net solution that consumes a web service added as "Service reference" in visual studio. Today the endpoint URL has changed, and I modified that URL in web.config. But when I run the solution I get the error: System.ServiceModel.FaultException: Server did not recognize the value of HTTP Header SOAPAction: http://93.62.150.200/LogEvent. Now that sound strange to me. As you can see, the IP is 93.62.... but the new value is different. The web.config entry (with the new value or the URL) is: <client> <endpoint address="http://213.92.50.215/sawfc/WS_SAWFC_Int.asmx" binding="basicHttpBinding" bindingConfiguration="wsSAWFCInterfaceSoap" contract="it.datasphere.ws.wsSAWFCInterfaceSoap" name="wsSAWFCInterfaceSoap" /> </client> I cannot reach the new web service from dev environment, so I cannot modify the Service reference there. Any idea? Thanks a lot!

    Read the article

  • Issues with dynamically loading modules in code with Silverlight/Prism

    - by Greg Bailey
    In my Bootstrapper.cs in GetModuleCatalog, I need to specify the Module types using the typeof(ModuleType). In the example below I'm trying to load the Contact module on demand, but in order to get it into my module catalog, I need to have a reference to it in the project that holds my Bootstrapper. When I add a reference to Contact, then the Contact.dll gets added to the initial xap file, which defeats the purpose of loading the module dynamically. Am I missing something? Do you have to load the module catalog from a file to make this work? var catalog = new ModuleCatalog(); catalog.AddModule(typeof(Core)); catalog.AddModule(typeof(Contact), InitializationMode.OnDemand);

    Read the article

  • Get foreign key in external content type to show up in list view

    - by Rob
    I have come across blogs about how to setup an external content type (e.g. http://www.dotnetmafia.com/blogs/dotnettipoftheday/archive/2010/02/02/it-s-easy-to-configure-an-external-list-with-business-connectivity-services-bcs-in-sharepoint-foundation-2010.aspx) but I have not seen any examples of what to do when your external SQL DB has foreign keys. For example. I have a database that has orders and customers. An order has one and only one customer and a customer can have many orders. How can I setup external content types in such a way that when in the list view of these external content types, I can jump between and possible lookup values to that other type?

    Read the article

  • Drupal Background Image as Block or Node

    - by Marcy Sutton
    Hi There. I am having trouble wrapping my head around how to make editable background images in my custom Drupal 6 theme. My client wants to have a different background image for each main section (which use multiple content types: page, blog, image gallery)... I am wondering, is there a way to make a custom content type into a dynamic background image block? I am using the Image, Image Cache, Views, CCK, Image Assist, Panels, Filefield, and Imagefield modules. What I'd like to do is add a background image field to various content types that allows a user to reference an image from the content library or upload a new image (similar to ImageAssist), and have it apply to a region in my template. Any suggestions on the best approach for this? Thank you!

    Read the article

  • Validate xsl fo in xslt styleesheet

    - by Biegal
    Hi, i have a little problem with validating xml, xslt in details. I have a xslt stylesheet that, transforms xml data source to xsl:fo document. Something like this: <?xml version="1.0" encoding="utf-8"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <xsl:template match="/"> <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format" xmlns="http://www.w3.org/1999/xhtml"> <fo:layout-master-set> <fo:simple-page-master margin-top="25mm" margin-bottom="25mm" margin-left="25mm" margin-right="25mm" page-width="210mm" page-height="297mm" master-name="simplePageLayout"> <fo:region-body region-name="xsl-region-body" column-gap="0.25in" /> <fo:region-before region-name="xsl-region-before" display-align="after" extent="0.1mm" padding-top="0pt" padding-left="0.4in" padding-right="0.4in" padding-bottom="0pt" /> <fo:region-after region-name="xsl-region-after" display-align="before" extent="0.4in" padding-top="4pt" padding-left="0.4in" padding-right="0.4in" padding-bottom="0pt" /> </fo:simple-page-master> <fo:page-sequence-master master-name="default-sequence"> <fo:repeatable-page-master-reference master-reference="simplePageLayout" /> </fo:page-sequence-master> </fo:layout-master-set> <fo:page-sequence master-reference="default-sequence"> <fo:flow flow-name="xsl-region-body"> <fo:block font-family="Segoe UI" color="#000000" font-size="9pt" /> </fo:flow> </fo:page-sequence> </fo:root> </xsl:template> What I want to do, is to validate written xsl:fo elements, ignoring xsl tags. Is it posible? For now I use dtd validation (I have xsd schema too) for validating Fo, but it give me an error on each xsl tag. Summary. Is it posiible to validate only fo elements against the schema, ignoring xsl tags, and how should I do it? Maybe a code snnippet in C#, or a hint how to modify documents? Thanks in advance!

    Read the article

  • Mixing static and dynamic endpoints in app.yaml file

    - by Greg
    I'm trying to describe endpoints in my App Engine app and am having difficulty for directory structures that mix static and dynamic content. But my yaml rules are conflicting with one another. Before I change my directory structure, does anyone have a recommendation? The goal is to create a directory that contains both documentation (static html files) and implementations. /api - /v1 - getitdone.py - doc.html - index.html What I think I should be doing with my application yaml... - url: /api/v1/getitdone script: api/v1/getitdone.py - url: /api/ static_files: api/index.html upload: api/index.html - url: /api static_dir: api But this causes the dynamic endpoints to fail. I'm assuming the static_dir reference is breaking it. How can I do this without describing every script and static file reference (I have many more than are listed here)?

    Read the article

  • Solved::MessageQueue.BeginReceive() null ref error - c#

    - by ltech
    Have a windows service that listens to a msmq. In the OnStart method is have this protected override void OnStart(string[] args) { try { _queue = new MessageQueue(_qPath);//this part works as i had logging before and afer this call //Add MSMQ Event _queue.ReceiveCompleted += new ReceiveCompletedEventHandler(queue_ReceiveCompleted);//this part works as i had logging before and afer this call _queue.BeginReceive();//This is where it is failing - get a null reference exception } catch(Exception ex) { EventLogger.LogEvent(EventSource, EventLogType, "OnStart" + _lineFeed + ex.InnerException.ToString() + _lineFeed + ex.Message.ToString()); } } where private MessageQueue _queue = null; This works on my machine but when deployed to a windows 2003 server and running as Network service account, it fails Exception recvd: Service cannot be started. System.NullReferenceException: Object reference not set to an instance of an object. at MYService.Service.OnStart(String[] args) at System.ServiceProcess.ServiceBase.ServiceQueuedMainCallback(Object state) Solved: Turned out that the Q that i set up, I had to explicitly add Network Service account to it under security tab

    Read the article

  • Replacing text in NSTextFieldCell inside NSTableView

    - by earl.ct
    Whenever a user would type a number, my app would automatically prepend a currency sign before that number. For example, when the user types "1" in a text field, the text inside it becomes "$1.00". All is good when I use an NSNumberFormatter, an NSTextField, and its delegate method control:didFailToFormatString:errorDescription:. - (BOOL)control:(NSControl *)control didFailToFormatString:(NSString *)string errorDescription:(NSString *)error { if ([[control formatter] isKindOfClass:[NSNumberFormatter class]]) { NSNumberFormatter *formatter = [control formatter]; if ([formatter numberStyle] == NSNumberFormatterCurrencyStyle && ! [string hasPrefix:[formatter currencySymbol]]) { NSDecimalNumber *new = [NSDecimalNumber decimalNumberWithString:string]; if (new == [NSDecimalNumber notANumber]) { new = [NSDecimalNumber zero]; } [control setObjectValue:new]; } } return YES;} Now I would like to have this functionality when a user types a number in a cell inside an NSTableView. I tried using control:didFailToFormatString:errorDescription: but the cell would erase the text instead.

    Read the article

  • Progressing Alfresco workflows through web script

    - by Domchi
    I have an Alfresco document reference; what I'm looking for is a way to access workflow attached to that document and finish it (or progress it to the next transition) through Javascript. Almost every example on the web shows how to start workflow, and from the dashlet I could call task command processor (/alfresco/command/task/end/[/transition]) if I knew the task ID, but how do I do the same thing from server-side web script starting only from the document reference? There must be a way to access workflows from document and manage them programatically.

    Read the article

  • Rtti accessing fields and properties in complex data structures

    - by Coco
    As already discussed in Rtti data manipulation and consistency in Delphi 2010 a consistency between the original data and rtti values can be reached by accessing members by using a pair of TRttiField and an instance pointer. This would be very easy in case of a simple class with only basic member types (like e.g. integers or strings). But what if we have structured field types? Here is an example: TIntArray = array [0..1] of Integer; TPointArray = array [0..1] of Point; TExampleClass = class private FPoint : TPoint; FAnotherClass : TAnotherClass; FIntArray : TIntArray; FPointArray : TPointArray; public property Point : TPoint read FPoint write FPoint; //.... and so on end; For an easy access of Members I want to buil a tree of member-nodes, which provides an interface for getting and setting values, getting attributes, serializing/deserializing values and so on. TMemberNode = class private FMember : TRttiMember; FParent : TMemberNode; FInstance : Pointer; public property Value : TValue read GetValue write SetValue; //uses FInstance end; So the most important thing is getting/setting the values, which is done - as stated before - by using the GetValue and SetValue functions of TRttiField. So what is the Instance for FPoint members? Let's say Parent is the Node for TExample class, where the instance is known and the member is a field, then Instance would be: FInstance := Pointer (Integer (Parent.Instance) + TRttiField (FMember).Offset); But what if I want to know the Instance for a record property? There is no offset in this case. So is there a better solution to get a pointer to the data? For the FAnotherClass member, the Instance would be: FInstance := Parent.Value.AsObject; So far the solution works, and data manipulation can be done by using rtti or the original types, without losing information. But things get harder, when working with arrays. Especially the second array of Points. How can I get the instance for the members of points in this case?

    Read the article

  • iphone calls both if and else at the same time?

    - by David Schiefer
    Hi, I need to determine what file type a file is and then perform a certain action for it. this seems to work fine for some types, however all media types such as videos and sound files get mixed up. I determine the file type by doing this: BOOL matchedMP3 = ([[rowValue pathExtension] isEqualToString:@"mp3"]); if (matchedMP3 == YES) { NSLog(@"Matched MP3"); } I do this for various file types and just define an "else" for all the others. Here's the problem though. The iPhone calls them both. Here's what the log reveals: 2010-05-11 18:51:12.421 Test [5113:207] Matched MP3 2010-05-11 18:51:12.449 Test [5113:207] Matched ELSE I've never seen anything like this before. This is my "matchedMP3" function: BOOL matchedMP3 = ([[rowValue pathExtension] isEqualToString:@"mp3"]); if (matchedMP3 == YES) { NSLog(@"Matched MP3"); NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSFileManager *manager = [NSFileManager defaultManager]; self.directoryContent = [manager directoryContentsAtPath:documentsDirectory]; NSString *errorMessage = [documentsDirectory stringByAppendingString:@"/"]; NSString *urlAddress = [errorMessage stringByAppendingString:rowValue]; MPMoviePlayerController *moviePlayer = [[MPMoviePlayerController alloc] initWithContentURL:[NSURL fileURLWithPath:urlAddress]]; moviePlayer.movieControlMode = MPMovieControlModeDefault; moviePlayer.backgroundColor = [UIColor blackColor]; [moviePlayer play]; } and here's the else statement: else { NSLog(@"Matched ELSE"); [[NSUserDefaults standardUserDefaults] setObject:rowValue forKey:@"rowValue"]; NSString*rowValue = [[NSUserDefaults standardUserDefaults] objectForKey:@"rowValue"]; NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSFileManager *manager = [NSFileManager defaultManager]; self.directoryContent = [manager directoryContentsAtPath:documentsDirectory]; NSString *errorMessage = [documentsDirectory stringByAppendingString:@"/"]; NSString *urlAddress = [errorMessage stringByAppendingString:rowValue]; webViewHeader.prompt = rowValue; [documentViewer setDelegate:self]; NSString *encodedString = [urlAddress stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]; //Create a URL object. NSURL *url = [NSURL URLWithString:encodedString]; //URL Requst Object NSURLRequest *requestObj = [NSURLRequest requestWithURL:url]; //Load the request in the UIWebView. [documentViewer loadRequest:requestObj]; [navigationController pushViewController:webView animated:YES]; } I can't see a reason why it wouldn't work. What happens is that both the webview and the MediaPlayer toggle their own player, so they overlap and play their sound/video a few secs apart from each other. Any help would be appreciated & thank for you taking the time to read through my code.

    Read the article

  • Can't select View Content dropdown when adding view in MVC using Interfaces

    - by fearofawhackplanet
    I have my Model defined externally in two projects - a Core project and an Interface project. I am opening the Add View dialogue from my controller, and selecting Create a strongly typed view. In the drop down list, I can select the concrete types like MyProject.Model.Core.OrderDetails, but the interface types like MyProject.Model.Interface.IOrderDetails aren't there. I can type the interface class in manually and everything works, but then the View content menu that lets you select the Create, Delete, List, etc scaffolding is disabled. Is there some problem with using interfaces in MVC? Or is it something else I'm missing?

    Read the article

  • Global find object references in NHibernate

    - by Miral
    Is it possible to perform a global reversed-find on NHibernate-managed objects? Specifically, I have a persistent class called "Io". There are a huge number of fields across multiple tables which can potentially contain an object of that type. Is there a way (given a specific instance of an Io object), to retrieve a list of objects (of any type) that actually do reference that specific object? (Bonus points if it can identify which specific fields actually contain the reference, but that's not critical.) Since the NHibernate mappings define all the links (and the underlying database has corresponding foreign key links), there ought to be some way to do it.

    Read the article

  • problem with trying to create ssms add-in

    - by Karl
    I'm trying to create an add-in for SSMS 2008 and/or 2008 R2 but I've run into a problem straight away. I can get my add-in to work and on SSMS start-up get it to simply show a message box. However, after downloading various code-samples, when trying to reference Microsoft.SqlServer.Management.UI.VSIntegration.ServiceCache I get a null reference exception: Commands2 commands = (Commands2)ServiceCache.ExtensibilityModel.Commands; I get this problem when using SSMS 2008 or SSMS 2008 R2. I'm working on Visual Studio 2010. It's a bit frustrating because I'm keen to learn more about SSMS add-ins but can't seem to get past the few samples out there. Any advice/tips appreciated. Thanks

    Read the article

  • C# Design Layout/Patterns

    - by wpfwannabe
    I am still fairly new to C# and I am trying to decide the best way to structure a new program. Here is what I want to do and I would like feed back on my idea. Presentation Layer Business Layer (Separate Class Library) Data Layer (Separate Class Library) Model Layer (Separate Class Library) What I am struggling with is if it is ok to have the classes in the Data Layer and Business Layer inherit from the types I define in Model Layer. This way I can extended the types as needed in my Business Layer with any new properties I see fit. I might not use every property from the Model type in my Business Layer class but is that really a big deal? If this isn't clear enough I can try and put together an example.

    Read the article

  • Web Crawling Sites with Javascripts or web forms

    - by Jojo
    Hello everyone, I have a webcrawler application. It successfully crawled most common and simple sites. Now i ran into some types of websites wherein HTML documents are dynamically generated through FORMS or javascripts. I believe they can be crawled and I just don't know how. Now, these websites do not show the actual HTML page. I mean if I browse that page in IE or firefox, the HTML code does not match what's actually in the IE or firefox. These sites contain textboxes, checkboxes, etc... so I believe they are what they call "Web Forms". Actually I am not much familiar with web development so correct me if I'm wrong. My question is, does anyone in similar situation as I am now and have successfully solved these types of "challenges"? Does anyone know of a certain book or article regarding web crawling? Those that pertains to these advanced type of websites? Thanks.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 168 169 170 171 172 173 174 175 176 177 178 179  | Next Page >